Heartbeat stars are eccentric binaries exhibiting characteristic shape of brightness changes during periastron passage caused by tidal distortion of the components. Variable tidal potential can drive tidally excited oscillations (TEOs), which are usually gravity modes. Studies of heartbeat stars and TEOs open a new possibility to probe interiors of massive stars. There are only a few massive (masses of components $\gtrsim 2 $M$_\odot$) systems of this type known. Using TESS data from the first 16 sectors, we searched for new massive heartbeat stars and TEOs using a sample of over 300 eccentric spectroscopic binaries. We analysed TESS 2-min and 30-min cadence data. Then, we fitted Kumar's analytical model to the light curves of stars showing heartbeats and performed times-series analysis of the residuals searching for TEOs and periodic intrinsic variability. We found 20 massive heartbeat systems, of which seven show TEOs. The TEOs occur at harmonics of orbital frequencies in the range between 3 and 36, with the median value equal to 9, lower than those in known Kepler systems with TEOs. The most massive system in this sample is the quadruple star HD 5980, a member of Small Magellanic Cloud. With the total mass of $\sim$150 M$_{\odot}$ it is the most massive system showing a heartbeat. Six stars in the sample of the new heartbeat stars are eclipsing. Comparison of the parameters derived from fitting Kumar's model and from light-curve modelling shows that Kumar's model does not provide reliable parameters. Finally, intrinsic pulsations of $β$ Cep, SPB, $δ$ Sct, and $γ$ Dor-type were found in nine heartbeat systems. This opens an interesting possibility of studies of pulsation-binarity interaction and the co-existence of forced and self-excited oscillations.
Using ASAS-SN data, we find that the bright ($V{\sim}13.5$ mag) variable star MACHO 80.7443.1718 (ASASSN-V J052624.38-684705.6) is the most extreme heartbeat star yet discovered. This massive binary, consisting of at least one early B-type star, has an orbital period of $P_{\rm ASAS-SN}=32.83627\pm0.00846\,{\rm d},$ and is located towards the LH58 OB complex in the LMC. Both the ASAS-SN and TESS light curves show extreme brightness variations of ${\sim}40\%$ at periastron and variations of ${\sim}10\%$ due to tidally excited oscillations outside periastron. We fit an analytical model of the va…
We characterize the extreme heartbeat star system MACHO 80.7443.1718 in the LMC using TESS photometry and spectroscopic observations from the Magellan Inamori Kyocera Echelle (MIKE) and SOAR Goodman spectographs. MACHO 80.7443.1718 was first identified as a heartbeat star system in the All-Sky Automated Survey for SuperNovae (ASAS-SN) with $P_{\rm orb}=32.836\pm0.008\,{\rm d}$. MACHO 80.7443.1718 is a young (${\sim}6$~Myr), massive binary, composed of a B0 Iae supergiant with $M_1 \simeq 35 M_\odot$ and an O9.5V secondary with $M_2 \simeq 16 M_\odot$ on an eccentric ($e=0.51\pm0.03$) orbit. In…
Chemically peculiar stars in eclipsing binary systems are rare objects that allow the derivation of fundamental stellar parameters and important information on the evolutionary status and the origin of the observed chemical peculiarities. Here we present an investigation of the known eclipsing binary system BD+09 1467 = V680 Mon. Using spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and own observations, we identify the primary component of the system as a mercury-manganese (HgMn/CP3) star (spectral type kB9 hB8 HeB9 V HgMn). Furthermore, photometric time se…
We present 370 candidate eclipsing binaries (EBs), identified from ~510,000 short cadence TESS light curves. Our statistical criteria identify 5,105 light curves with features consistent with eclipses (~1% of the initial sample). After visual confirmation of the light curves, we have a final sample of 2,288 EB candidates. Among these, we find 370 sources that were not included in the catalog recently published by Prsa et al. We publish our full sample of 370 new EB candidates, and statistical features used for their identification, reported per observation sector.
