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1. TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration

Author: Tran, Quang H., Bowler, Brendan P., Endl, Michael, Cochran, William D., MacQueen, Phillip J., Gandolfi, Davide, Persson, Carina M., Fridlund, Malcolm, Palle, Enric, Nowak, Grzegorz, Deeg, Hans J., Luque, Rafael, Livingston, John H., Kabath, Petr, Skarka, Marek, Subjak, Jan, Howell, Steve B., Albrecht, Simon H., Collins, Karen A., Esposito, Massimiliano, Van Eylen, Vincent, Grziwa, Sascha, Goffo, Elisa, Huang, Chelsea X., Jenkins, Jon M., Karjalainen, Marie, Karjalainen, Raine, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Latham, David W., Levine, Alan M., Osborne, H. L. M., Quinn, Samuel N., Redfield, Seth, Ricker, George R., Seager, S., Serrano, Luisa Maria, Smith, Alexis M. S., Twicken, Joseph D., Winn, Joshua N., Tran, Quang H., Bowler, Brendan P., Endl, Michael, Cochran, William D., MacQueen, Phillip J., Gandolfi, Davide, Persson, Carina M., Fridlund, Malcolm, Palle, Enric, Nowak, Grzegorz, Deeg, Hans J., Luque, Rafael, Livingston, John H., Kabath, Petr, Skarka, Marek, Subjak, Jan, Howell, Steve B., Albrecht, Simon H., Collins, Karen A., Esposito, Massimiliano, Van Eylen, Vincent, Grziwa, Sascha, Goffo, Elisa, Huang, Chelsea X., Jenkins, Jon M., Karjalainen, Marie, Karjalainen, Raine, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Latham, David W., Levine, Alan M., Osborne, H. L. M., Quinn, Samuel N., Redfield, Seth, Ricker, George R., Seager, S., Serrano, Luisa Maria, Smith, Alexis M. S., Twicken, Joseph D., and Winn, Joshua N.
Abstract: We report the discovery of two transiting planets around the bright (V = 9.9 mag) main-sequence F7 star TOI-1670 by the Transiting Exoplanet Survey Satellite. TOI-1670 b is a sub-Neptune (R-b = 2.06(-0.15)(+0.19) R-circle plus) on a 10.9 day orbit, and TOI-1670 c is a warm Jupiter (R-c= 0.987(-0.025)(+0.025) R-Jup) on a 40.7 day orbit. Using radial velocity observations gathered with the Tull Coude Spectrograph on the Harlan J. Smith telescope and HARPS-N on the Telescopio Nazionale Galileo, we find a planet mass of M-c = 0.63(-0.08)(+0.09) M(Jup )for the outer warm Jupiter, implying a mean density of rho(c) = 0.81(-0.11)(+0.13) g cm(-3). The inner sub-Neptune is undetected in our radial velocity data (M-b < 0.13 M-Jup at the 99% confidence level). Multiplanet systems like TOI-1670 hosting an outer warm Jupiter on a nearly circular orbit (l(e) = 0.09(-0.04)(+0.05)) and one or more inner coplanar planets are more consistent with gentle formation mechanisms such as disk migration or in situ formation rather than high-eccentricity migration. Of the 11 known systems with a warm Jupiter and a smaller inner companion, eight (73%) are near a low-order mean-motion resonance, which can be a signature of migration. TOI-1670 joins two other systems (27% of this subsample) with period commensurabilities greater than 3, a common feature of in situ formation or halted inward migration. TOI-1670 and the handful of similar systems support a diversity of formation pathways for warm Jupiters.
Published: 2022

2. A Radial Velocity Study of the Planetary System of pi Mensae: Improved Planet Parameters for pi Mensae c and a Third Planet on a 125 Day Orbit

Author: Hatzes, Artie P., Gandolfi, Davide, Korth, Judith, Rodler, Florian, Sabotta, Silvia, Esposito, Massimiliano, Barragan, Oscar, Van Eylen, Vincent, Livingston, John H., Serrano, Luisa Maria, Luque, Rafael, Smith, Alexis M. S., Redfield, Seth, Persson, Carina M., Paetzold, Martin, Palle, Enric, Nowak, Grzegorz, Osborne, Hannah L. M., Narita, Norio, Mathur, Savita, Lam, Kristine W. F., Kabath, Petr, Johnson, Marshall C., Guenther, Eike W., Grziwa, Sascha, Goffo, Elisa, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Csizmadia, Szilard, Cochran, William D., Gonzalez Cuesta, Lucia, Chaturvedi, Priyanka, Carleo, Ilaria, Cabrera, Juan, Beck, Paul G., Albrecht, Simon, Hatzes, Artie P., Gandolfi, Davide, Korth, Judith, Rodler, Florian, Sabotta, Silvia, Esposito, Massimiliano, Barragan, Oscar, Van Eylen, Vincent, Livingston, John H., Serrano, Luisa Maria, Luque, Rafael, Smith, Alexis M. S., Redfield, Seth, Persson, Carina M., Paetzold, Martin, Palle, Enric, Nowak, Grzegorz, Osborne, Hannah L. M., Narita, Norio, Mathur, Savita, Lam, Kristine W. F., Kabath, Petr, Johnson, Marshall C., Guenther, Eike W., Grziwa, Sascha, Goffo, Elisa, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Csizmadia, Szilard, Cochran, William D., Gonzalez Cuesta, Lucia, Chaturvedi, Priyanka, Carleo, Ilaria, Cabrera, Juan, Beck, Paul G., and Albrecht, Simon
Abstract: pi Men hosts a transiting planet detected by the Transiting Exoplanet Survey Satellite space mission and an outer planet in a 5.7 yr orbit discovered by radial velocity (RV) surveys. We studied this system using new RV measurements taken with the HARPS spectrograph on ESO's 3.6 m telescope, as well as archival data. We constrain the stellar RV semiamplitude due to the transiting planet, pi Men c, as K (c) = 1.21 +/- 0.12 m s(-1), resulting in a planet mass of M (c) = 3.63 +/- 0.38 M (circle plus). A planet radius of R (c) = 2.145 +/- 0.015 R (circle plus) yields a bulk density of rho (c) = 2.03 +/- 0.22 g cm(-3). The precisely determined density of this planet and the brightness of the host star make pi Men c an excellent laboratory for internal structure and atmospheric characterization studies. Our HARPS RV measurements also reveal compelling evidence for a third body, pi Men d, with a minimum mass M (d) sin i (d) = 13.38 +/- 1.35 M (circle plus) orbiting with a period of P (orb,d) = 125 days on an eccentric orbit (e (d) = 0.22). A simple dynamical analysis indicates that the orbit of pi Men d is stable on timescales of at least 20 Myr. Given the mutual inclination between the outer gaseous giant and the inner rocky planet and the presence of a third body at 125 days, pi Men is an important planetary system for dynamical and formation studies.
Published: 2022

3. TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

Author: Subjak, Jan, Sharma, Rishikesh, Carmichael, Theron W., Johnson, Marshall C., Gonzales, Erica J., Matthews, Elisabeth, Boffin, Henri M. J., Brahm, Rafael, Chaturvedi, Priyanka, Chakraborty, Abhijit, Ciardi, David R., Collins, Karen A., Esposito, Massimiliano, Fridlund, Malcolm, Gan, Tianjun, Gandolfi, Davide, Garcia, Rafael A., Guenther, Eike, Hatzes, Artie, Latham, David W., Mathis, Stephane, Mathur, Savita, Persson, Carina M., Relles, Howard M., Schlieder, Joshua E., Barclay, Thomas, Dressing, Courtney D., Crossfield, Ian, Howard, Andrew W., Rodler, Florian, Zhou, George, Quinn, Samuel N., Esquerdo, Gilbert A., Calkins, Michael L., Berlind, Perry, Stassun, Keivan G., Blazek, Martin, Skarka, Marek, Spokova, Magdalena, Zak, Jiri, Albrecht, Simon, Alonso Sobrino, Roi, Beck, Paul, Cabrera, Juan, Carleo, Ilaria, Cochran, William D., Csizmadia, Szilard, Dai, Fei, Deeg, Hans J., de Leon, Jerome P., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Fukui, Akihiko, Georgieva, Iskra, Gonzalez-Cuesta, Lucia, Grziwa, Sascha, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Livingston, John H., Lund, Mikkel N., Luque, Rafael, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, Kabath, Petr, Subjak, Jan, Sharma, Rishikesh, Carmichael, Theron W., Johnson, Marshall C., Gonzales, Erica J., Matthews, Elisabeth, Boffin, Henri M. J., Brahm, Rafael, Chaturvedi, Priyanka, Chakraborty, Abhijit, Ciardi, David R., Collins, Karen A., Esposito, Massimiliano, Fridlund, Malcolm, Gan, Tianjun, Gandolfi, Davide, Garcia, Rafael A., Guenther, Eike, Hatzes, Artie, Latham, David W., Mathis, Stephane, Mathur, Savita, Persson, Carina M., Relles, Howard M., Schlieder, Joshua E., Barclay, Thomas, Dressing, Courtney D., Crossfield, Ian, Howard, Andrew W., Rodler, Florian, Zhou, George, Quinn, Samuel N., Esquerdo, Gilbert A., Calkins, Michael L., Berlind, Perry, Stassun, Keivan G., Blazek, Martin, Skarka, Marek, Spokova, Magdalena, Zak, Jiri, Albrecht, Simon, Alonso Sobrino, Roi, Beck, Paul, Cabrera, Juan, Carleo, Ilaria, Cochran, William D., Csizmadia, Szilard, Dai, Fei, Deeg, Hans J., de Leon, Jerome P., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Fukui, Akihiko, Georgieva, Iskra, Gonzalez-Cuesta, Lucia, Grziwa, Sascha, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Livingston, John H., Lund, Mikkel N., Luque, Rafael, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, and Kabath, Petr
Abstract: We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P.=.3.6772.+/-.0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius ( = R 1.34+ R b 0.150.26 J). We obtained highresolution spectroscopic observations with the FIES, Ondr.ejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be Mb.=.53.7.+/-.1.2 MJ. The host star has a mass of Ma.=.1.80.+/-.0.06Me, a radius of Ra.=.1.70.+/-.0.05Re, an effective temperature of Teff.=.7650.+/-.160 K, and a relatively high metallicity of 0.61.+/-.0.07 dex. We used stellar isochrones to derive the age of the system to be 180 Myr, which places its age between that of RIK 72b (a 10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a 600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting mainsequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert (35-55MJ sin i) is reforesting.
Published: 2020

