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27 results on '"J. A. Brown"'

1. GOALS-JWST: Gas Dynamics and Excitation in NGC 7469 Revealed by NIRSpec

Author

Marina Bianchin, Vivian U, Yiqing Song, Thomas S.-Y. 劭愉 Lai 賴, Raymond P. Remigio, Loreto Barcos-Muñoz, Tanio Díaz-Santos, Lee Armus, Hanae Inami, Kirsten L. Larson, Aaron S. Evans, Torsten Böker, Justin A. Kader, Sean T. Linden, Vassilis Charmandaris, Matthew A. Malkan, Jeff Rich, Thomas Bohn, Anne M. Medling, Sabrina Stierwalt, Joseph M. Mazzarella, David R. Law, George C. Privon, Susanne Aalto, Philip Appleton, Michael J. I. Brown, Victorine A. Buiten, Luke Finnerty, Christopher C. Hayward, Justin Howell, Kazushi Iwasawa, Francisca Kemper, Jason Marshall, Jed McKinney, Francisco Müller-Sánchez, Eric J. Murphy, Paul P. van der Werf, David B. Sanders, and Jason Surace

Published
2024
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2. GOALS-JWST: Small Neutral Grains and Enhanced 3.3 μm PAH Emission in the Seyfert Galaxy NGC 7469

Author

Thomas S.-Y. 劭愉 Lai 賴, Lee Armus, Marina Bianchin, Tanio Díaz-Santos, Sean T. Linden, George C. Privon, Hanae Inami, Vivian U, Thomas Bohn, Aaron S. Evans, Kirsten L. Larson, Brandon S. Hensley, J.-D. T. Smith, Matthew A. Malkan, Yiqing Song, Sabrina Stierwalt, Paul P. van der Werf, Jed McKinney, Susanne Aalto, Victorine A. Buiten, Jeff Rich, Vassilis Charmandaris, Philip Appleton, Loreto Barcos-Muñoz, Torsten Böker, Luke Finnerty, Justin A. Kader, David R. Law, Anne M. Medling, Michael J. I. Brown, Christopher C. Hayward, Justin Howell, Kazushi Iwasawa, Francisca Kemper, Jason Marshall, Joseph M. Mazzarella, Francisco Müller-Sánchez, Eric J. Murphy, David Sanders, and Jason Surace

Published
2023
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4. ASASSN-18am/SN 2018gk: an overluminous Type IIb supernova from a massive progenitor

Author

Subhash Bose, Subo Dong, C S Kochanek, M D Stritzinger, Chris Ashall, Stefano Benetti, E Falco, Alexei V Filippenko, Andrea Pastorello, Jose L Prieto, Auni Somero, Tuguldur Sukhbold, Junbo Zhang, Katie Auchettl, Thomas G Brink, J S Brown, Ping Chen, A Fiore, Dirk Grupe, T W-S Holoien, Peter Lundqvist, Seppo Mattila, Robert Mutel, David Pooley, R S Post, Naveen Reddy, Thomas M Reynolds, Benjamin J Shappee, K Z Stanek, Todd A Thompson, S Villanueva, and WeiKang Zheng

Published
2021
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6. A hot mini-Neptune in the radius valley orbiting solar analogue HD 110113

Author

H P Osborn, D J Armstrong, V Adibekyan, K A Collins, E Delgado-Mena, S B Howell, C Hellier, G W King, J Lillo-Box, L D Nielsen, J F Otegi, N C Santos, C Ziegler, D R Anderson, C Briceño, C Burke, D Bayliss, D Barrado, E M Bryant, D J A Brown, S C C Barros, F Bouchy, D A Caldwell, D M Conti, R F Díaz, D Dragomir, M Deleuil, O D S Demangeon, C Dorn, T Daylan, P Figueira, R Helled, S Hoyer, J M Jenkins, E L N Jensen, D W Latham, N Law, D R Louie, A W Mann, A Osborn, D L Pollacco, D R Rodriguez, B V Rackham, G Ricker, N J Scott, S G Sousa, S Seager, K G Stassun, J C Smith, P Strøm, S Udry, J Villaseñor, R Vanderspek, R West, P J Wheatley, and J N Winn