Eccentric ellipsoidal variables (aka heartbeat stars) is a class of eccentric binaries in which proximity effects, tidal distortion due to time-dependent tidal potential in particular, lead to measurable photometric variability close to the periastron passage. The varying tidal potential may also give rise to tidally-excited oscillations (TEOs). TEOs may play an important role in the dynamical evolution of massive eccentric systems. Our study is aimed at the detection of TEOs and characterisation of the long-term behaviour of their amplitudes and frequencies in the extreme-amplitude heartbeat …
We analyse TESS light curves for 70 southern $λ$ Boo stars to identify binaries and to determine which of them pulsate as $δ$ Scuti stars. We find two heartbeat stars and two eclipsing binaries among the sample. We calculate that 81 percent of $λ$ Boo stars pulsate as $δ$ Sct variables, which is about twice that of normal stars over the same parameter space. We determine the temperatures and luminosities of the $λ$ Boo stars from photometry and Gaia DR2 parallaxes. A subset of 40 $λ$ Boo stars have 2-min TESS data, reliable temperatures and luminosities, and $δ$ Sct pulsation. We use Petersen …
In this paper we present a catalog of 4584 eclipsing binaries observed during the first two years (26 sectors) of the TESS survey. We discuss selection criteria for eclipsing binary candidates, detection of hither-to unknown eclipsing systems, determination of the ephemerides, the validation and triage process, and the derivation of heuristic estimates for the ephemerides. Instead of keeping to the widely used discrete classes, we propose a binary star morphology classification based on a dimensionality reduction algorithm. Finally, we present statistical properties of the sample, we qualitati…
This paper summarizes the project work on asteroseismology at the ERASMUS+ GATE 2020 Summer school on space satellite data. The aim was to do a global asteroseismic analysis of KIC 5006817 and quantify its stellar properties using the high-quality, state of the art space missions data. We employed the aperture photometry to analyze the data from the Kepler space telescope and the Transiting Exoplanet Survey Satellite (TESS). Using the lightkurve Python package, we have derived the asteroseismic parameters and calculated the stellar parameters using the scaling relations. Our analysis of KIC 50…
Lack of high-precision long-term continuous photometric data for large samples of stars has prevented the large-scale exploration of pulsational variability in the OB star regime. As a result, the candidates for in-depth asteroseismic modelling remained limited to a few tens of dwarfs. The TESS nominal space mission has surveyed the southern sky, yielding continuous data of at least 27 d for hundreds of OB stars. We aim to couple TESS data in the southern sky with spectroscopy to study the variability over mass and evolution. We focus mainly on the presence of coherent pulsation modes that may…
WR~21a was known as a massive spectroscopic binary composed of an O2.5 If*/WN6ha primary and an O3 V((f*))z secondary. Although a minimum value, the mass estimated for the primary placed it as one of the most massive stars found in our Galaxy. We report the discovery of photometric variations in the time series observations carried out by the Transiting Exoplanet Survey Satellite (TESS). These light variations are interpreted as formed by two main components: a sharp partial eclipse of the O3 secondary by the O2.5/WN6 star, and tidally excited oscillations. Based on the light minima a new ephe…
Pulsating B stars in the Scorpius-Centaurus Association with TESS
Indian Institute of Technology Roorkee（印度理工学院鲁尔基分校）；Sydney Institute for Astronomy, School of Physics, University of Sydney（悉尼大学物理学院天文研究所）；Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University（奥胡斯大学物理与天文学系恒星天体物理学中心）；Astronomical Institute, Graduate School of Science, Tohoku University（东北大学理学研究科天文学研究所）
Red giant asteroseismology can provide valuable information for studying the Galaxy as demonstrated by space missions like CoRoT and Kepler. However, previous observations have been limited to small data sets and fields-of-view. The TESS mission provides far larger samples and, for the first time, the opportunity to perform asteroseimic inference from full-frame images full-sky, instead of narrow fields and pre-selected targets. Here, we seek to detect oscillations in TESS data of the red giants in the Kepler field using the 4-yr Kepler results as benchmark. Because we use 1-2 sectors of obser…
