Search

One of the most cost-effective, accurate, and cheap methods for radial velocity measurements is the usage of the gas absorption cell (e.g., Iodine cell) method. We present new open-access software for processing spectra obtained with gas cells, the python-based program Viper (Velocity and IP EstimatoR), and recent results obtained with it. It can be used for data obtained with gas cell from multiple instruments (e.g., OES, TCES, CRIRES+) and new can be easily added. When this method was tested on Ondřejov Echelle Spectrograph data, the achieved rms improved 6 times compared to a classic cross-correlation method. Viper is still under development. One of the new features we are currently working on is employing telluric lines that allow us to use Viper for the analysis without a gas cell.

Poster forThe Impact of Binaries on Stellar Evolution workshop

The TESS and Gaia missions are both collecting data of exquisite quality for RR Lyrae-type pulsating stars. We combine light curve shape information from TESS with distances and brightnesses from Gaia to build a detailed classification scheme that is able to filter out intrinsically fainter binaries and rotational variables as well as short-period Cepheids that otherwise have light curves very similar to that of RR Lyrae stars, while preserving targets with unusual light curve shapes. We build a clean sample from the RR Lyrae stars in the vicinity of the Sun, out to 5-10 kpc distances. Based on the TESS light curves we find that a large fraction of RR Lyrae stars exhibit various additional low-amplitude modes. The distribution of extra modes in period is markedly different from that of stars within the bulge and globular clusters, signaling a metallicity dependence in the mode periods and excitation mechanisms. We also detect a possible dependence of extra modes from color and hence effective temperatures in overtone RRc stars. While these new results have brought us closer to true asteroseismic analysis of RR Lyrae stars, we show through new échelle-type diagrams that mode identification is still hindered by the strong influence of the radial mode(s) dominating the pulsation., {"references":["Bovy, J., et al., 2016, ApJ, 818, 130","Gaia Collaboration, 2021, A&A, 649, 1","Jurcsik, J., et al., 2015, ApJS, 219, 25","Molnár, L., et al., 2017, EpJ WoC, 160, 04008","Netzel, H., et al., 2019, MNRAS, 487, 5584","Pál, A., 2012, MNRAS, 421, 1825","Smolec, R., et al., 2017, MNRAS, 467, 2349"]}

We present preliminary results of the identification of the variable stars brighter than 11 mag among A- and F-type stars in the northern TESS continuous viewing zone (CVZ). The aim of our efforts is to identify good candidates for the spectroscopic follow-up observations. We found out that about 63 % of all stars show some kind of variability. About one-third of the investigated stars shows a combination of variability types., {"references":["Dupret et al. (2005), A&A, 435, 927","Murphy et al. (2014), MNRAS, 441, 2515,","Murphy et al. (2019), MNRAS, 485, 2380","Stassun et al. (2019), AJ, 158, 138","Skarka et al. (2019), MNRAS, 487, 4230","Paunzen et al. (2020), MNRAS, 499, 3976","Watson et al. (2006), 25th Annual Symposium, The Society for Astronomical Sciences, 47"]}

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 Echellé Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Échelle 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 Pb = 5.19672 ± 0.00049 days, a mass of Mb = 7.17 ± 0.66 M⊕, and a radius of Rb = ${2.68}_{-0.18}^{+0.19}$ R⊕, whereas the outer warm Neptune, TOI-421 c, has a period of Pc = 16.06819 ± 0.00035 days, a mass of Mc = ${16.42}_{-1.04}^{+1.06}$ M⊕, a radius of Rc = ${5.09}_{-0.15}^{+0.16}$ R⊕, and a density of ρc = ${0.685}_{-0.072}^{+0.080}$ g cm-3. With its characteristics, the outer planet (ρc = ${0.685}_{-0.072}^{+0.080}$ g 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 Lyα 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. * Based on observations made with ESO Telescopes at the La Silla Observatory under programs ID 1102.C-0923, 0103.C-0874, 0103.C-0759, 0103.C-0442, and 60.A-970. Based on observations obtained with the Nordic Optical Telescope (NOT), operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos (ORM) of the Instituto de Astrofísica de Canarias (IAC). This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. This work makes use of observations from the LCOGT network.