Published
2021
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8. Mass determinations of the three mini-Neptunes transiting TOI-125

Author

L D Nielsen, D Gandolfi, D J Armstrong, J S Jenkins, M Fridlund, N C Santos, F Dai, V Adibekyan, R Luque, J H Steffen, M Esposito, F Meru, S Sabotta, E Bolmont, D Kossakowski, J F Otegi, F Murgas, M Stalport, F Rodler, M R Díaz, N T Kurtovic, G Ricker, R Vanderspek, D W Latham, S Seager, J N Winn, J M Jenkins, R Allart, J M. Almenara, D Barrado, S C C Barros, D Bayliss, Z M Berdiñas, I Boisse, F Bouchy, P Boyd, D J A Brown, E M Bryant, C Burke, W D Cochran, B F Cooke, O D S Demangeon, R F Díaz, J Dittman, C Dorn, X Dumusque, R A García, L González-Cuesta, S Grziwa, I Georgieva, N Guerrero, A P Hatzes, R Helled, C E Henze, S Hojjatpanah, J Korth, K W F Lam, J Lillo-Box, T A Lopez, J Livingston, S Mathur, O Mousis, N Narita, H P Osborn, E Palle, P A Peña Rojas, C M Persson, S N Quinn, H Rauer, S Redfield, A Santerne, L A dos Santos, J V Seidel, S G Sousa, E B Ting, M Turbet, S Udry, A Vanderburg, V Van Eylen, J I Vines, P J Wheatley, and P A Wilson

Published
2020
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9. GOALS-JWST: Pulling Back the Curtain on the AGN and Star Formation in VV 114

Author

J. Rich, S. Aalto, A. S. Evans, V. Charmandaris, G. C. Privon, T. Lai, H. Inami, S. Linden, L. Armus, T. Diaz-Santos, P. Appleton, L. Barcos-Muñoz, T. Böker, K. L. Larson, D. R. Law, M. A. Malkan, A. M. Medling, Y. Song, V. U, P. van der Werf, T. Bohn, M. J. I. Brown, L. Finnerty, C. Hayward, J. Howell, K. Iwasawa, F. Kemper, J. Marshall, J. M. Mazzarella, J. McKinney, F. Muller-Sanchez, E. J. Murphy, D. Sanders, B. T. Soifer, S. Stierwalt, and J. Surace

Published
2023
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10. GOALS-JWST: Resolving the Circumnuclear Gas Dynamics in NGC 7469 in the Mid-infrared

Author

Vivian U, Thomas Lai, Marina Bianchin, Raymond P. Remigio, Lee Armus, Kirsten L. Larson, Tanio Díaz-Santos, Aaron Evans, Sabrina Stierwalt, David R. Law, Matthew A. Malkan, Sean Linden, Yiqing Song, Paul P. van der Werf, Tianmu Gao, George C. Privon, Anne M. Medling, Loreto Barcos-Muñoz, Christopher C. Hayward, Hanae Inami, Jeff Rich, Susanne Aalto, Philip Appleton, Thomas Bohn, Torsten Böker, Michael J. I. Brown, Vassilis Charmandaris, Luke Finnerty, Justin Howell, Kazushi Iwasawa, Francisca Kemper, Jason Marshall, Joseph M. Mazzarella, Jed McKinney, Francisco Muller-Sanchez, Eric J. Murphy, David Sanders, and Jason Surace

Published
2022
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11. TESS and HARPS reveal two sub-Neptunes around TOI 1062

Author

J. F. Otegi, F. Bouchy, R. Helled, D. J. Armstrong, M. Stalport, A. Psaridi, J.-B. Delisle, K.G. Stassun, E. Delgado-Mena, N. C. Santos, N. C. Hara, K. Collins, S. Gandhi, C. Dorn, M. Brogi, M. Fridlund, H. P. Osborn, S. Hoyer, S. Udry, S. Hojjatpanah, L. D. Nielsen, X. Dumusque, V. Adibekyan, D. Conti, R. Schwarz, G. Wang, P. Figueira, J. Lillo-Box, A. Hadjigeorghiou, D. Bayliss, P. A. Strøm, S. G. Sousa, D. Barrado, A. Osborn, S. C. C. Barros, D. J. A. Brown, J. D. Eastman, D. R. Ciardi, A. Vanderburg, R. F. Goeke, N. M. Guerrero, P. T. Boyd, D. A. Caldwell, C. E. Henze, B. McLean, G. Ricker, R. Vanderspek, D. W. Latham, S. Seager, J. Winn, and J. M. Jenkins