Diverse Variability of O and B Stars Revealed from 2-minute Cadence Light Curves in Sectors 1 and 2 of the TESS Mission: Selection of an Asteroseismic Sample
The TESS space mission is producing superb data for asteroseismology, eclipsing binary stars, gyrochronology, and other fields of stellar astronomy where the data are variable light curves. We show that TESS data are excellent for astrophysical inference from peculiar stars that show variability. The Ap stars have the strongest magnetic fields of any main-sequence stars. Some have been shown to have rotation periods of months to centuries. The astrophysical cause of their slow rotation -- the braking mechanism -- is not known with certainty. These stars are rare: there are currently about 3 do…
Binary stars are crucial laboratories for stellar physics, so have been photometric targets for space missions beginning with the very first orbiting telescope (OAO-2) launched in 1968. This review traces the binary stars observed and the scientific results obtained from the early days of ultraviolet missions (OAO-2, Voyager, ANS, IUE), through a period of diversification (Hipparcos, WIRE, MOST, BRITE), to the current era of large planetary transit surveys (CoRoT, Kepler, TESS). In this time observations have been obtained of detached, semi-detached and contact binaries containing dwarfs, sub-…
We report the discovery of 74 new pulsating DA white dwarf stars, or ZZ Cetis, from the data obtained by the Transiting Exoplanet Survey Satellite (TESS) mission, from Sectors 1 to 39, corresponding to the first 3 cycles. This includes objects from the Southern Hemisphere (Sectors 1-13 and 27-39) and the Northern Hemisphere (Sectors 14-26), observed with 120 s- and 20 s-cadence. Our sample likely includes 13 low-mass and one extremely low-mass white dwarf candidate, considering the mass determinations from fitting Gaia magnitudes and parallax. In addition, we present follow-up time series phot…
We present High-Level Science Products (HLSPs) containing light curves from MIT's Quick-Look Pipeline (QLP) from the second year of TESS' first Extended Mission (Sectors 40 - 55; 2021 July - 2022 September). In total, 12.2 million per-sector light curves for 5.7 million unique stars were extracted from 10-minute cadence Full-Frame Images (FFIs) and are made available to the community. As in previous deliveries, QLP HLSPs include both raw and detrended flux time series for all observed stars brighter than TESS magnitude T = 13.5 mag. Starting in Sector 41, QLP also produces light curves for sel…
AU Mic is a young ($\sim$24 Myr), pre-Main Sequence M~dwarf star that was observed in the first month of science observations of the Transiting Exoplanet Survey Satellite (TESS) and re-observed two years later. This target has photometric variability from a variety of sources that is readily apparent in the TESS light curves; spots induce modulation in the light curve, flares are present throughout (manifesting as sharp rises with slow exponential decay phases), and transits of AU Mic b may be seen by eye as dips in the light curve. We present a combined analysis of both TESS Sector 1 and Sect…
The TESS space mission provides us with high-precision photometric observations of bright stars over more than 70% of the entire sky, allowing us to revisit and characterise well-known stars. We aim to conduct an asteroseismic analysis of the gamma Doradus star HD112429 using both the available ground-based spectroscopy and TESS photometry, and assess the conditions required to measure the near-core rotation rate and buoyancy travel time. We collect and reduce the available five sectors of short-cadence TESS photometry of this star, as well as 672 legacy observations from six medium- to high-r…
Since the end of 2018, the Transiting Exoplanet Survey Satellite (TESS) provides high-quality space data on stellar photometry to the astronomical community. We present the results of an analysis of TESS photometric data for known slowly rotating magnetic chemically peculiar (mCP) stars. In general, mCP stars show an inhomogeneous distribution of elements in their stellar atmospheres that leads to spectroscopic (line profile) and photometric (light curve) variations over the rotation period. In the frame of the oblique magnetic rotator (OMR) model, patches of enhanced chemical abundance on the…