4. It Takes Two Planets in Resonance to Tango around K2-146

Author: Lam, Kristine W. F., Korth, Judith, Masuda, Kento, Csizmadia, Szilard, Eigmueller, Philipp, Kari Stefansson, Gumundur, Endl, Michael, Albrecht, Simon, Robertson, Paul, Luque, Rafael, Livingston, John H., Hirano, Teruyuki, Alonso Sobrino, Roi, Barragan, Oscar, Cabrera, Juan, Carleo, Ilaria, Chaushev, Alexander, Cochran, William D., Dai, Fei, de Leon, Jerome, Deeg, Hans J., Erikson, Anders, Esposito, Massimiliano, Fridlund, Malcolm, Fukui, Akihiko, Gandolfi, Davide, Georgieva, Iskra, Gonzalez Cuesta, Luca, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Lund, Mikkel N., Mahadevan, Suvrath, Mathur, Savita, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Subjak, Jan, Van Eylen, Vincent, Lam, Kristine W. F., Korth, Judith, Masuda, Kento, Csizmadia, Szilard, Eigmueller, Philipp, Kari Stefansson, Gumundur, Endl, Michael, Albrecht, Simon, Robertson, Paul, Luque, Rafael, Livingston, John H., Hirano, Teruyuki, Alonso Sobrino, Roi, Barragan, Oscar, Cabrera, Juan, Carleo, Ilaria, Chaushev, Alexander, Cochran, William D., Dai, Fei, de Leon, Jerome, Deeg, Hans J., Erikson, Anders, Esposito, Massimiliano, Fridlund, Malcolm, Fukui, Akihiko, Gandolfi, Davide, Georgieva, Iskra, Gonzalez Cuesta, Luca, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Lund, Mikkel N., Mahadevan, Suvrath, Mathur, Savita, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Subjak, Jan, and Van Eylen, Vincent
Abstract: K2-146 is a cool, 0.358M dwarf that was found to host a mini-Neptune with a 2.67 day period. The planet exhibited strong transit timing variations (TTVs) of greater than 30 minutes, indicative of the presence of an additional object in the system. Here we report the discovery of the previously undetected outer planet in the system, K2-146 c, using additional photometric data. K2-146 c was found to have a grazing transit geometry and a 3.97 day period. The outer planet was only significantly detected in the latter K2 campaigns presumably because of precession of its orbital plane. The TTVs of K2-146 b and c were measured using observations spanning a baseline of almost 1200 days. We found strong anti -correlation in the TTVs, suggesting the two planets are gravitationally interacting. Our TTV and transit model analyses revealed that K2-146 b has a radius of 2.25 0.10 Re and a mass of 5.6 0.7 Me, whereas K2-146 c has a radius of 2.591 Re and a mass of 7.1 0.9 Me. The inner and outer planets likely have moderate eccentricities of e = 0.14 0.07 and 0.16 0.07, respectively. Long-term numerical integrations of the two -planet orbital solution show that it can be dynamically stable for at least 2 Myr. We show that the resonance angles of the planet pair are librating, which may be an indication that K2-146 b and c are in a 3:2 mean motion resonance. The orbital architecture of the system points to a possible convergent migration origin.
Published: 2020

5. The Multiplanet System TOI-421*

Author: Carleo, Ilaria, Gandolfi, Davide, Barragan, Oscar, Livingston, John H., Persson, Carina M., Lam, Kristine W. F., Vidotto, Aline, Lund, Michael B., D'Angelo, Carolina Villarreal, Collins, Karen A., Fossati, Luca, Howard, Andrew W., Kubyshkina, Daria, Brahm, Rafael, Oklopcic, Antonija, Molliere, Paul, Redfield, Seth, Serrano, Luisa Maria, Dai, Fei, Fridlund, Malcolm, Borsa, Francesco, Korth, Judith, Esposito, Massimiliano, Diaz, Matias R., Nielsen, Louise Dyregaard, Hellier, Coel, Mathur, Savita, Deeg, Hans J., Hatzes, Artie P., Benatti, Serena, Rodler, Florian, Alarcon, Javier, Spina, Lorenzo, Santos, Angela R. G., Georgieva, Iskra, Garcia, Rafael A., Gonzalez-Cuesta, Lucia, Ricker, George R., Vanderspek, Roland, Latham, David W., Seager, Sara, Winn, Joshua N., Jenkins, Jon M., Albrecht, Simon, Batalha, Natalie M., Beard, Corey, Boyd, Patricia T., Bouchy, Francois, Burt, Jennifer A., Butler, R. Paul, Cabrera, Juan, Chontos, Ashley, Ciardi, David R., Cochran, William D., Collins, Kevin, I, Crane, Jeffrey D., Crossfield, Ian, Csizmadia, Szilard, Dragomir, Diana, Dressing, Courtney, Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Espinoza, Nestor, Fausnaugh, Michael, Feng, Fabo, Flowers, Erin, Fulton, Benjamin, Gonzales, Erica J., Grieves, Nolan, Grziwa, Sascha, Guenther, Eike W., Guerrero, Natalia M., Henning, Thomas, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Huber, Daniel, Isaacson, Howard, Jones, Matias, Jordan, Andres, Kabath, Petr, Kane, Stephen R., Knudstrup, Emil, Lubin, Jack, Luque, Rafael, Mireles, Ismael, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Petigura, Erik A., Prieto-Arranz, Jorge, Rauer, Heike, Robertson, Paul, Rose, Mark E., Roy, Arpita, Sarkis, Paula, Schlieder, Joshua E., Segransan, Damien, Shectman, Stephen, Skarka, Marek, Smith, Alexis M. S., Smith, Jeffrey C., Stassun, Keivan, Teske, Johanna, Twicken, Joseph D., Van Eylen, Vincent, Wang, Sharon, Weiss, Lauren M., Wyttenbach, Aurelien, Carleo, Ilaria, Gandolfi, Davide, Barragan, Oscar, Livingston, John H., Persson, Carina M., Lam, Kristine W. F., Vidotto, Aline, Lund, Michael B., D'Angelo, Carolina Villarreal, Collins, Karen A., Fossati, Luca, Howard, Andrew W., Kubyshkina, Daria, Brahm, Rafael, Oklopcic, Antonija, Molliere, Paul, Redfield, Seth, Serrano, Luisa Maria, Dai, Fei, Fridlund, Malcolm, Borsa, Francesco, Korth, Judith, Esposito, Massimiliano, Diaz, Matias R., Nielsen, Louise Dyregaard, Hellier, Coel, Mathur, Savita, Deeg, Hans J., Hatzes, Artie P., Benatti, Serena, Rodler, Florian, Alarcon, Javier, Spina, Lorenzo, Santos, Angela R. G., Georgieva, Iskra, Garcia, Rafael A., Gonzalez-Cuesta, Lucia, Ricker, George R., Vanderspek, Roland, Latham, David W., Seager, Sara, Winn, Joshua N., Jenkins, Jon M., Albrecht, Simon, Batalha, Natalie M., Beard, Corey, Boyd, Patricia T., Bouchy, Francois, Burt, Jennifer A., Butler, R. Paul, Cabrera, Juan, Chontos, Ashley, Ciardi, David R., Cochran, William D., Collins, Kevin, I, Crane, Jeffrey D., Crossfield, Ian, Csizmadia, Szilard, Dragomir, Diana, Dressing, Courtney, Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Espinoza, Nestor, Fausnaugh, Michael, Feng, Fabo, Flowers, Erin, Fulton, Benjamin, Gonzales, Erica J., Grieves, Nolan, Grziwa, Sascha, Guenther, Eike W., Guerrero, Natalia M., Henning, Thomas, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Huber, Daniel, Isaacson, Howard, Jones, Matias, Jordan, Andres, Kabath, Petr, Kane, Stephen R., Knudstrup, Emil, Lubin, Jack, Luque, Rafael, Mireles, Ismael, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Petigura, Erik A., Prieto-Arranz, Jorge, Rauer, Heike, Robertson, Paul, Rose, Mark E., Roy, Arpita, Sarkis, Paula, Schlieder, Joshua E., Segransan, Damien, Shectman, Stephen, Skarka, Marek, Smith, Alexis M. S., Smith, Jeffrey C., Stassun, Keivan, Teske, Johanna, Twicken, Joseph D., Van Eylen, Vincent, Wang, Sharon, Weiss, Lauren M., and Wyttenbach, Aurelien
Abstract: We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P-b = 5.19672 +/- 0.00049 days, a mass of M-b = 7.17 +/- 0.66 M-circle plus, and a radius of R-b = R-circle plus, whereas the outer warm Neptune, TOI-421 c, has a period of P-c = 16.06819 +/- 0.00035 days, a mass of M-c = 16.42(-1.04)(+1.06)M(circle plus), a radius of R-c = 5.09(-0.15)(+0.16)R(circle plus), and a density of rho(c) = 0.685(-0.072)(+0.080) cm(-3). With its characteristics, the outer planet (rho(c) = 0.685(-0.0072)(+0.080) cm(-3)) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly alpha transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.
Published: 2020

6. It Takes Two Planets in Resonance to Tango around K2-146

Author: Lam, Kristine W. F., Korth, Judith, Masuda, Kento, Csizmadia, Szilard, Eigmueller, Philipp, Kari Stefansson, Gumundur, Endl, Michael, Albrecht, Simon, Robertson, Paul, Luque, Rafael, Livingston, John H., Hirano, Teruyuki, Alonso Sobrino, Roi, Barragan, Oscar, Cabrera, Juan, Carleo, Ilaria, Chaushev, Alexander, Cochran, William D., Dai, Fei, de Leon, Jerome, Deeg, Hans J., Erikson, Anders, Esposito, Massimiliano, Fridlund, Malcolm, Fukui, Akihiko, Gandolfi, Davide, Georgieva, Iskra, Gonzalez Cuesta, Luca, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Lund, Mikkel N., Mahadevan, Suvrath, Mathur, Savita, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Subjak, Jan, Van Eylen, Vincent, Lam, Kristine W. F., Korth, Judith, Masuda, Kento, Csizmadia, Szilard, Eigmueller, Philipp, Kari Stefansson, Gumundur, Endl, Michael, Albrecht, Simon, Robertson, Paul, Luque, Rafael, Livingston, John H., Hirano, Teruyuki, Alonso Sobrino, Roi, Barragan, Oscar, Cabrera, Juan, Carleo, Ilaria, Chaushev, Alexander, Cochran, William D., Dai, Fei, de Leon, Jerome, Deeg, Hans J., Erikson, Anders, Esposito, Massimiliano, Fridlund, Malcolm, Fukui, Akihiko, Gandolfi, Davide, Georgieva, Iskra, Gonzalez Cuesta, Luca, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Lund, Mikkel N., Mahadevan, Suvrath, Mathur, Savita, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Subjak, Jan, and Van Eylen, Vincent
Abstract: K2-146 is a cool, 0.358M dwarf that was found to host a mini-Neptune with a 2.67 day period. The planet exhibited strong transit timing variations (TTVs) of greater than 30 minutes, indicative of the presence of an additional object in the system. Here we report the discovery of the previously undetected outer planet in the system, K2-146 c, using additional photometric data. K2-146 c was found to have a grazing transit geometry and a 3.97 day period. The outer planet was only significantly detected in the latter K2 campaigns presumably because of precession of its orbital plane. The TTVs of K2-146 b and c were measured using observations spanning a baseline of almost 1200 days. We found strong anti -correlation in the TTVs, suggesting the two planets are gravitationally interacting. Our TTV and transit model analyses revealed that K2-146 b has a radius of 2.25 0.10 Re and a mass of 5.6 0.7 Me, whereas K2-146 c has a radius of 2.591 Re and a mass of 7.1 0.9 Me. The inner and outer planets likely have moderate eccentricities of e = 0.14 0.07 and 0.16 0.07, respectively. Long-term numerical integrations of the two -planet orbital solution show that it can be dynamically stable for at least 2 Myr. We show that the resonance angles of the planet pair are librating, which may be an indication that K2-146 b and c are in a 3:2 mean motion resonance. The orbital architecture of the system points to a possible convergent migration origin.
Published: 2020

7. TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

Author: Subjak, Jan, Sharma, Rishikesh, Carmichael, Theron W., Johnson, Marshall C., Gonzales, Erica J., Matthews, Elisabeth, Boffin, Henri M. J., Brahm, Rafael, Chaturvedi, Priyanka, Chakraborty, Abhijit, Ciardi, David R., Collins, Karen A., Esposito, Massimiliano, Fridlund, Malcolm, Gan, Tianjun, Gandolfi, Davide, Garcia, Rafael A., Guenther, Eike, Hatzes, Artie, Latham, David W., Mathis, Stephane, Mathur, Savita, Persson, Carina M., Relles, Howard M., Schlieder, Joshua E., Barclay, Thomas, Dressing, Courtney D., Crossfield, Ian, Howard, Andrew W., Rodler, Florian, Zhou, George, Quinn, Samuel N., Esquerdo, Gilbert A., Calkins, Michael L., Berlind, Perry, Stassun, Keivan G., Blazek, Martin, Skarka, Marek, Spokova, Magdalena, Zak, Jiri, Albrecht, Simon, Alonso Sobrino, Roi, Beck, Paul, Cabrera, Juan, Carleo, Ilaria, Cochran, William D., Csizmadia, Szilard, Dai, Fei, Deeg, Hans J., de Leon, Jerome P., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Fukui, Akihiko, Georgieva, Iskra, Gonzalez-Cuesta, Lucia, Grziwa, Sascha, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Livingston, John H., Lund, Mikkel N., Luque, Rafael, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, Kabath, Petr, Subjak, Jan, Sharma, Rishikesh, Carmichael, Theron W., Johnson, Marshall C., Gonzales, Erica J., Matthews, Elisabeth, Boffin, Henri M. J., Brahm, Rafael, Chaturvedi, Priyanka, Chakraborty, Abhijit, Ciardi, David R., Collins, Karen A., Esposito, Massimiliano, Fridlund, Malcolm, Gan, Tianjun, Gandolfi, Davide, Garcia, Rafael A., Guenther, Eike, Hatzes, Artie, Latham, David W., Mathis, Stephane, Mathur, Savita, Persson, Carina M., Relles, Howard M., Schlieder, Joshua E., Barclay, Thomas, Dressing, Courtney D., Crossfield, Ian, Howard, Andrew W., Rodler, Florian, Zhou, George, Quinn, Samuel N., Esquerdo, Gilbert A., Calkins, Michael L., Berlind, Perry, Stassun, Keivan G., Blazek, Martin, Skarka, Marek, Spokova, Magdalena, Zak, Jiri, Albrecht, Simon, Alonso Sobrino, Roi, Beck, Paul, Cabrera, Juan, Carleo, Ilaria, Cochran, William D., Csizmadia, Szilard, Dai, Fei, Deeg, Hans J., de Leon, Jerome P., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Fukui, Akihiko, Georgieva, Iskra, Gonzalez-Cuesta, Lucia, Grziwa, Sascha, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Knudstrup, Emil, Korth, Judith, Lam, Kristine W. F., Livingston, John H., Lund, Mikkel N., Luque, Rafael, Montanes Rodriguez, Pilar, Murgas, Felipe, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, and Kabath, Petr
Abstract: We report the discovery of an intermediate-mass transiting brown dwarf (BD), TOI-503b, from the TESS mission. TOI-503b is the first BD discovered by TESS, and it has circular orbit around a metallic-line A-type star with a period of P.=.3.6772.+/-.0.0001 days. The light curve from TESS indicates that TOI-503b transits its host star in a grazing manner, which limits the precision with which we measure the BD's radius ( = R 1.34+ R b 0.150.26 J). We obtained highresolution spectroscopic observations with the FIES, Ondr.ejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be Mb.=.53.7.+/-.1.2 MJ. The host star has a mass of Ma.=.1.80.+/-.0.06Me, a radius of Ra.=.1.70.+/-.0.05Re, an effective temperature of Teff.=.7650.+/-.160 K, and a relatively high metallicity of 0.61.+/-.0.07 dex. We used stellar isochrones to derive the age of the system to be 180 Myr, which places its age between that of RIK 72b (a 10 Myr old BD in the Upper Scorpius stellar association) and AD 3116b (a 600 Myr old BD in the Praesepe cluster). Given the difficulty in measuring the tidal interactions between BDs and their host stars, we cannot precisely say whether this BD formed in situ or has had its orbit circularized by its host star over the relatively short age of the system. Instead, we offer an examination of plausible values for the tidal quality factor for the star and BD. TOI-503b joins a growing number of known short-period, intermediate-mass BDs orbiting mainsequence stars, and is the second such BD known to transit an A star, after HATS-70b. With the growth in the population in this regime, the driest region in the BD desert (35-55MJ sin i) is reforesting.
Published: 2020

8. The Multiplanet System TOI-421*

Author: Carleo, Ilaria, Gandolfi, Davide, Barragan, Oscar, Livingston, John H., Persson, Carina M., Lam, Kristine W. F., Vidotto, Aline, Lund, Michael B., D'Angelo, Carolina Villarreal, Collins, Karen A., Fossati, Luca, Howard, Andrew W., Kubyshkina, Daria, Brahm, Rafael, Oklopcic, Antonija, Molliere, Paul, Redfield, Seth, Serrano, Luisa Maria, Dai, Fei, Fridlund, Malcolm, Borsa, Francesco, Korth, Judith, Esposito, Massimiliano, Diaz, Matias R., Nielsen, Louise Dyregaard, Hellier, Coel, Mathur, Savita, Deeg, Hans J., Hatzes, Artie P., Benatti, Serena, Rodler, Florian, Alarcon, Javier, Spina, Lorenzo, Santos, Angela R. G., Georgieva, Iskra, Garcia, Rafael A., Gonzalez-Cuesta, Lucia, Ricker, George R., Vanderspek, Roland, Latham, David W., Seager, Sara, Winn, Joshua N., Jenkins, Jon M., Albrecht, Simon, Batalha, Natalie M., Beard, Corey, Boyd, Patricia T., Bouchy, Francois, Burt, Jennifer A., Butler, R. Paul, Cabrera, Juan, Chontos, Ashley, Ciardi, David R., Cochran, William D., Collins, Kevin, I, Crane, Jeffrey D., Crossfield, Ian, Csizmadia, Szilard, Dragomir, Diana, Dressing, Courtney, Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Espinoza, Nestor, Fausnaugh, Michael, Feng, Fabo, Flowers, Erin, Fulton, Benjamin, Gonzales, Erica J., Grieves, Nolan, Grziwa, Sascha, Guenther, Eike W., Guerrero, Natalia M., Henning, Thomas, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Huber, Daniel, Isaacson, Howard, Jones, Matias, Jordan, Andres, Kabath, Petr, Kane, Stephen R., Knudstrup, Emil, Lubin, Jack, Luque, Rafael, Mireles, Ismael, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Petigura, Erik A., Prieto-Arranz, Jorge, Rauer, Heike, Robertson, Paul, Rose, Mark E., Roy, Arpita, Sarkis, Paula, Schlieder, Joshua E., Segransan, Damien, Shectman, Stephen, Skarka, Marek, Smith, Alexis M. S., Smith, Jeffrey C., Stassun, Keivan, Teske, Johanna, Twicken, Joseph D., Van Eylen, Vincent, Wang, Sharon, Weiss, Lauren M., Wyttenbach, Aurelien, Carleo, Ilaria, Gandolfi, Davide, Barragan, Oscar, Livingston, John H., Persson, Carina M., Lam, Kristine W. F., Vidotto, Aline, Lund, Michael B., D'Angelo, Carolina Villarreal, Collins, Karen A., Fossati, Luca, Howard, Andrew W., Kubyshkina, Daria, Brahm, Rafael, Oklopcic, Antonija, Molliere, Paul, Redfield, Seth, Serrano, Luisa Maria, Dai, Fei, Fridlund, Malcolm, Borsa, Francesco, Korth, Judith, Esposito, Massimiliano, Diaz, Matias R., Nielsen, Louise Dyregaard, Hellier, Coel, Mathur, Savita, Deeg, Hans J., Hatzes, Artie P., Benatti, Serena, Rodler, Florian, Alarcon, Javier, Spina, Lorenzo, Santos, Angela R. G., Georgieva, Iskra, Garcia, Rafael A., Gonzalez-Cuesta, Lucia, Ricker, George R., Vanderspek, Roland, Latham, David W., Seager, Sara, Winn, Joshua N., Jenkins, Jon M., Albrecht, Simon, Batalha, Natalie M., Beard, Corey, Boyd, Patricia T., Bouchy, Francois, Burt, Jennifer A., Butler, R. Paul, Cabrera, Juan, Chontos, Ashley, Ciardi, David R., Cochran, William D., Collins, Kevin, I, Crane, Jeffrey D., Crossfield, Ian, Csizmadia, Szilard, Dragomir, Diana, Dressing, Courtney, Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Espinoza, Nestor, Fausnaugh, Michael, Feng, Fabo, Flowers, Erin, Fulton, Benjamin, Gonzales, Erica J., Grieves, Nolan, Grziwa, Sascha, Guenther, Eike W., Guerrero, Natalia M., Henning, Thomas, Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Huber, Daniel, Isaacson, Howard, Jones, Matias, Jordan, Andres, Kabath, Petr, Kane, Stephen R., Knudstrup, Emil, Lubin, Jack, Luque, Rafael, Mireles, Ismael, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Petigura, Erik A., Prieto-Arranz, Jorge, Rauer, Heike, Robertson, Paul, Rose, Mark E., Roy, Arpita, Sarkis, Paula, Schlieder, Joshua E., Segransan, Damien, Shectman, Stephen, Skarka, Marek, Smith, Alexis M. S., Smith, Jeffrey C., Stassun, Keivan, Teske, Johanna, Twicken, Joseph D., Van Eylen, Vincent, Wang, Sharon, Weiss, Lauren M., and Wyttenbach, Aurelien
Abstract: We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of P-b = 5.19672 +/- 0.00049 days, a mass of M-b = 7.17 +/- 0.66 M-circle plus, and a radius of R-b = R-circle plus, whereas the outer warm Neptune, TOI-421 c, has a period of P-c = 16.06819 +/- 0.00035 days, a mass of M-c = 16.42(-1.04)(+1.06)M(circle plus), a radius of R-c = 5.09(-0.15)(+0.16)R(circle plus), and a density of rho(c) = 0.685(-0.072)(+0.080) cm(-3). With its characteristics, the outer planet (rho(c) = 0.685(-0.0072)(+0.080) cm(-3)) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly alpha transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.
Published: 2020

9. The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap

Author: Gandolfi, Davide, Fossati, Luca, Livingston, John H., Stassun, Keivan G., Grziwa, Sascha, Barragan, Oscar, Fridlund, Malcolm, Kubyshkina, Daria, Persson, Carina M., Dai, Fei, Lam, Kristine W. F., Albrecht, Simon, Batalha, Natalie, Beck, Paul G., Justesen, Anders Bo, Cabrera, Juan, Cartwright, Scott, Cochran, William D., Csizmadia, Szilard, Davies, Misty D., Deeg, Hans J., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Esposito, Massimiliano, Garcia, Rafael A., Goeke, Robert, Gonzalez-Cuesta, Lucia, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Korth, Judith, Li, Jie, Luque, Rafael, Mathur, Savita, Montanes Rodriguez, Pilar, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Rowden, Pamela, Torres, Guillermo, Van Eylen, Vincent, Vezie, Michael L., Gandolfi, Davide, Fossati, Luca, Livingston, John H., Stassun, Keivan G., Grziwa, Sascha, Barragan, Oscar, Fridlund, Malcolm, Kubyshkina, Daria, Persson, Carina M., Dai, Fei, Lam, Kristine W. F., Albrecht, Simon, Batalha, Natalie, Beck, Paul G., Justesen, Anders Bo, Cabrera, Juan, Cartwright, Scott, Cochran, William D., Csizmadia, Szilard, Davies, Misty D., Deeg, Hans J., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Esposito, Massimiliano, Garcia, Rafael A., Goeke, Robert, Gonzalez-Cuesta, Lucia, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Korth, Judith, Li, Jie, Luque, Rafael, Mathur, Savita, Montanes Rodriguez, Pilar, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Rowden, Pamela, Torres, Guillermo, Van Eylen, Vincent, and Vezie, Michael L.
Abstract: We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V = 9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary nature of the transit signals and derive the masses of the two transiting planets. With an orbital period of 4.8 days, a mass of 7.51(-1.01)(+1.09) M-circle plus and a radius of 1.64 +/- 0.06 R-circle plus, HD 15337 b joins the growing group of short-period super-Earths known to have a rocky terrestrial composition. The sub-Neptune HD 15337 c has an orbital period of 17.2 days, a mass of 8.11(-1.69)(+1.82) M-circle plus, and a radius of 2.39 +/- 0.12 R-circle plus, suggesting that the planet might be surrounded by a thick atmospheric envelope. The two planets have similar masses and lie on opposite sides of the radius gap, and are thus an excellent testbed for planet formation and evolution theories. Assuming that HD 15337 c hosts a hydrogen-dominated envelope, we employ a recently developed planet atmospheric evolution algorithm in a Bayesian framework to estimate the history of the high-energy (extreme ultraviolet and X-ray) emission of the host star. We find that at an age of 150 Myr, the star possessed on average between 3.7 and 127 times the high-energy luminosity of the current Sun.
Published: 2019