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 . We obtained high-resolution spectroscopic observations with the FIES, Ondrejov, PARAS, Tautenburg, and TRES spectrographs, and measured the mass of TOI-503b to be M b = 53.7 ± 1.2 a radius of R = 1.70 ± 0.05R o, an effective temperature of T eff = 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 main-sequence 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 is reforesting., J.Š. and P.K. would like to acknowledge the support from GACR international grant 17-01752J. J.Š. would like to acknowledge the support from source 116-09/260441, Institute of Theoretical Physics, Charles University in Prague, Czech Republic. J.K., S.G., M.P., S.C., A.P.H., H.R., M.E., and K.W.F. L. acknowledge support by Deutsche Forschungsgemeinschaft (DFG) grants PA525/18-1, PA525/19-1, PA525/20-1, HA 3279/12-1, and RA 714/14-1 within the DFG Schwerpunkt SPP 1992, Exploring the Diversity of Extrasolar Planets. S.C. acknowledges the Hungarian Scientific Research Fund (OTKA) Grant KH-130372. This work is partly supported by JSPS KAKENHI grant Nos. JP18H01265 and JP18H05439, and JST PRESTO grant No. JPMJPR1775. S.M. acknowledges support by the Spanish Ministry through the Ramon y Cajal fellowship number RYC-2015-17697. R.A.G. acknowledges the support from the PLATO/CNES grant. M.S. acknowledges the Postdoc@MUNI project CZ.02.2.69/0.0/0.0/16-027/0008360. S. M. acknowledges support from the ERC SPIRE 647383 grant. M.F., C.M.P., and I.G. gratefully acknowledge the support of the Swedish National Space Agency (DNR 163/16 and 174/18). K. G.S. acknowledges partial support from NASA grant 17-XRP17 2-0024. This paper includes data collected by the Kepler mission. Funding for the Kepler mission is provided by the NASA Science Mission directorate. Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST). STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofísica de Canarias. Also based in part on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program P103.C-0449. T.W.C. would like to acknowledge the effort of the observers who acquired the ground-based photometry at FLWO, LCO, CHAT, and FLI as part of the TESS Follow-up Program. Thanks to Alex J. Mustill and Scott Gaudi for useful discussions. The PARAS spectrograph is fully funded and being supported by Physical Research Laboratory (PRL), which is part of Department of Space, Government of India. R.S. and A.C. would like to thank Director P.R.L. for his support and acknowledges the help from Vishal Shah and the Mount Abu Observatory staff at the time of observations. A.C. is grateful to Suvrath Mahadevan from Pennsylvania State University and Arpita Roy from Caltech, for their tremendous efforts in the development of the PARAS data pipeline.

The \textit{Kepler} space telescope observed thousands of RR Lyrae stars in the K2 mission. In this paper we present our photometric solutions using extended apertures in order to conserve the flux of the stars to the highest possible extent. With this method we are able to avoid most of the problems that RR Lyrae light curves produced by other pipelines suffer from. For post-processing we apply the K2SC pipeline to our light curves. We provide the EAP (Extended Aperture Photometry) of 432 RR Lyrae stars observed in campaigns 3, 4, 5, and 6. We also provide subclass classifications based on Fourier parameters. We investigated in particular the presence of the Blazhko effect in the stars, and found it to be 44.7\% among the RRab stars, in agreement with results from independent samples. We found that the amplitude and phase modulation in the Blazhko stars may behave rather differently, at least over the length of a K2 Campaign. We also identified four anomalous Cepheid candidates in the sample one of which is potentially the first Blazhko-modulated member of its class., 20 pages, 13 figures, accepted in ApJS, light curves available at https://konkoly.hu/KIK/data_en.html

An ensemble of 50 candidate hybrid A/F-type stars from the Kepler mission was monitored during four years with the HERMES spectrograph attached to the Mercator telescope. From this survey, we obtained new radial velocities, new or improved atmospheric properties (Teff, log g, v sin i), and classified all our targets in terms of evidence for multiplicity, pulsation and/or fast rotation. An extension of 40 new candidate hybrid A- and F-type stars from the Kepler mission has been recently defined for a second survey to be performed under similar conditions. The new high-resolution spectra will be obtained with various small and medium-sized telescopes. For a number of newly detected stellar systems with good radial velocity coverage, we also computed much improved orbits by combining the radial velocities with the time delays obtained via the monitoring of the pulsation frequencies during the four years of Kepler photometry., {"references":["Balona, L. A. 2018, MNRAS, 476, 4840","Balona, L. A., Daszyńska-Daszkiewicz, J., & Pamyatnykh, A. A. 2015, MNRAS, 452, 3073","Grigahcène, A., Antoci, V., Balona, L., Catanzaro, G., Daszyńska-Daszkiewicz, J., et al. 2010, ApJ, 713, L192","Irwin, J. B. 1952, ApJ, 116, 211","Koubský, P., Mayer, P., Čáp, J., Žďárský, F., Zeman, J., et al. 2004, Publications of the Astronomical Institute of the Czechoslovak Academy of Sciences, 92, 37","Lampens, P., Frémat, Y., Vermeylen, L., Sódor, Á., Skarka, M., et al. 2018, A&A, 610, A17","Murphy, S. J. & Shibahashi, H. 2015, MNRAS, 450, 4475","Nemec, J. M., Balona, L. A., Murphy, S. J., Kinemuchi, K., & Jeon, Y.-B. 2017, MNRAS, 466, 1290","Raskin, G., van Winckel, H., Hensberge, H., Jorissen, A., Lehmann, H., et al. 2011, A&A, 526, A69","Reyniers, K. & Smeyers, P. 2003, A&A, 404, 1051","Shibahashi, H., Murphy, S. J., & Kurtz, D. W. 2016, IAU Focus Meeting, 29, 642","Uytterhoeven, K., Moya, A., Grigahcène, A., Guzik, J. A., Gutiérrez-Soto, J., et al. 2011, A&A, 534, A125"]}