Subjects
Astronomy, Astrophysics
Abstract

The Transiting Exoplanet Survey Satellite (TESS) mission was designed to perform an all-sky search of planets around bright and nearby stars. Here we report the discovery of two sub-Neptunes orbiting around TOI 1062 (TIC 299799658), a V = 10.25 G9V star observed in the TESS Sectors 1, 13, 27, and 28. We use precise radial velocity observations from HARPS to confirm and characterize these two planets. TOI 1062b has a radius of 2.265(-0.091,+0.096) Rꚛ, a mass of 10.15 ± 0.8 Mꚛ, and an orbital period of 4.1130 ± 0.0015 days. The second planet is not transiting, has a minimum mass of 9.78(−1.18,+1.26) Mꚛ and is near the 2:1 mean motion resonance with the innermost planet with an orbital period of 7.972(−0.024,+0.018) days. We performed a dynamical analysis to explore the proximity of the system to this resonance, and to attempt further constraining the orbital parameters. The transiting planet has a mean density of 4.85(−0.74,+0.84) g/cu. cm and an analysis of its internal structure reveals that it is expected to have a small volatile envelope accounting for 0.35% of the mass at most. The star’s brightness and the proximity of the inner planet to what is know as the radius gap make it an interesting candidate for transmission spectroscopy, which could further constrain the composition and internal structure of TOI 1062b.

Published
2021
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15. The ASAS-SN bright supernova catalogue – IV. 2017

Author

T W-S Holoien, J S Brown, P J Vallely, K Z Stanek, C S Kochanek, B J Shappee, J L Prieto, Subo Dong, J Brimacombe, D W Bishop, S Bose, J F Beacom, D Bersier, Ping Chen, L Chomiuk, E Falco, S Holmbo, T Jayasinghe, N Morrell, G Pojmanski, J V Shields, J Strader, M D Stritzinger, Todd A Thompson, P R Woźniak, G Bock, P Cacella, J G Carballo, I Cruz, E Conseil, R G Farfan, J M Fernandez, S Kiyota, R A Koff, G Krannich, P Marples, G Masi, L A G Monard, J A Muñoz, B Nicholls, R S Post, G Stone, D L Trappett, and W S Wiethoff

Published
2019
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16. The Chandra Deep Wide-field Survey: A New Chandra Legacy Survey in the Bootes Field. I. X-ray Point Source Catalog, Number Counts, and Multiwavelength Counterparts

Author

Alberto Masini, Ryan C. Hickox, Christopher M. Carroll, James Aird, David M. Alexander, Roberto J. Assef, Richard Bower, Mark Brodwin, Michael J. I. Brown, Suchetana Chatterjee, Chien-ting J Chen, Arjun Dey, Michael A. DiPompeo, Kenneth J. Duncan, Peter R Eisenhardt, William R. Forman, Anthony H. Gonzalez, Andrew D. Goulding, Kevin N Hainline, Buell T. Jannuzi, Christine Jones, Christopher S. Kochanek, Ralph Kraft, Kyoung-Soo Lee, Eric D. Miller, James Mullaney, Adam D. Myers, Andrew Francis Ptak, Adam Stanford, Daniel K Stern, Alexey Vikhlinin, David A. Wake, and Stephen S. Murray