10. The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap

Author: Gandolfi, Davide, Fossati, Luca, Livingston, John H., Stassun, Keivan G., Grziwa, Sascha, Barragan, Oscar, Fridlund, Malcolm, Kubyshkina, Daria, Persson, Carina M., Dai, Fei, Lam, Kristine W. F., Albrecht, Simon, Batalha, Natalie, Beck, Paul G., Justesen, Anders Bo, Cabrera, Juan, Cartwright, Scott, Cochran, William D., Csizmadia, Szilard, Davies, Misty D., Deeg, Hans J., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Esposito, Massimiliano, Garcia, Rafael A., Goeke, Robert, Gonzalez-Cuesta, Lucia, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Korth, Judith, Li, Jie, Luque, Rafael, Mathur, Savita, Montanes Rodriguez, Pilar, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Rowden, Pamela, Torres, Guillermo, Van Eylen, Vincent, Vezie, Michael L., Gandolfi, Davide, Fossati, Luca, Livingston, John H., Stassun, Keivan G., Grziwa, Sascha, Barragan, Oscar, Fridlund, Malcolm, Kubyshkina, Daria, Persson, Carina M., Dai, Fei, Lam, Kristine W. F., Albrecht, Simon, Batalha, Natalie, Beck, Paul G., Justesen, Anders Bo, Cabrera, Juan, Cartwright, Scott, Cochran, William D., Csizmadia, Szilard, Davies, Misty D., Deeg, Hans J., Eigmueller, Philipp, Endl, Michael, Erikson, Anders, Esposito, Massimiliano, Garcia, Rafael A., Goeke, Robert, Gonzalez-Cuesta, Lucia, Guenther, Eike W., Hatzes, Artie P., Hidalgo, Diego, Hirano, Teruyuki, Hjorth, Maria, Kabath, Petr, Knudstrup, Emil, Korth, Judith, Li, Jie, Luque, Rafael, Mathur, Savita, Montanes Rodriguez, Pilar, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Redfield, Seth, Ribas, Ignasi, Skarka, Marek, Smith, Alexis M. S., Rowden, Pamela, Torres, Guillermo, Van Eylen, Vincent, and Vezie, Michael L.
Abstract: We report the discovery of a super-Earth and a sub-Neptune transiting the star HD 15337 (TOI-402, TIC 120896927), a bright (V = 9) K1 dwarf observed by the Transiting Exoplanet Survey Satellite (TESS) in Sectors 3 and 4. We combine the TESS photometry with archival High Accuracy Radial velocity Planet Searcher spectra to confirm the planetary nature of the transit signals and derive the masses of the two transiting planets. With an orbital period of 4.8 days, a mass of 7.51(-1.01)(+1.09) M-circle plus and a radius of 1.64 +/- 0.06 R-circle plus, HD 15337 b joins the growing group of short-period super-Earths known to have a rocky terrestrial composition. The sub-Neptune HD 15337 c has an orbital period of 17.2 days, a mass of 8.11(-1.69)(+1.82) M-circle plus, and a radius of 2.39 +/- 0.12 R-circle plus, suggesting that the planet might be surrounded by a thick atmospheric envelope. The two planets have similar masses and lie on opposite sides of the radius gap, and are thus an excellent testbed for planet formation and evolution theories. Assuming that HD 15337 c hosts a hydrogen-dominated envelope, we employ a recently developed planet atmospheric evolution algorithm in a Bayesian framework to estimate the history of the high-energy (extreme ultraviolet and X-ray) emission of the host star. We find that at an age of 150 Myr, the star possessed on average between 3.7 and 127 times the high-energy luminosity of the current Sun.
Published: 2019

11. K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths

Author: Hirano, Teruyuki, Dai, Fei, Livingston, John H., Fujii, Yuka, Cochran, William D., Endl, Michael, Gandolfi, Davide, Redfield, Seth, Winn, Joshua N., Guenther, Eike W., Prieto-Arranz, Jorge, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Cauley, P. Wilson, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Fukui, Akihiko, Grziwa, Sascha, Hatzes, Artie P., Korth, Judith, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Rauer, Heike, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, Hirano, Teruyuki, Dai, Fei, Livingston, John H., Fujii, Yuka, Cochran, William D., Endl, Michael, Gandolfi, Davide, Redfield, Seth, Winn, Joshua N., Guenther, Eike W., Prieto-Arranz, Jorge, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Cauley, P. Wilson, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Fukui, Akihiko, Grziwa, Sascha, Hatzes, Artie P., Korth, Judith, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Rauer, Heike, Ribas, Ignasi, Smith, Alexis M. S., and Van Eylen, Vincent
Abstract: We report on the discovery of three transiting super-Earths around K2-155 (EPIC 210897587), a relatively bright early M dwarf (V = 12.81 mag) observed during Campaign 13 of the NASA K2 mission. To characterize the system and validate the planet candidates, we conducted speckle imaging and high-dispersion optical spectroscopy, including radial velocity measurements. Based on the K2 light curve and the spectroscopic characterization of the host star, the planet sizes and orbital periods are 1.55(-0.17)(+0.20) R-circle plus and 6.34365 +/- 0.00028 days for the inner planet; 1.95(-0.22)(+0.27) R-circle plus and 13.85402 +/- 0.00088 days for the middle planet; and 1.64(-0.17)(+0.18) R-circle plus and 40.6835 +/- 0.0031 days for the outer planet. The outer planet (K2-155d) is near the habitable zone, with an insolation 1.67 +/- 0.38 times that of the Earth. The planet's radius falls within the range between that of smaller rocky planets and larger gas-rich planets. To assess the habitability of this planet, we present a series of three-dimensional global climate simulations, assuming that K2-155d is tidally locked and has an Earth-like composition and atmosphere. We find that the planet can maintain a moderate surface temperature if the insolation proves to be smaller than similar to 1.5 times that of the Earth. Doppler mass measurements, transit spectroscopy, and other follow-up observations should be rewarding, as K2-155 is one of the optically brightest M dwarfs known to harbor transiting planets.
Published: 2018

12. Exoplanets around Low-mass Stars Unveiled by K2

Author: Hirano, Teruyuki, Dai, Fei, Gandolfi, Davide, Fukui, Akihiko, Livingston, John H., Miyakawa, Kohei, Endl, Michael, Cochran, William D., Alonso-Floriano, Francisco J., Kuzuhara, Masayuki, Montes, David, Ryu, Tsuguru, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Korth, Judith, Kudo, Tomoyuki, Kusakabe, Nobuhiko, Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Ribas, Ignasi, Sato, Bun'ei, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Winn, Joshua N., Hirano, Teruyuki, Dai, Fei, Gandolfi, Davide, Fukui, Akihiko, Livingston, John H., Miyakawa, Kohei, Endl, Michael, Cochran, William D., Alonso-Floriano, Francisco J., Kuzuhara, Masayuki, Montes, David, Ryu, Tsuguru, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Korth, Judith, Kudo, Tomoyuki, Kusakabe, Nobuhiko, Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Ribas, Ignasi, Sato, Bun'ei, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, and Winn, Joshua N.
Abstract: We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R-p on stellar insolation and metallicity [Fe/H]. We confirm that for periods P less than or similar to 2 days, planets with a radius R-p greater than or similar to 2 R-circle plus are less common than planets with a radius between 1-2 R-circle plus. We also see a hint of the radius valley between 1.5 and 2 R-circle plus, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R-circle plus are found around the most metal-rich M dwarfs.
Published: 2018

13. Three Small Planets Transiting a Hyades Star

Author: Livingston, John H., Dai, Fei, Hirano, Teruyuki, Gandolfi, Davide, Nowak, Grzegorz, Endl, Michael, Velasco, Sergio, Fukui, Akihiko, Narita, Norio, Prieto-Arranz, Jorge, Barragan, Oscar, Cusano, Felice, Albrecht, Simon, Cabrera, Juan, Cochran, William D., Csizmadia, Szilard, Deeg, Hans J., Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Kawauchi, Kiyoe, Korth, Judith, Nespral, David, Palle, Enric, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Watanabe, Noriharu, Winn, Joshua N., Livingston, John H., Dai, Fei, Hirano, Teruyuki, Gandolfi, Davide, Nowak, Grzegorz, Endl, Michael, Velasco, Sergio, Fukui, Akihiko, Narita, Norio, Prieto-Arranz, Jorge, Barragan, Oscar, Cusano, Felice, Albrecht, Simon, Cabrera, Juan, Cochran, William D., Csizmadia, Szilard, Deeg, Hans J., Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Kawauchi, Kiyoe, Korth, Judith, Nespral, David, Palle, Enric, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Watanabe, Noriharu, and Winn, Joshua N.
Abstract: We present the discovery of three small planets transiting K2-136 (LP 358 348, EPIC 247589423), a late K dwarf in the Hyades. The planets have orbital periods of 7.9757 +/- 0.0011, 17.30681(-0.00036)(+0.00034), and 25.5715(-0.0040)(+0.0038) days , and radii of 1.05 +/- 0.16, 3.14 +/- 0.36, and 1.55(-0.21)(+0.24) R-circle plus, respectively. With an age of 600-800 Myr, these planets are some of the smallest and youngest transiting planets known. Due to the relatively bright (J = 9.1) host star, the planets are compelling targets for future characterization via radial velocity mass measurements and transmission spectroscopy. As the first known star with multiple transiting planets in a cluster, the system should be helpful for testing theories of planet formation and migration.
Published: 2018

14. 44 Validated Planets from K2 Campaign 10

Author: Livingston, John H., Endl, Michael, Dai, Fei, Cochran, William D., Barragan, Oscar, Gandolfi, Davide, Hirano, Teruyuki, Grziwa, Sascha, Smith, Alexis M. S., Albrecht, Simon, Cabrera, Juan, Csizmadia, Szilard, de Leon, Jerome P., Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Everett, Mark, Fridlund, Malcolm, Fukui, Akihiko, Guenther, Eike W., Hatzes, Artie P., Howell, Steve, Korth, Judith, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Tamura, Motohide, Van Eylen, Vincent, Winn, Joshua N., Livingston, John H., Endl, Michael, Dai, Fei, Cochran, William D., Barragan, Oscar, Gandolfi, Davide, Hirano, Teruyuki, Grziwa, Sascha, Smith, Alexis M. S., Albrecht, Simon, Cabrera, Juan, Csizmadia, Szilard, de Leon, Jerome P., Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Everett, Mark, Fridlund, Malcolm, Fukui, Akihiko, Guenther, Eike W., Hatzes, Artie P., Howell, Steve, Korth, Judith, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Tamura, Motohide, Van Eylen, Vincent, and Winn, Joshua N.
Abstract: We present 44 validated planets from the 10th observing campaign of the NASA K2 mission, as well as highresolution spectroscopy and speckle imaging follow-up observations. These 44 planets come from an initial set of 72 vetted candidates, which we subjected to a validation process incorporating pixel-level analyses, light curve analyses, observational constraints, and statistical false positive probabilities. Our validated planet sample has median values of R-p = 2.2 R-circle plus, P-orb = 6.9 days, T-eq = 890 K, and J = 11.2 mag. Of particular interest are four ultrashort period planets (P-orb less than or similar to 1 day), 16 planets smaller than 2 R-circle plus, and two planets with large predicted amplitude atmospheric transmission features orbiting infrared-bright stars. We also present 27 planet candidates, most of which are likely to be real and worthy of further observations. Our validated planet sample includes 24 new discoveries and has enhanced the number of currently known super-Earths (R-p approximate to 1-2R(circle plus)), sub-Neptunes (R-p approximate to 2-4R(circle plus)), and subSaturns (R-p approximate to 4-8R(circle plus)) orbiting bright stars (J = 8-10 mag) by similar to 4%, similar to 17%, and similar to 11%, respectively.
Published: 2018