We report the discovery of two massive eccentric systems with BRITE data, $\tau$ Ori and $\tau$ Lib, showing heartbeat effects close to the periastron passage. $\tau$ Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected., Comment: 3 pages, 1 figure, to appear in the Proceedings of the 3rd BRITE Science Conference

We report on a study of 250 optical spectra for 50 bright A/F-type candidate hybrid pulsating stars from the Kepler field. Most of the spectra have been collected with the high-resolution spectrograph HERMES attached to the Mercator telescope, La Palma. We determined the radial velocities (RVs), projected rotational velocities, fundamental atmospheric parameters and provide a classification based on the appearance of the cross-correlation profiles and the behaviour of the RVs with time in order to find true hybrid pulsators. Additionally, we also detected new spectroscopic binary and multiple systems in our sample and determined the fraction of spectroscopic systems. In order to be able to extend this investigation to the fainter A-F type candidate hybrid stars, various high-quality spectra collected with 3–4 m sized telescopes suitably equipped with a high-resolution spectrograph and furthermore located in the Northern hemisphere would be ideal. This programme could be done using the new instruments installed at the Devasthal Observatory.

We report the discovery of two massive eccentric systems with BRITE data, tau Ori and tau Lib, showing heartbeat effects close to the periastron passage. tau Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected.

We report the discovery of two massive eccentric systems with BRITE data, $��$ Ori and $��$ Lib, showing heartbeat effects close to the periastron passage. $��$ Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected., 3 pages, 1 figure, to appear in the Proceedings of the 3rd BRITE Science Conference

We present the first release of the Czech Variable star catalogue that currently contains 1228 stars whose variability was discovered by 60 Czech observers. The catalogue contains confirmed variable stars of various types, but also candidates. We give precise coordinates, cross identification with other catalogues, information about constellation, variability type, brightness, light elements, name of the discoverer and year of discovery. In eighty-eight percent of stars the variability type is estimated, for more than 60 % of the stars the light ephemerides are given., 42 pages, 4 tables, 2 figures, Published in OEJV

We present an overview and current status of research on RR Lyrae stars in binary systems. In present days the number of binary candidates has steeply increased and suggested that multiple stellar systems with an RR Lyrae component is much higher than previously thought. We discuss the probability of their detection using various observing methods, compare recent results regarding selection effects, period distribution, proposed orbital parameters and the Blazhko effect., 4 pages, 2 figures, proceedings of RRL2015 - High-Precision Studies of RR Lyrae Stars, to appear in the Communications from the Konkoly Observatory of the Hungarian Academy of Sciences

A paper about variable stars with possible multiple occurrence in the VSX catalogue is presented. Our main criteria for identification of such duplicities were the angular distance among stars (below 1 arcmin) and close periods of objects. In our approach, we also considered double or half values of periods to reveal possible misclassification among stars with similar light curve shapes. The probability of false identification is expressed by the parameter R giving the relative difference between periods. We found 1487 pairs of stars in angular distance lower than 1 arcmin with period difference R lower than 0.1 %, which are high-probable candidates on duplicates. From this sample, 354 pairs have exactly the same periods (R = 0.0 %) and should be considered as definite duplicates. The main contribution of certain duplicates comes from the Catalina Sky Survey (73 pairs have two names with CSS acronym) and from the BEST projects (71 pairs). Distribution of identified duplicates on the sky is not homogeneous but contains surprising depression in Galactic plane., Published in OEJV, 11 pages, 10 figures