Subjects
Astronomy
Abstract

We present a new, ambitious survey performed with the Chandra X-ray Observatory of the 9.3 deg2 Boötes field of the NOAO Deep Wide-Field Survey. The wide field probes a statistically representative volume of the universe at high redshift. The Chandra Deep Wide-field Survey exploits the excellent sensitivity and angular resolution of Chandra over a wide area, combining 281 observations spanning 15 yr, for a total exposure time of 3.4 Ms, and detects 6891 X-ray point sources down to limiting fluxes of 4.7 × 10−16, 1.5 × 10−16, and 9 × 10−16 erg cm−2 s−1 in the 0.5–7, 0.5–2, and 2–7 keV bands, respectively. The robustness and reliability of the detection strategy are validated through extensive, state-of-the-art simulations of the whole field. Accurate number counts, in good agreement with previous X-ray surveys, are derived thanks to the uniquely large number of point sources detected, which resolve 65.0% ± 12.8% of the cosmic X-ray background between 0.5 and 2 keV and 81.0% ± 11.5% between 2 and 7 keV. Exploiting the wealth of multiwavelength data available on the field, we assign redshifts to ∼94% of the X-ray sources, estimate their obscuration, and derive absorption-corrected luminosities. We provide an electronic catalog containing all of the relevant quantities needed for future investigations.

Published
2020
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17. A remnant planetary core in the hot-Neptune desert

Author

David J. Armstrong, Théo A. Lopez, Vardan Adibekyan, Richard A. Booth, Edward M. Bryant, Karen A. Collins, Magali Deleuil, Alexandre Emsenhuber, Chelsea X. Huang, George W. King, Jorge Lillo-Box, Jack J. Lissauer, Elisabeth Matthews, Olivier Mousis, Louise D. Nielsen, Hugh Osborn, Jon Otegi, Nuno C. Santos, Sérgio G. Sousa, Keivan G. Stassun, Dimitri Veras, Carl Ziegler, Jack S. Acton, Jose M. Almenara, David R. Anderson, David Barrado, Susana C. C. Barros, Daniel Bayliss, Claudia Belardi, Francois Bouchy, César Briceño, Matteo Brogi, David J. A. Brown, Matthew R. Burleigh, Sarah L. Casewell, Alexander Chaushev, Kevin I. Collins, Knicole D. Colón, Benjamin F. Cooke, Ian J. M. Crossfield, Rodrigo F. Díaz, Elisa Delgado Mena, Olivier D. S. Demangeon, Caroline Dorn, Xavier Dumusque, Philipp Eigmüller, Michael Fausnaugh, Pedro Figueira, Tianjun Gan, Siddharth Gandhi, Samuel Gill, Erica J. Gonzales, Michael R. Goad, Ravit Helled, Saeed Hojjatpanah, Steve B. Howell, James Jackman, James S. Jenkins, Jon M. Jenkins, Eric L. N. Jensen, Grant M. Kennedy, David W. Latham, Nicholas Law, Monika Lendl, Michael Lozovsky, Andrew W. Mann, Maximiliano Moyano, James McCormac, Farzana Meru, Christoph Mordasini, Ares Osborn, Don Pollacco, Didier Queloz, Liam Raynard, George R. Ricker, Pamela Rowden, Alexandre Santerne, Joshua E. Schlieder, Sara Seager, Lizhou Sha, Thiam-Guan Tan, Rosanna H. Tilbrook, Eric Ting, Stéphane Udry, Roland Vanderspek, Christopher A. Watson, Richard G. West, Paul A. Wilson, Joshua N. Winn, Peter Wheatley, Jesus Noel Villasenor, Jose I. Vines, and Zhuchang Zhan

Subjects
Exobiology, Lunar And Planetary Science And Exploration
Abstract

The interiors of giant planets remain poorly understood. Even for the planets in the Solar System, difficulties in observation lead to large uncertainties in the properties of planetary cores. Exoplanets that have undergone rare evolutionary processes provide a route to understanding planetary interiors. Planets found in and near the typically barren hot-Neptune ‘desert’ (a region in mass–radius space that contains few planets) have proved to be particularly valuable in this regard. These planets include HD149026b, which is thought to have an unusually massive core, and recent discoveries such as LTT9779b and NGTS-4b, on which photoevaporation has removed a substantial part of their outer atmospheres. Here we report observations of the planet TOI-849b, which has a radius smaller than Neptune’s but an anomalously large mass of 39.1(+2.7−2.6) Earth masses and a density of 5.2(+0.7−0.8) grams per cubic centimetre, similar to Earth’s. Interior-structure models suggest that any gaseous envelope of pure hydrogen and helium consists of no more than 3.9(+0.8−0.9) per cent of the total planetary mass. The planet could have been a gas giant before undergoing extreme mass loss via thermal self-disruption or giant planet collisions, or it could have avoided substantial gas accretion, perhaps through gap opening or late formation. Although photoevaporation rates cannot account for the mass loss required to reduce a Jupiter-like gas giant, they can remove a small (a few Earth masses) hydrogen and helium envelope on timescales of several billion years, implying that any remaining atmosphere on TOI-849b is likely to be enriched by water or other volatiles from the planetary interior. We conclude that TOI-849b is the remnant core of a giant planet.