15. K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths

Author: Hirano, Teruyuki, Dai, Fei, Livingston, John H., Fujii, Yuka, Cochran, William D., Endl, Michael, Gandolfi, Davide, Redfield, Seth, Winn, Joshua N., Guenther, Eike W., Prieto-Arranz, Jorge, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Cauley, P. Wilson, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Fukui, Akihiko, Grziwa, Sascha, Hatzes, Artie P., Korth, Judith, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Rauer, Heike, Ribas, Ignasi, Smith, Alexis M. S., Van Eylen, Vincent, Hirano, Teruyuki, Dai, Fei, Livingston, John H., Fujii, Yuka, Cochran, William D., Endl, Michael, Gandolfi, Davide, Redfield, Seth, Winn, Joshua N., Guenther, Eike W., Prieto-Arranz, Jorge, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Cauley, P. Wilson, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Fukui, Akihiko, Grziwa, Sascha, Hatzes, Artie P., Korth, Judith, Narita, Norio, Nespral, David, Niraula, Prajwal, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Rauer, Heike, Ribas, Ignasi, Smith, Alexis M. S., and Van Eylen, Vincent
Abstract: We report on the discovery of three transiting super-Earths around K2-155 (EPIC 210897587), a relatively bright early M dwarf (V = 12.81 mag) observed during Campaign 13 of the NASA K2 mission. To characterize the system and validate the planet candidates, we conducted speckle imaging and high-dispersion optical spectroscopy, including radial velocity measurements. Based on the K2 light curve and the spectroscopic characterization of the host star, the planet sizes and orbital periods are 1.55(-0.17)(+0.20) R-circle plus and 6.34365 +/- 0.00028 days for the inner planet; 1.95(-0.22)(+0.27) R-circle plus and 13.85402 +/- 0.00088 days for the middle planet; and 1.64(-0.17)(+0.18) R-circle plus and 40.6835 +/- 0.0031 days for the outer planet. The outer planet (K2-155d) is near the habitable zone, with an insolation 1.67 +/- 0.38 times that of the Earth. The planet's radius falls within the range between that of smaller rocky planets and larger gas-rich planets. To assess the habitability of this planet, we present a series of three-dimensional global climate simulations, assuming that K2-155d is tidally locked and has an Earth-like composition and atmosphere. We find that the planet can maintain a moderate surface temperature if the insolation proves to be smaller than similar to 1.5 times that of the Earth. Doppler mass measurements, transit spectroscopy, and other follow-up observations should be rewarding, as K2-155 is one of the optically brightest M dwarfs known to harbor transiting planets.
Published: 2018

16. Exoplanets around Low-mass Stars Unveiled by K2

Author: Hirano, Teruyuki, Dai, Fei, Gandolfi, Davide, Fukui, Akihiko, Livingston, John H., Miyakawa, Kohei, Endl, Michael, Cochran, William D., Alonso-Floriano, Francisco J., Kuzuhara, Masayuki, Montes, David, Ryu, Tsuguru, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Korth, Judith, Kudo, Tomoyuki, Kusakabe, Nobuhiko, Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Ribas, Ignasi, Sato, Bun'ei, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Winn, Joshua N., Hirano, Teruyuki, Dai, Fei, Gandolfi, Davide, Fukui, Akihiko, Livingston, John H., Miyakawa, Kohei, Endl, Michael, Cochran, William D., Alonso-Floriano, Francisco J., Kuzuhara, Masayuki, Montes, David, Ryu, Tsuguru, Albrecht, Simon, Barragan, Oscar, Cabrera, Juan, Csizmadia, Szilard, Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Korth, Judith, Kudo, Tomoyuki, Kusakabe, Nobuhiko, Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Ribas, Ignasi, Sato, Bun'ei, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, and Winn, Joshua N.
Abstract: We present the detection and follow-up observations of planetary candidates around low-mass stars observed by the K2 mission. Based on light-curve analysis, adaptive-optics imaging, and optical spectroscopy at low and high resolution (including radial velocity measurements), we validate 16 planets around 12 low-mass stars observed during K2 campaigns 5-10. Among the 16 planets, 12 are newly validated, with orbital periods ranging from 0.96 to 33 days. For one of the planets (K2-151b), we present ground-based transit photometry, allowing us to refine the ephemerides. Combining our K2 M-dwarf planets together with the validated or confirmed planets found previously, we investigate the dependence of planet radius R-p on stellar insolation and metallicity [Fe/H]. We confirm that for periods P less than or similar to 2 days, planets with a radius R-p greater than or similar to 2 R-circle plus are less common than planets with a radius between 1-2 R-circle plus. We also see a hint of the radius valley between 1.5 and 2 R-circle plus, which has been seen for close-in planets around FGK stars. These features in the radius/period distribution could be attributed to photoevaporation of planetary envelopes by high-energy photons from the host star, as they have for FGK stars. For the M dwarfs, though, the features are not as well defined, and we cannot rule out other explanations such as atmospheric loss from internal planetary heat sources or truncation of the protoplanetary disk. There also appears to be a relation between planet size and metallicity: the few planets larger than about 3 R-circle plus are found around the most metal-rich M dwarfs.
Published: 2018

17. Three Small Planets Transiting a Hyades Star

Author: Livingston, John H., Dai, Fei, Hirano, Teruyuki, Gandolfi, Davide, Nowak, Grzegorz, Endl, Michael, Velasco, Sergio, Fukui, Akihiko, Narita, Norio, Prieto-Arranz, Jorge, Barragan, Oscar, Cusano, Felice, Albrecht, Simon, Cabrera, Juan, Cochran, William D., Csizmadia, Szilard, Deeg, Hans J., Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Kawauchi, Kiyoe, Korth, Judith, Nespral, David, Palle, Enric, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Watanabe, Noriharu, Winn, Joshua N., Livingston, John H., Dai, Fei, Hirano, Teruyuki, Gandolfi, Davide, Nowak, Grzegorz, Endl, Michael, Velasco, Sergio, Fukui, Akihiko, Narita, Norio, Prieto-Arranz, Jorge, Barragan, Oscar, Cusano, Felice, Albrecht, Simon, Cabrera, Juan, Cochran, William D., Csizmadia, Szilard, Deeg, Hans J., Eigmueller, Philipp, Erikson, Anders, Fridlund, Malcolm, Grziwa, Sascha, Guenther, Eike W., Hatzes, Artie P., Kawauchi, Kiyoe, Korth, Judith, Nespral, David, Palle, Enric, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Smith, Alexis M. S., Tamura, Motohide, Tanaka, Yusuke, Van Eylen, Vincent, Watanabe, Noriharu, and Winn, Joshua N.
Abstract: We present the discovery of three small planets transiting K2-136 (LP 358 348, EPIC 247589423), a late K dwarf in the Hyades. The planets have orbital periods of 7.9757 +/- 0.0011, 17.30681(-0.00036)(+0.00034), and 25.5715(-0.0040)(+0.0038) days , and radii of 1.05 +/- 0.16, 3.14 +/- 0.36, and 1.55(-0.21)(+0.24) R-circle plus, respectively. With an age of 600-800 Myr, these planets are some of the smallest and youngest transiting planets known. Due to the relatively bright (J = 9.1) host star, the planets are compelling targets for future characterization via radial velocity mass measurements and transmission spectroscopy. As the first known star with multiple transiting planets in a cluster, the system should be helpful for testing theories of planet formation and migration.
Published: 2018

18. 44 Validated Planets from K2 Campaign 10

Author: Livingston, John H., Endl, Michael, Dai, Fei, Cochran, William D., Barragan, Oscar, Gandolfi, Davide, Hirano, Teruyuki, Grziwa, Sascha, Smith, Alexis M. S., Albrecht, Simon, Cabrera, Juan, Csizmadia, Szilard, de Leon, Jerome P., Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Everett, Mark, Fridlund, Malcolm, Fukui, Akihiko, Guenther, Eike W., Hatzes, Artie P., Howell, Steve, Korth, Judith, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Tamura, Motohide, Van Eylen, Vincent, Winn, Joshua N., Livingston, John H., Endl, Michael, Dai, Fei, Cochran, William D., Barragan, Oscar, Gandolfi, Davide, Hirano, Teruyuki, Grziwa, Sascha, Smith, Alexis M. S., Albrecht, Simon, Cabrera, Juan, Csizmadia, Szilard, de Leon, Jerome P., Deeg, Hans, Eigmueller, Philipp, Erikson, Anders, Everett, Mark, Fridlund, Malcolm, Fukui, Akihiko, Guenther, Eike W., Hatzes, Artie P., Howell, Steve, Korth, Judith, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Persson, Carina M., Prieto-Arranz, Jorge, Rauer, Heike, Tamura, Motohide, Van Eylen, Vincent, and Winn, Joshua N.
Abstract: We present 44 validated planets from the 10th observing campaign of the NASA K2 mission, as well as highresolution spectroscopy and speckle imaging follow-up observations. These 44 planets come from an initial set of 72 vetted candidates, which we subjected to a validation process incorporating pixel-level analyses, light curve analyses, observational constraints, and statistical false positive probabilities. Our validated planet sample has median values of R-p = 2.2 R-circle plus, P-orb = 6.9 days, T-eq = 890 K, and J = 11.2 mag. Of particular interest are four ultrashort period planets (P-orb less than or similar to 1 day), 16 planets smaller than 2 R-circle plus, and two planets with large predicted amplitude atmospheric transmission features orbiting infrared-bright stars. We also present 27 planet candidates, most of which are likely to be real and worthy of further observations. Our validated planet sample includes 24 new discoveries and has enhanced the number of currently known super-Earths (R-p approximate to 1-2R(circle plus)), sub-Neptunes (R-p approximate to 2-4R(circle plus)), and subSaturns (R-p approximate to 4-8R(circle plus)) orbiting bright stars (J = 8-10 mag) by similar to 4%, similar to 17%, and similar to 11%, respectively.
Published: 2018