Published
2020
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18. Large Ocean Worlds with High-Pressure Ices

Author

Baptiste Journaux, Klára Kalousová, Christophe Sotin, Gabriel Tobie, Steve Vance, Joachim Saur, Olivier Bollengier, Lena Noack, Tina Rückriemen-Bez, Tim Van Hoolst, Krista M. Soderlund, and J. Michael Brown

Published
2020
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20. The Magellan-TESS Survey. I. Survey Description and Midsurvey Results* †

Author

Johanna Teske, Sharon Xuesong Wang, Angie Wolfgang, Tianjun Gan, Mykhaylo Plotnykov, David J. Armstrong, R. Paul Butler, Bryson Cale, Jeffrey D. Crane, Ward Howard, Eric L. N. Jensen, Nicholas Law, Stephen A. Shectman, Peter Plavchan, Diana Valencia, Andrew Vanderburg, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Vardan Adibekyan, David Barrado, Susana C. C. Barros, Zouhair Benkhaldoun, David J. A. Brown, Edward M. Bryant, Jennifer Burt, Douglas A. Caldwell, David Charbonneau, Ryan Cloutier, Karen A. Collins, Kevin I. Collins, Knicole D. Colon, Dennis M. Conti, Olivier D. S. Demangeon, Jason D. Eastman, Mohammed Elmufti, Fabo Feng, Erin Flowers, Natalia M. Guerrero, Saeed Hojjatpanah, Jonathan M. Irwin, Giovanni Isopi, Jorge Lillo-Box, Franco Mallia, Bob Massey, Mayuko Mori, Susan E. Mullally, Norio Narita, Taku Nishiumi, Ares Osborn, Martin Paegert, Jerome Pitogo de Leon, Samuel N. Quinn, Michael Reefe, Richard P. Schwarz, Avi Shporer, Abderahmane Soubkiou, Sérgio G. Sousa, Chris Stockdale, Paul A. Strøm, Thiam-Guan Tan, Jiaxin Tang, Peter Tenenbaum, Peter J. Wheatley, Justin Wittrock, Daniel A. Yahalomi, and Farzaneh Zohrabi

Published
2021
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21. Discovery of Highly Blueshifted Broad Balmer and Metastable Helium Absorption Lines in a Tidal Disruption Event

Author

T Hung, S B Cenko, Nathaniel Roth, S Gezari, S Veilleux, Sjoert van Velzen, C Martin Gaskell, Ryan J Foley, N Blagorodnova, Lin Yan, M J Graham, J S Brown, M R Siebert, Sara Frederick, Charlotte Ward, Pradip Gatkine, Avishay Gal-Yam, Yi Yang, S Schulze, G Dimitriadis, Thomas Kupfer, David L Shupe, Ben Rusholme, Frank J Masci, Reed Riddle, Maayane T Soumagnac, J van Roestel, and Richard Dekany

Subjects
Astronomy
Abstract

We report the discovery of nonstellar hydrogen Balmer and metastable helium absorption lines accompanying a transient, high-velocity (0.05c) broad absorption line (BAL) system in the optical spectra of the tidal disruption event (TDE) AT2018zr (z = 0.071). In the Hubble Space Telescope UV spectra, absorption of high- and low-ionization lines is also present at this velocity, making AT2018zr resemble a low-ionization BALQSO. We conclude that these transient absorption features are more likely to arise in fast outflows produced by the TDE than absorbed by the unbound debris. In accordance with the outflow picture, we are able to reproduce the flat-topped Hα emission in a spherically expanding medium without invoking the typical prescription of an elliptical disk. We also report the appearance of narrow (∼1000 kms−1) N III λ4640, He II λ4686, Hα, and Hβ emission in the latetime optical spectra of AT2018zr, which may be a result of UV continuum hardening at late times, as observed by Swift. Including AT2018zr, we find a high association rate (three out of four) of BALs in the UV spectra of TDEs. This suggests that outflows may be ubiquitous among TDEs and less sensitive to viewing angle effects compared to QSO outflows.