19. EPIC 219388192b-An Inhabitant of the Brown Dwarf Desert in the Ruprecht 147 Open Cluster

Author: Nowak, Grzegorz, Palle, Enric, Gandolfi, Davide, Dai, Fei, Lanza, Antonino F., Hirano, Teruyuki, Barragan, Oscar, Fukui, Akihiko, Bruntt, Hans, Endl, Michael, Cochran, William D., Moroni, Pier G. Prada, Prieto-Arranz, Jorge, Kiilerich, Amanda, Nespral, David, Hatzes, Artie P., Albrecht, Simon, Deeg, Hans, Winn, Joshua N., Yu, Liang, Kuzuhara, Masayuki, Grziwa, Sascha, Smith, Alexis M. S., Guenther, Eike W., Van Eylen, Vincent, Csizmadia, Szilard, Fridlund, Malcolm, Cabrera, Juan, Eigmueller, Philipp, Erikson, Anders, Korth, Judith, Narita, Norio, Paetzold, Martin, Rauer, Heike, Ribas, Ignasi, Nowak, Grzegorz, Palle, Enric, Gandolfi, Davide, Dai, Fei, Lanza, Antonino F., Hirano, Teruyuki, Barragan, Oscar, Fukui, Akihiko, Bruntt, Hans, Endl, Michael, Cochran, William D., Moroni, Pier G. Prada, Prieto-Arranz, Jorge, Kiilerich, Amanda, Nespral, David, Hatzes, Artie P., Albrecht, Simon, Deeg, Hans, Winn, Joshua N., Yu, Liang, Kuzuhara, Masayuki, Grziwa, Sascha, Smith, Alexis M. S., Guenther, Eike W., Van Eylen, Vincent, Csizmadia, Szilard, Fridlund, Malcolm, Cabrera, Juan, Eigmueller, Philipp, Erikson, Anders, Korth, Judith, Narita, Norio, Paetzold, Martin, Rauer, Heike, and Ribas, Ignasi
Abstract: We report the discovery of EPIC 219388192b, a transiting brown dwarf in a 5.3 day orbit around a member star of Ruprecht 147, the oldest nearby open cluster association, which was photometrically monitored by K2 during its Campaign 7. We combine the K2 time-series data with ground-based adaptive optics imaging and high-resolution spectroscopy to rule out false positive scenarios and determine the main parameters of the system. EPIC 219388192b has a radius of R-b= 0.937 +/- 0.032 R-Jup and mass of M-b= 36.84 +/- 0.97 M-Jup, yielding a mean density of 59.6 +/- 7.6 g cm(- 3). The host star is nearly a solar twin with mass M-star = 1.01 +/- 0.04 Me, radius R-star = 1.01 +/- 0.03 R-circle dot, effective temperature T-eff = 5850 +/- 85 K, and iron abundance [Fe/ H]. = 0.03 +/- 0.08 dex. Its age, spectroscopic distance, and reddening are consistent with those of Ruprecht 147, corroborating its cluster membership. EPIC 219388192b is the first mature brown dwarf with precise determinations of mass, radius, and age, and serves as benchmark for evolutionary models in the substellar regime.
Published: 2017

20. K2-60b and K2-107b. A Sub-Jovian and a Jovian Planet from the K2 Mission

Author: Eigmueller, Philipp, Gandolfi, Davide, Persson, Carina M., Donati, Paolo, Fridlund, Malcolm, Csizmadia, Szilard, Barragan, Oscar, Smith, Alexis M. S., Cabrera, Juan, Korth, Judith, Grziwa, Sascha, Prieto-Arranz, Jorge, Nespral, David, Saario, Joonas, Cochran, William D., Cusano, Felice, Deeg, Hans J., Endl, Michael, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Paetzold, Martin, Rauer, Heike, Eigmueller, Philipp, Gandolfi, Davide, Persson, Carina M., Donati, Paolo, Fridlund, Malcolm, Csizmadia, Szilard, Barragan, Oscar, Smith, Alexis M. S., Cabrera, Juan, Korth, Judith, Grziwa, Sascha, Prieto-Arranz, Jorge, Nespral, David, Saario, Joonas, Cochran, William D., Cusano, Felice, Deeg, Hans J., Endl, Michael, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Paetzold, Martin, and Rauer, Heike
Abstract: We report the characterization and independent detection of K2-60b, as well as the detection and characterization of K2-107b, two transiting hot gaseous planets from the K2 space mission. We confirm the planetary nature of the two systems and determine their fundamental parameters combining the K2 time-series data with FIES @ NOT and HARPS-N @ TNG spectroscopic observations. K2-60b has a radius of 0.683 +/- 0.037 R-Jup and a mass of 0.426 +/- 0.037 M-Jup and orbits a G4 V star with an orbital period of 3.00267 +/- 0.00006 days. K2-107b has a radius of 1.44 +/- 0.15 R-Jup and a mass of 0.84 +/- 0.08 M-Jup and orbits an F9 IV star every 3.31392 +/- 0.00002 days. K2-60b is among the few planets at the edge of the so-called desert of short-period sub-Jovian planets. K2107b is a highly inflated Jovian planet orbiting an evolved star about to leave the main sequence.
Published: 2017

21. The Transiting Multi-planet System HD3167: A 5.7M(circle plus) Super-Earth and an 8.3M(circle plus) Mini-Neptune

Author: Gandolfi, Davide, Barragan, Oscar, Hatzes, Artie P., Fridlund, Malcolm, Fossati, Luca, Donati, Paolo, Johnson, Marshall C., Nowak, Grzegorz, Prieto-Arranz, Jorge, Albrecht, Simon, Dai, Fei, Deeg, Hans, Endl, Michael, Grziwa, Sascha, Hjorth, Maria, Korth, Judith, Nespral, David, Saario, Joonas, Smith, Alexis M. S., Antoniciello, Giuliano, Alarcon, Javier, Bedell, Megan, Blay, Pere, Brems, Stefan S., Cabrera, Juan, Csizmadia, Szilard, Cusano, Felice, Cochran, William D., Eigmller, Philipp, Erikson, Anders, Gonzalez Hernandez, Jonay I., Guenther, Eike W., Hirano, Teruyuki, Suarez Mascareno, Alejandro, Narita, Norio, Palle, Enric, Parviainen, Hannu, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Saviane, Ivo, Schmidtobreick, Linda, Van Eylen, Vincent, Winn, Joshua N., Zakhozhay, Olga V., Gandolfi, Davide, Barragan, Oscar, Hatzes, Artie P., Fridlund, Malcolm, Fossati, Luca, Donati, Paolo, Johnson, Marshall C., Nowak, Grzegorz, Prieto-Arranz, Jorge, Albrecht, Simon, Dai, Fei, Deeg, Hans, Endl, Michael, Grziwa, Sascha, Hjorth, Maria, Korth, Judith, Nespral, David, Saario, Joonas, Smith, Alexis M. S., Antoniciello, Giuliano, Alarcon, Javier, Bedell, Megan, Blay, Pere, Brems, Stefan S., Cabrera, Juan, Csizmadia, Szilard, Cusano, Felice, Cochran, William D., Eigmller, Philipp, Erikson, Anders, Gonzalez Hernandez, Jonay I., Guenther, Eike W., Hirano, Teruyuki, Suarez Mascareno, Alejandro, Narita, Norio, Palle, Enric, Parviainen, Hannu, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Saviane, Ivo, Schmidtobreick, Linda, Van Eylen, Vincent, Winn, Joshua N., and Zakhozhay, Olga V.
Abstract: HD3167 is a bright (V = 8.9 mag) K0V star observed by the NASA's K2 space mission during its Campaign 8. It has been recently found to host two small transiting planets, namely, HD 3167b, an ultra short period (0.96 days) super-Earth, and HD 3167c, a mini-Neptune on a relatively long-period orbit (29.85 d). Here we present an intensive radial velocity follow-up of HD 3167 performed with the FIES@NOT, HARPS@ESO-3.6m, and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69 +/- -0.44 M-circle plus, radius of 1.574 +/- -0.054 R-circle plus, and mean density of 8.00(-0.98)(+1.0) g/cm(-3), HD 3167b joins the small group of ultra-short period planets known to have a rocky terrestrial composition. HD 3167c has a mass of 8.33(-1.85)(+1.79) M-circle plus and a radius of 2.740(-0.100)(+0.106) R-circle plus, yielding a mean density of 2.21(-0.53)(+0.56) g/cm(-3), indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (similar to 350 km) and the brightness of the host star make HD 3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the radial velocity measurements but the currently available data set does not allow us to draw any firm conclusion on the origin of the observed variation.
Published: 2017

22. The Discovery and Mass Measurement of a New Ultra-short-period Planet: EPIC 228732031b

Author: Dai, Fei, Winn, Joshua N., Gandolfi, Davide, Wang, Sharon X., Teske, Johanna K., Burt, Jennifer, Albrecht, Simon, Barragan, Oscar, Cochran, William D., Endl, Michael, Fridlund, Malcolm, Hatzes, Artie P., Hirano, Teruyuki, Hirsch, Lea A., Johnson, Marshall C., Justesen, Anders Bo, Livingston, John, Persson, Carina M., Prieto-Arranz, Jorge, Vanderburg, Andrew, Alonso, Roi, Antoniciello, Giuliano, Arriagada, Pamela, Butler, R. P., Cabrera, Juan, Crane, Jeffrey D., Cusano, Felice, Csizmadia, Szilard, Deeg, Hans, Dieterich, Sergio B., Eigmueller, Philipp, Erikson, Anders, Everett, Mark E., Fukui, Akihiko, Grziwa, Sascha, Guenther, Eike W., Henry, Gregory W., Howell, Steve B., Johnson, John Asher, Korth, Judith, Kuzuhara, Masayuki, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Rauer, Heike, Montanes Rodriguez, Pilar, Shectman, Stephen A., Smith, Alexis M. S., Thompson, Ian B., Van Eylen, Vincent, Williamson, Michael W., Wittenmyer, Robert A., Dai, Fei, Winn, Joshua N., Gandolfi, Davide, Wang, Sharon X., Teske, Johanna K., Burt, Jennifer, Albrecht, Simon, Barragan, Oscar, Cochran, William D., Endl, Michael, Fridlund, Malcolm, Hatzes, Artie P., Hirano, Teruyuki, Hirsch, Lea A., Johnson, Marshall C., Justesen, Anders Bo, Livingston, John, Persson, Carina M., Prieto-Arranz, Jorge, Vanderburg, Andrew, Alonso, Roi, Antoniciello, Giuliano, Arriagada, Pamela, Butler, R. P., Cabrera, Juan, Crane, Jeffrey D., Cusano, Felice, Csizmadia, Szilard, Deeg, Hans, Dieterich, Sergio B., Eigmueller, Philipp, Erikson, Anders, Everett, Mark E., Fukui, Akihiko, Grziwa, Sascha, Guenther, Eike W., Henry, Gregory W., Howell, Steve B., Johnson, John Asher, Korth, Judith, Kuzuhara, Masayuki, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Rauer, Heike, Montanes Rodriguez, Pilar, Shectman, Stephen A., Smith, Alexis M. S., Thompson, Ian B., Van Eylen, Vincent, Williamson, Michael W., and Wittenmyer, Robert A.
Abstract: We report the discovery of a new ultra-short-period planet and summarize the properties of all such planets for which the mass and radius have been measured. The new planet, EPIC. 228732031b, was discovered in K2 Campaign 10. It has a radius of 1.81(-0.12)(+0.16) R-circle plus and orbits a G dwarf with a period of 8.9 hr. Radial velocities obtained with Magellan/PFS and TNG/HARPS-N show evidence for stellar activity along with orbital motion. We determined the planetary mass using two different methods: (1) the floating chunk offset method, based only on changes in velocity observed on the same night; and (2) a Gaussian process regression based on both the radial velocity and photometric time series. The results are consistent and lead to a mass measurement of 6.5. +/- 1.6 M-circle plus and a mean density of 6.0(-2.7)(+3.0) g cm(-3).
Published: 2017