Published
2019
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22. The Young Supernova Experiment: Survey Goals, Overview, and Operations

Author

D. O. Jones, R. J. Foley, G. Narayan, J. Hjorth, M. E. Huber, P. D. Aleo, K. D. Alexander, C. R. Angus, K. Auchettl, V. F. Baldassare, S. H. Bruun, K. C. Chambers, D. Chatterjee, D. L. Coppejans, D. A. Coulter, L. DeMarchi, G. Dimitriadis, M. R. Drout, A. Engel, K. D. French, A. Gagliano, C. Gall, T. Hung, L. Izzo, W. V. Jacobson-Galán, C. D. Kilpatrick, H. Korhonen, R. Margutti, S. I. Raimundo, E. Ramirez-Ruiz, A. Rest, C. Rojas-Bravo, M. R. Siebert, S. J. Smartt, K. W. Smith, G. Terreran, Q. Wang, R. Wojtak, A. Agnello, Z. Ansari, N. Arendse, A. Baldeschi, P. K. Blanchard, D. Brethauer, J. S. Bright, J. S. Brown, T. J. L. de Boer, S. A. Dodd, J. R. Fairlamb, C. Grillo, A. Hajela, C. Cold, A. N. Kolborg, J. A. P. Law-Smith, C.-C. Lin, E. A. Magnier, K. Malanchev, D. Matthews, B. Mockler, D. Muthukrishna, Y.-C. Pan, H. Pfister, D. K. Ramanah, S. Rest, A. Sarangi, S. L. Schrøder, C. Stauffer, M. C. Stroh, K. L. Taggart, S. Tinyanont, and R. J. Wainscoat

Published
2021
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23. Seeing Double: ASASSN-18bt Exhibits a Two-component Rise in the Early-time K2 Light Curve

Author

B. J. Shappee, T. W.-S. Holoien, M. R. Drout, K. Auchettl, M. D. Stritzinger, C. S. Kochanek, K. Z. Stanek, E. Shaya, G. Narayan, J. S. Brown, S. Bose, D. Bersier, J. Brimacombe, Ping Chen, Subo Dong, S. Holmbo, B. Katz, J. A. Munoz, R. L. Mutel, R. S. Post, J. L. Prieto, J. Shields, D. Tallon, T. A. Thompson, P. J. Vallely, S. Villanueva Jr, L. Denneau, H. Flewelling, A. N. Heinze, K. W. Smith, B. Stalder, J. L. Tonry, H. Weiland, T. Barclay, G. Barentsen, A. M. Cody, J. Dotson, F. Foerster, P. Garnavich, M. Gully-Santiago, C. Hedges, S. Howell, D. Kasen, S. Margheim, R. Mushotzky, A. Rest, B. E. Tucker, A. Villar, A. Zenteno, G. Beerman, R. Bjella, G. Castillo, J. Coughlin, B. Elsaesser, S. Flynn, R. Gangopadhyay, K. Griest, M. Hanley, J. Kampmeier, R. Kloetzel, L. Kohnert, C. Labonde, R. Larsen, K. A. Larson, K. M. McCalmont-Everton, C. McGinn, L. Migliorini, J. Moffatt, M. Muszynski, V. Nystrom, D. Osborne, M. Packard, C. A. Peterson, M. Redick, L. H. Reedy, S. E. Ross, B. Spencer, K. Steward, J. E. Van Cleve, J. Vinícius de Miranda-Cardoso, T. Weschler, A. Wheaton, J. Bulger, K. C. Chambers, H. A. Flewelling, M. E. Huber, T. B. Lowe, E. A. Magnier, A. S. B. Schultz, C. Z. Waters, M. Willman, E. Baron, Zhihao Chen, James M. Derkacy, Fang Huang, Linyi Li, Wenxiong Li, Xue Li, Jun Mo, Liming Rui, Hanna Sai, Lifan Wang, Lingzhi Wang, Xiaofeng Wang, Danfeng Xiang, Jicheng Zhang, Jujia Zhang, Kaicheng Zhang, Tianmeng Zhang, Xinghan Zhang, Xulin Zhao, P. J. Brown, J. J. Hermes, J. Nordin, S. Points, A. Sodor, and G. M. Strampelli