23. Three Super-Earths Transiting the Nearby Star GJ 9827

Author: Niraula, Prajwal, Redfield, Seth, Dai, Fei, Barragan, Oscar, Gandolfi, Davide, Cauley, P. Wilson, Hirano, Teruyuki, Korth, Judith, Smith, Alexis M. S., Prieto-Arranz, Jorge, Grziwa, Sascha, Fridlund, Malcolm, Persson, Carina M., Justesen, Anders Bo, Winn, Joshua N., Albrecht, Simon, Cochran, William D., Csizmadia, Szilard, Duvvuri, Girish M., Endl, Michael, Hatzes, Artie P., Livingston, John H., Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Van Eylen, Vincent, Niraula, Prajwal, Redfield, Seth, Dai, Fei, Barragan, Oscar, Gandolfi, Davide, Cauley, P. Wilson, Hirano, Teruyuki, Korth, Judith, Smith, Alexis M. S., Prieto-Arranz, Jorge, Grziwa, Sascha, Fridlund, Malcolm, Persson, Carina M., Justesen, Anders Bo, Winn, Joshua N., Albrecht, Simon, Cochran, William D., Csizmadia, Szilard, Duvvuri, Girish M., Endl, Michael, Hatzes, Artie P., Livingston, John H., Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, and Van Eylen, Vincent
Abstract: We report on the discovery of three transiting planets around GJ. 9827. The planets have radii of 1.75 +/- 0.18, 1.36 +/- 0.14, and 2.11 (+0.22)(-0.21) R-circle plus, and periods of 1.20896, 3.6480, and 6.2014 days, respectively. The detection was made in Campaign 12 observations as part of our K2 survey of nearby stars. GJ 9827 is a V = 10.39 mag K6V star at a distance of 30.3 +/- 1.6 parsecs and the nearest star to be found hosting planets by Kepler and K2. The radial velocity follow- up, high- resolution imaging, and detection of multiple transiting objects near commensurability drastically reduce the false positive probability. The orbital periods of GJ 9827 b, c, and d planets are very close to the 1:3:5 mean motion resonance. Our preliminary analysis shows that GJ 9827 planets are excellent candidates for atmospheric observations. Besides, the planetary radii span both sides of the rocky and gaseous divide, hence the system will be an asset in expanding our understanding of the threshold.
Published: 2017

24. K2-60b and K2-107b. A Sub-Jovian and a Jovian Planet from the K2 Mission

Author: Eigmueller, Philipp, Gandolfi, Davide, Persson, Carina M., Donati, Paolo, Fridlund, Malcolm, Csizmadia, Szilard, Barragan, Oscar, Smith, Alexis M. S., Cabrera, Juan, Korth, Judith, Grziwa, Sascha, Prieto-Arranz, Jorge, Nespral, David, Saario, Joonas, Cochran, William D., Cusano, Felice, Deeg, Hans J., Endl, Michael, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Paetzold, Martin, Rauer, Heike, Eigmueller, Philipp, Gandolfi, Davide, Persson, Carina M., Donati, Paolo, Fridlund, Malcolm, Csizmadia, Szilard, Barragan, Oscar, Smith, Alexis M. S., Cabrera, Juan, Korth, Judith, Grziwa, Sascha, Prieto-Arranz, Jorge, Nespral, David, Saario, Joonas, Cochran, William D., Cusano, Felice, Deeg, Hans J., Endl, Michael, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Paetzold, Martin, and Rauer, Heike
Abstract: We report the characterization and independent detection of K2-60b, as well as the detection and characterization of K2-107b, two transiting hot gaseous planets from the K2 space mission. We confirm the planetary nature of the two systems and determine their fundamental parameters combining the K2 time-series data with FIES @ NOT and HARPS-N @ TNG spectroscopic observations. K2-60b has a radius of 0.683 +/- 0.037 R-Jup and a mass of 0.426 +/- 0.037 M-Jup and orbits a G4 V star with an orbital period of 3.00267 +/- 0.00006 days. K2-107b has a radius of 1.44 +/- 0.15 R-Jup and a mass of 0.84 +/- 0.08 M-Jup and orbits an F9 IV star every 3.31392 +/- 0.00002 days. K2-60b is among the few planets at the edge of the so-called desert of short-period sub-Jovian planets. K2107b is a highly inflated Jovian planet orbiting an evolved star about to leave the main sequence.
Published: 2017

25. EPIC 219388192b-An Inhabitant of the Brown Dwarf Desert in the Ruprecht 147 Open Cluster

Author: Nowak, Grzegorz, Palle, Enric, Gandolfi, Davide, Dai, Fei, Lanza, Antonino F., Hirano, Teruyuki, Barragan, Oscar, Fukui, Akihiko, Bruntt, Hans, Endl, Michael, Cochran, William D., Moroni, Pier G. Prada, Prieto-Arranz, Jorge, Kiilerich, Amanda, Nespral, David, Hatzes, Artie P., Albrecht, Simon, Deeg, Hans, Winn, Joshua N., Yu, Liang, Kuzuhara, Masayuki, Grziwa, Sascha, Smith, Alexis M. S., Guenther, Eike W., Van Eylen, Vincent, Csizmadia, Szilard, Fridlund, Malcolm, Cabrera, Juan, Eigmueller, Philipp, Erikson, Anders, Korth, Judith, Narita, Norio, Paetzold, Martin, Rauer, Heike, Ribas, Ignasi, Nowak, Grzegorz, Palle, Enric, Gandolfi, Davide, Dai, Fei, Lanza, Antonino F., Hirano, Teruyuki, Barragan, Oscar, Fukui, Akihiko, Bruntt, Hans, Endl, Michael, Cochran, William D., Moroni, Pier G. Prada, Prieto-Arranz, Jorge, Kiilerich, Amanda, Nespral, David, Hatzes, Artie P., Albrecht, Simon, Deeg, Hans, Winn, Joshua N., Yu, Liang, Kuzuhara, Masayuki, Grziwa, Sascha, Smith, Alexis M. S., Guenther, Eike W., Van Eylen, Vincent, Csizmadia, Szilard, Fridlund, Malcolm, Cabrera, Juan, Eigmueller, Philipp, Erikson, Anders, Korth, Judith, Narita, Norio, Paetzold, Martin, Rauer, Heike, and Ribas, Ignasi
Abstract: We report the discovery of EPIC 219388192b, a transiting brown dwarf in a 5.3 day orbit around a member star of Ruprecht 147, the oldest nearby open cluster association, which was photometrically monitored by K2 during its Campaign 7. We combine the K2 time-series data with ground-based adaptive optics imaging and high-resolution spectroscopy to rule out false positive scenarios and determine the main parameters of the system. EPIC 219388192b has a radius of R-b= 0.937 +/- 0.032 R-Jup and mass of M-b= 36.84 +/- 0.97 M-Jup, yielding a mean density of 59.6 +/- 7.6 g cm(- 3). The host star is nearly a solar twin with mass M-star = 1.01 +/- 0.04 Me, radius R-star = 1.01 +/- 0.03 R-circle dot, effective temperature T-eff = 5850 +/- 85 K, and iron abundance [Fe/ H]. = 0.03 +/- 0.08 dex. Its age, spectroscopic distance, and reddening are consistent with those of Ruprecht 147, corroborating its cluster membership. EPIC 219388192b is the first mature brown dwarf with precise determinations of mass, radius, and age, and serves as benchmark for evolutionary models in the substellar regime.
Published: 2017

26. The Transiting Multi-planet System HD3167: A 5.7M(circle plus) Super-Earth and an 8.3M(circle plus) Mini-Neptune

Author: Gandolfi, Davide, Barragan, Oscar, Hatzes, Artie P., Fridlund, Malcolm, Fossati, Luca, Donati, Paolo, Johnson, Marshall C., Nowak, Grzegorz, Prieto-Arranz, Jorge, Albrecht, Simon, Dai, Fei, Deeg, Hans, Endl, Michael, Grziwa, Sascha, Hjorth, Maria, Korth, Judith, Nespral, David, Saario, Joonas, Smith, Alexis M. S., Antoniciello, Giuliano, Alarcon, Javier, Bedell, Megan, Blay, Pere, Brems, Stefan S., Cabrera, Juan, Csizmadia, Szilard, Cusano, Felice, Cochran, William D., Eigmller, Philipp, Erikson, Anders, Gonzalez Hernandez, Jonay I., Guenther, Eike W., Hirano, Teruyuki, Suarez Mascareno, Alejandro, Narita, Norio, Palle, Enric, Parviainen, Hannu, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Saviane, Ivo, Schmidtobreick, Linda, Van Eylen, Vincent, Winn, Joshua N., Zakhozhay, Olga V., Gandolfi, Davide, Barragan, Oscar, Hatzes, Artie P., Fridlund, Malcolm, Fossati, Luca, Donati, Paolo, Johnson, Marshall C., Nowak, Grzegorz, Prieto-Arranz, Jorge, Albrecht, Simon, Dai, Fei, Deeg, Hans, Endl, Michael, Grziwa, Sascha, Hjorth, Maria, Korth, Judith, Nespral, David, Saario, Joonas, Smith, Alexis M. S., Antoniciello, Giuliano, Alarcon, Javier, Bedell, Megan, Blay, Pere, Brems, Stefan S., Cabrera, Juan, Csizmadia, Szilard, Cusano, Felice, Cochran, William D., Eigmller, Philipp, Erikson, Anders, Gonzalez Hernandez, Jonay I., Guenther, Eike W., Hirano, Teruyuki, Suarez Mascareno, Alejandro, Narita, Norio, Palle, Enric, Parviainen, Hannu, Paetzold, Martin, Persson, Carina M., Rauer, Heike, Saviane, Ivo, Schmidtobreick, Linda, Van Eylen, Vincent, Winn, Joshua N., and Zakhozhay, Olga V.
Abstract: HD3167 is a bright (V = 8.9 mag) K0V star observed by the NASA's K2 space mission during its Campaign 8. It has been recently found to host two small transiting planets, namely, HD 3167b, an ultra short period (0.96 days) super-Earth, and HD 3167c, a mini-Neptune on a relatively long-period orbit (29.85 d). Here we present an intensive radial velocity follow-up of HD 3167 performed with the FIES@NOT, HARPS@ESO-3.6m, and HARPS-N@TNG spectrographs. We revise the system parameters and determine radii, masses, and densities of the two transiting planets by combining the K2 photometry with our spectroscopic data. With a mass of 5.69 +/- -0.44 M-circle plus, radius of 1.574 +/- -0.054 R-circle plus, and mean density of 8.00(-0.98)(+1.0) g/cm(-3), HD 3167b joins the small group of ultra-short period planets known to have a rocky terrestrial composition. HD 3167c has a mass of 8.33(-1.85)(+1.79) M-circle plus and a radius of 2.740(-0.100)(+0.106) R-circle plus, yielding a mean density of 2.21(-0.53)(+0.56) g/cm(-3), indicative of a planet with a composition comprising a solid core surrounded by a thick atmospheric envelope. The rather large pressure scale height (similar to 350 km) and the brightness of the host star make HD 3167c an ideal target for atmospheric characterization via transmission spectroscopy across a broad range of wavelengths. We found evidence of additional signals in the radial velocity measurements but the currently available data set does not allow us to draw any firm conclusion on the origin of the observed variation.
Published: 2017