Subjects
Astrophysics
Abstract

On 2018 February 4.41, the All-Sky Automated Survey for SuperNovae (ASAS-SN) discovered ASASSN-18bt in the K2 Campaign 16 field. With a redshift of z=0.01098 and a peak apparent magnitude of B(max)=14.31, ASASSN-18bt is the nearest and brightest SNe Ia yet observed by the Kepler spacecraft. Here we present the discovery of ASASSN-18bt, the K2 light curve, and prediscovery data from ASAS-SN and the Asteroid Terrestrial-impact Last Alert System. The K2 early-time light curve has an unprecedented 30-minute cadence and photometric precision for an SN Ia light curve, and it unambiguously shows a ∼4 day nearly linear phase followed by a steeper rise. Thus, ASASSN-18bt joins a growing list of SNe Ia whose early light curves are not well described by a single power law. We show that a double-power-law model fits the data reasonably well, hinting that two physical processes must be responsible for the observed rise. However, we find that current models of the interaction with a nondegenerate companion predict an abrupt rise and cannot adequately explain the initial, slower linear phase. Instead, we find that existing published models with shallow 56Ni are able to span the observed behavior and, with tuning, may be able to reproduce the ASASSN-18bt light curve. Regardless, more theoretical work is needed to satisfactorily model this and other early-time SNe Ia light curves. Finally, we use Swift X-ray nondetections to constrain the presence of circumstellar material (CSM) at much larger distances and lower densities than possible with the optical light curve. For a constant-density CSM, these nondetections constrain ρ<4.5×10(exp 5)per cu.cm at a radius of 4×10(exp 15) cm from the progenitor star. Assuming a wind-like environment, we place mass loss limits of M˙ < 8 x 10(exp -6) M(ʘ)per yr for v(w)=100 km/s, ruling out some symbiotic progenitor systems. This work highlights the power of well-sampled early-time data and the need for immediate multiband, high-cadence follow-up for progress in understanding SNe Ia.

Published
2018
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24. Photometric and Spectroscopic Properties of Type Ia Supernova 2018oh with Early Excess Emission from the Kepler 2 Observations

Author

Thomas Barclay, W. Li, X. Wang, J. Vinko, J. Mo, G. Hosseinzadeh, D. J. Sand, J. Zhang, H. Lin, T. Zhang, L. Wang, Z. Chen, D. Xiang, L. Rui, F. Huang, X. Li, X. Zhang, L. Li, E. Baron, J. M. Derkacy, X. Zhao, H. Sai, K. Zhang, D. A. Howell, C. McCully, I. Arcavi, S. Valenti, D. Hiramatsu, J. Burke, A. Rest, P. Garnavich, B. E. Tucker, G. Narayan, E. Shaya, S. Margheim, A. Zenteno, A. Villar, G. Dimitriadis, R. J. Foley, Y.-C. Pan, D. A. Coulter, O. D. Fox, S. W. Jha, D. O. Jones, D. N. Kasen, C. D. Kilpatrick, A. L. Piro, A. G. Riess, C. Rojas-Bravo, B. J. Shappee, T. W.-S. Holoien, K. Z. Stanek, M. R. Drout, K. Auchettl, C. S. Kochanek, J. S. Brown, S. Bose, D. Bersier, J. Brimacombe, P. Chen, S. Dong, S. Holmbo, J. A. Munoz, R. L. Mutel, R. S. Post, J. L. Prieto, J. Shields, D. Tallon, T. A. Thompson, P. J. Vallely, S. Villanueva Jr, S. J. Smartt, K. W. Smith, K. C. Chambers, H. A. Flewelling, M. E. Huber, E. A. Magnier, C. Z. Waters, A. S. B. Schultz, J. Bulger, T. B. Lowe, M. Willman, K. Sarneczky, A. Pal, J. C. Wheeler, A. Bodi, Zs. Bognar, B. Csak, B. Cseh, G. Csornyei, O. Hanyecz, B. Ignacz, Cs. Kalup, R. Konyves-Toth, L. Kriskovics, A. Ordasi, I. Rajmon5, A. Sodor, R. Szabo, R. Szakats, G. Zsidi, P. Milne, J. E. Andrews, N. Smith, C. Bilinski, P. J. Brown, J. Nordin, S. C. Williams, L. Galbany, J. Palmerio, I. M. Hook, C. Inserra, K. Maguire, Regis Cartier, A. Razza, C. P. Gutierrez, J. J. Hermes, J. S. Reding, B. C. Kaiser, J. L. Tonry, A. N. Heinze, L. Denneau, H. Weiland, B. Stalder, G. Barentsen, J Dotson, T Barclay, M Gully-Santiago, C. Hedges, A. M. Cody, S Howell, J. Coughlin, J. E. Van Cleve, J. Vinicius de Miranda Cardoso, K. A. Larson, K. M. McCalmont-Everton, C. A. Peterson, S. E. Ross, L. H. Reedy, D. Osborne, C. McGinn, L. Kohnert, L. Migliorini, A. Wheaton, B. Spencer, C. Labonde, G. Castillo, G. Beerman, K. Steward, M. Hanley, R. Larsen, R. Gangopadhyay, R. Kloetzel, T. Weschler, V. Nystrom, J. Moffatt, M. Redick, K. Griest, M. Packard, M. Muszynski, J. Kampmeier, R. Bjella, S. Flynn, and B. Elsaesser

Subjects
Astrophysics, Astronomy
Abstract

Supernova (SN) 2018oh (ASASSN-18bt) is the first spectroscopically confirmed Type Ia supernova (SN Ia) observed in the Kepler field. The Kepler data revealed an excess emission in its early light curve, allowing us to place interesting constraints on its progenitor system. Here we present extensive optical, ultraviolet, and nearinfrared photometry, as well as dense sampling of optical spectra, for this object. SN 2018oh is relatively normal in its photometric evolution, with a rise time of 18.3±0.3 days and Δ(m15)(B)=0.96±0.03 mag, but it seems to have bluer B−V colors. We construct the “UVOIR” bolometric light curve having a peak luminosity of 1.49×10(Exp 43) erg/s, from which we derive a nickel mass as 0.55±0.04M(ʘ) by fitting radiation diffusion models powered by centrally located 56Ni. Note that the moment when nickel-powered luminosity starts to emerge is +3.85 days after the first light in the Kepler data, suggesting other origins of the early-time emission, e.g., mixing of 56Ni to outer layers of the ejecta or interaction between the ejecta and nearby circumstellar material or a nondegenerate companion star. The spectral evolution of SN 2018oh is similar to that of a normal SN Ia but is characterized by prominent and persistent carbon absorption features. The CII features can be detected from the early phases to about 3 weeks after the maximum light, representing the latest detection of carbon ever recorded in an SN Ia. This indicates that a considerable amount of unburned carbon exists in the ejecta of SN 2018oh and may mix into deeper layers.

Published
2018
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25. The XXL Survey

Author

Arya Farahi, Valentina Guglielmo, August E. Evrard, Bianca M. Poggianti, Christophe Adami, Stefano Ettori, Fabio Gastaldello, Paul A. Giles, Ben J. Maughan, David Rapetti, Mauro Sereno, Bruno Altieri, Ivan Baldry, Mark Birkinshaw, Micol Bolzonella, Angela Bongiorno, Michael J. I. Brown, Lucio Chiappetti, Simon P. Driver, Andrii Elyiv, Bianca Garilli, Loïc Guennou, Andrew Hopkins, Angela Iovino, Elias Koulouridis, Jochen Liske, Sophie Maurogordato, Matthew Owers, Florian Pacaud, Marguerite Pierre, Manolis Plionis, Trevor Ponman, Aaron Robotham, Tatyana Sadibekova, Marco Scodeggio, Richard Tuffs, and Ivan Valtchanov

Published
2018
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