27. Three Super-Earths Transiting the Nearby Star GJ 9827

Author: Niraula, Prajwal, Redfield, Seth, Dai, Fei, Barragan, Oscar, Gandolfi, Davide, Cauley, P. Wilson, Hirano, Teruyuki, Korth, Judith, Smith, Alexis M. S., Prieto-Arranz, Jorge, Grziwa, Sascha, Fridlund, Malcolm, Persson, Carina M., Justesen, Anders Bo, Winn, Joshua N., Albrecht, Simon, Cochran, William D., Csizmadia, Szilard, Duvvuri, Girish M., Endl, Michael, Hatzes, Artie P., Livingston, John H., Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, Van Eylen, Vincent, Niraula, Prajwal, Redfield, Seth, Dai, Fei, Barragan, Oscar, Gandolfi, Davide, Cauley, P. Wilson, Hirano, Teruyuki, Korth, Judith, Smith, Alexis M. S., Prieto-Arranz, Jorge, Grziwa, Sascha, Fridlund, Malcolm, Persson, Carina M., Justesen, Anders Bo, Winn, Joshua N., Albrecht, Simon, Cochran, William D., Csizmadia, Szilard, Duvvuri, Girish M., Endl, Michael, Hatzes, Artie P., Livingston, John H., Narita, Norio, Nespral, David, Nowak, Grzegorz, Paetzold, Martin, Palle, Enric, and Van Eylen, Vincent
Abstract: We report on the discovery of three transiting planets around GJ. 9827. The planets have radii of 1.75 +/- 0.18, 1.36 +/- 0.14, and 2.11 (+0.22)(-0.21) R-circle plus, and periods of 1.20896, 3.6480, and 6.2014 days, respectively. The detection was made in Campaign 12 observations as part of our K2 survey of nearby stars. GJ 9827 is a V = 10.39 mag K6V star at a distance of 30.3 +/- 1.6 parsecs and the nearest star to be found hosting planets by Kepler and K2. The radial velocity follow- up, high- resolution imaging, and detection of multiple transiting objects near commensurability drastically reduce the false positive probability. The orbital periods of GJ 9827 b, c, and d planets are very close to the 1:3:5 mean motion resonance. Our preliminary analysis shows that GJ 9827 planets are excellent candidates for atmospheric observations. Besides, the planetary radii span both sides of the rocky and gaseous divide, hence the system will be an asset in expanding our understanding of the threshold.
Published: 2017

28. The Discovery and Mass Measurement of a New Ultra-short-period Planet: EPIC 228732031b

Author: Dai, Fei, Winn, Joshua N., Gandolfi, Davide, Wang, Sharon X., Teske, Johanna K., Burt, Jennifer, Albrecht, Simon, Barragan, Oscar, Cochran, William D., Endl, Michael, Fridlund, Malcolm, Hatzes, Artie P., Hirano, Teruyuki, Hirsch, Lea A., Johnson, Marshall C., Justesen, Anders Bo, Livingston, John, Persson, Carina M., Prieto-Arranz, Jorge, Vanderburg, Andrew, Alonso, Roi, Antoniciello, Giuliano, Arriagada, Pamela, Butler, R. P., Cabrera, Juan, Crane, Jeffrey D., Cusano, Felice, Csizmadia, Szilard, Deeg, Hans, Dieterich, Sergio B., Eigmueller, Philipp, Erikson, Anders, Everett, Mark E., Fukui, Akihiko, Grziwa, Sascha, Guenther, Eike W., Henry, Gregory W., Howell, Steve B., Johnson, John Asher, Korth, Judith, Kuzuhara, Masayuki, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Rauer, Heike, Montanes Rodriguez, Pilar, Shectman, Stephen A., Smith, Alexis M. S., Thompson, Ian B., Van Eylen, Vincent, Williamson, Michael W., Wittenmyer, Robert A., Dai, Fei, Winn, Joshua N., Gandolfi, Davide, Wang, Sharon X., Teske, Johanna K., Burt, Jennifer, Albrecht, Simon, Barragan, Oscar, Cochran, William D., Endl, Michael, Fridlund, Malcolm, Hatzes, Artie P., Hirano, Teruyuki, Hirsch, Lea A., Johnson, Marshall C., Justesen, Anders Bo, Livingston, John, Persson, Carina M., Prieto-Arranz, Jorge, Vanderburg, Andrew, Alonso, Roi, Antoniciello, Giuliano, Arriagada, Pamela, Butler, R. P., Cabrera, Juan, Crane, Jeffrey D., Cusano, Felice, Csizmadia, Szilard, Deeg, Hans, Dieterich, Sergio B., Eigmueller, Philipp, Erikson, Anders, Everett, Mark E., Fukui, Akihiko, Grziwa, Sascha, Guenther, Eike W., Henry, Gregory W., Howell, Steve B., Johnson, John Asher, Korth, Judith, Kuzuhara, Masayuki, Narita, Norio, Nespral, David, Nowak, Grzegorz, Palle, Enric, Paetzold, Martin, Rauer, Heike, Montanes Rodriguez, Pilar, Shectman, Stephen A., Smith, Alexis M. S., Thompson, Ian B., Van Eylen, Vincent, Williamson, Michael W., and Wittenmyer, Robert A.
Abstract: We report the discovery of a new ultra-short-period planet and summarize the properties of all such planets for which the mass and radius have been measured. The new planet, EPIC. 228732031b, was discovered in K2 Campaign 10. It has a radius of 1.81(-0.12)(+0.16) R-circle plus and orbits a G dwarf with a period of 8.9 hr. Radial velocities obtained with Magellan/PFS and TNG/HARPS-N show evidence for stellar activity along with orbital motion. We determined the planetary mass using two different methods: (1) the floating chunk offset method, based only on changes in velocity observed on the same night; and (2) a Gaussian process regression based on both the radial velocity and photometric time series. The results are consistent and lead to a mass measurement of 6.5. +/- 1.6 M-circle plus and a mean density of 6.0(-2.7)(+3.0) g cm(-3).
Published: 2017

29. K2-98b: A 32 M-circle plus NEPTUNE-SIZE PLANET IN A 10 DAY ORBIT TRANSITING AN F8 STAR

Author: Barragan, Oscar, Grziwa, Sascha, Gandolfi, Davide, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Cagigal, Manuel P., Lanza, Antonino F., Moroni, Pier G. Prada, Smith, Alexis M. S., Korth, Judith, Bedell, Megan, Cabrera, Juan, Cochran, William D., Cusano, Felice, Csizmadia, Szilard, Eigmueller, Philipp, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Nespral, David, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Barragan, Oscar, Grziwa, Sascha, Gandolfi, Davide, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Cagigal, Manuel P., Lanza, Antonino F., Moroni, Pier G. Prada, Smith, Alexis M. S., Korth, Judith, Bedell, Megan, Cabrera, Juan, Cochran, William D., Cusano, Felice, Csizmadia, Szilard, Eigmueller, Philipp, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Nespral, David, Paetzold, Martin, Prieto-Arranz, Jorge, and Rauer, Heike
Abstract: We report the discovery of K2-98b (EPIC 211391664b), a transiting Neptune-size planet monitored by the K2 mission during its Campaign 5. We combine the K2 time-series data with ground-based photometric and spectroscopic follow-up observations to confirm the planetary nature of the object and derive its mass, radius, and orbital parameters. K2-98b is a warm Neptune-like planet in a 10 day orbit around a V = 12.2 mag F-type star with M-star = 1.074 +/- 0.042 M-circle dot, R-star = 1.311(-0.048)(+0.083) R-circle dot, and age of 5.2(-1.0)(+1.2) Gyr We derive a planetary mass and radius of M-p = 32.2 +/- 8.1 M-circle plus and R-p = 4.3(-0.2)(+0.3) R-circle plus.K2-98b joins the relatively small group of Neptune-size planets whose mass and radius have been derived with a precision better than 25%. We estimate that the planet will be engulfed by its host star in similar to 3 Gyr, due to the evolution of the latter toward the red giant branch.
Published: 2016

30. K2-98b: A 32 M-circle plus NEPTUNE-SIZE PLANET IN A 10 DAY ORBIT TRANSITING AN F8 STAR

Author: Barragan, Oscar, Grziwa, Sascha, Gandolfi, Davide, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Cagigal, Manuel P., Lanza, Antonino F., Moroni, Pier G. Prada, Smith, Alexis M. S., Korth, Judith, Bedell, Megan, Cabrera, Juan, Cochran, William D., Cusano, Felice, Csizmadia, Szilard, Eigmueller, Philipp, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Nespral, David, Paetzold, Martin, Prieto-Arranz, Jorge, Rauer, Heike, Barragan, Oscar, Grziwa, Sascha, Gandolfi, Davide, Fridlund, Malcolm, Endl, Michael, Deeg, Hans J., Cagigal, Manuel P., Lanza, Antonino F., Moroni, Pier G. Prada, Smith, Alexis M. S., Korth, Judith, Bedell, Megan, Cabrera, Juan, Cochran, William D., Cusano, Felice, Csizmadia, Szilard, Eigmueller, Philipp, Erikson, Anders, Guenther, Eike W., Hatzes, Artie P., Nespral, David, Paetzold, Martin, Prieto-Arranz, Jorge, and Rauer, Heike
Abstract: We report the discovery of K2-98b (EPIC 211391664b), a transiting Neptune-size planet monitored by the K2 mission during its Campaign 5. We combine the K2 time-series data with ground-based photometric and spectroscopic follow-up observations to confirm the planetary nature of the object and derive its mass, radius, and orbital parameters. K2-98b is a warm Neptune-like planet in a 10 day orbit around a V = 12.2 mag F-type star with M-star = 1.074 +/- 0.042 M-circle dot, R-star = 1.311(-0.048)(+0.083) R-circle dot, and age of 5.2(-1.0)(+1.2) Gyr We derive a planetary mass and radius of M-p = 32.2 +/- 8.1 M-circle plus and R-p = 4.3(-0.2)(+0.3) R-circle plus.K2-98b joins the relatively small group of Neptune-size planets whose mass and radius have been derived with a precision better than 25%. We estimate that the planet will be engulfed by its host star in similar to 3 Gyr, due to the evolution of the latter toward the red giant branch.
Published: 2016

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30 results on '"Smith, Alexis M. S."'

1. TOI-1670 b and c: An Inner Sub-Neptune with an Outer Warm Jupiter Unlikely to Have Originated from High-eccentricity Migration

2. A Radial Velocity Study of the Planetary System of pi Mensae: Improved Planet Parameters for pi Mensae c and a Third Planet on a 125 Day Orbit

3. TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

4. It Takes Two Planets in Resonance to Tango around K2-146

5. The Multiplanet System TOI-421*

6. It Takes Two Planets in Resonance to Tango around K2-146

7. TOI-503: The First Known Brown-dwarf Am-star Binary from the TESS Mission

8. The Multiplanet System TOI-421*

9. The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap

10. The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap

11. K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths

12. Exoplanets around Low-mass Stars Unveiled by K2

13. Three Small Planets Transiting a Hyades Star

14. 44 Validated Planets from K2 Campaign 10

15. K2-155: A Bright Metal-poor M Dwarf with Three Transiting Super-Earths

16. Exoplanets around Low-mass Stars Unveiled by K2

17. Three Small Planets Transiting a Hyades Star

18. 44 Validated Planets from K2 Campaign 10

19. EPIC 219388192b-An Inhabitant of the Brown Dwarf Desert in the Ruprecht 147 Open Cluster

20. K2-60b and K2-107b. A Sub-Jovian and a Jovian Planet from the K2 Mission

21. The Transiting Multi-planet System HD3167: A 5.7M(circle plus) Super-Earth and an 8.3M(circle plus) Mini-Neptune

22. The Discovery and Mass Measurement of a New Ultra-short-period Planet: EPIC 228732031b

23. Three Super-Earths Transiting the Nearby Star GJ 9827

24. K2-60b and K2-107b. A Sub-Jovian and a Jovian Planet from the K2 Mission

25. EPIC 219388192b-An Inhabitant of the Brown Dwarf Desert in the Ruprecht 147 Open Cluster

26. The Transiting Multi-planet System HD3167: A 5.7M(circle plus) Super-Earth and an 8.3M(circle plus) Mini-Neptune

27. Three Super-Earths Transiting the Nearby Star GJ 9827

28. The Discovery and Mass Measurement of a New Ultra-short-period Planet: EPIC 228732031b

29. K2-98b: A 32 M-circle plus NEPTUNE-SIZE PLANET IN A 10 DAY ORBIT TRANSITING AN F8 STAR

30. K2-98b: A 32 M-circle plus NEPTUNE-SIZE PLANET IN A 10 DAY ORBIT TRANSITING AN F8 STAR

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30 results on '"Smith, Alexis M. S."'

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