We present a magnitude-limited set of lightcurves for stars observed over the TESS Extended Mission, as extracted from full-frame images (FFIs) by MIT's Quick-Look Pipeline (QLP). QLP uses multi-aperture photometry to produce lightcurves for ~1 million stars each 27.4-day sector, which are then searched for exoplanet transits. The per-sector lightcurves for 9.1 million unique targets observed over the first year of the Extended Mission (Sectors 27 - 39) are available as High-Level Science Products (HLSP) on the Mikulski Archive for Space Telescopes (MAST). As in our TESS Primary Mission QLP HL…
From sector 1--44 {\em TESS} observations, 19 new roAp stars, 103 ostensibly non-peculiar stars with roAp-like frequencies and 617 $δ$~Scuti stars with independent frequencies typical of roAp stars were found. Examination of all chemically peculiar stars observed by {\em TESS} resulted in the discovery of 199 Ap stars which pulsate as $δ$~Sct or $γ$~Dor variables. The fraction of pulsating Ap stars is the same as the fraction of pulsating chemically normal stars. There is no distinct separation in frequency or radial order between chemically peculiar $δ$~Sct stars and roAp stars. In fact, all …
In this work, we present the analysis of 33,054 M-dwarf stars located within 100 parsecs in the Transiting Exoplanet Survey Satellite (TESS) Full Frame Images (FFIs) of the observed sectors 1 to 5. We present a new pipeline called NEMESIS which was developed to extract detrended photometry and perform transit searches of single sector data in TESS FFIs. As many M-dwarfs are faint and are not observed with a 2 minute cadence by TESS, FFI transit surveys can give an empirical validation of how many planets are missed by using the 30 minute cadence data. In this work, we detected 183 threshold cr…
Identifying 850 delta Scuti pulsators in a narrow Gaia colour range with TESS 10-minute full-frame images
Sydney Institute for Astronomy, School of Physics, University of Sydney（悉尼大学物理学院天体物理研究所）；School of Physics, University of New South Wales（新南威尔士大学物理学院）；UNSW Data Science Hub, University of New South Wales（新南威尔士大学数据科学中心）；Institute for Astronomy, University of Hawai‘i（夏威夷大学天体物理研究所）；Centre for Astrophysics, University of Southern Queensland（南昆士兰大学天体物理学中心）
Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) - I. First-light observations of known magnetic B and A stars
We present the first analysis of Cepheid stars observed by the TESS space mission in Sectors 1 to 5. Our sample consists of 25 pulsators: ten fundamental mode, three overtone and two double-mode classical Cepheids, plus three Type II and seven anomalous Cepheids. The targets were chosen from fields with different stellar densities, both from the Galactic field and from the Magellanic System. Three targets have 2-minute cadence light curves available by the TESS Science Processing Operations Center: for the rest, we prepared custom light curves from the full-frame images with our own differenti…
TESS (Transiting Exoplanet Survey Satellite) was launched in 2018 with the purpose of observing bright stars in the solar neighbourhood to search for transiting exoplanets. After the completion of the two year nominal mission, TESS has provided 2\,minute cadence photometry of over 200\,000 stars. This large collection of light curves opens the possibility to study the statistical and temporal properties of this ensemble of stars. Most of the currently available data pipelines are designed to work on single sector at a time. We present a new TESS data pipeline called {\tt Taranga}, with the pur…
We present a catalog of 97 uniformly-vetted candidates for quadruple star systems. The candidates were identified in TESS Full Frame Image data from Sectors 1 through 42 through a combination of machine learning techniques and visual examination, with major contributions from a dedicated group of citizen scientists. All targets exhibit two sets of eclipses with two different periods, both of which pass photocenter tests confirming that the eclipses are on-target. This catalog outlines the statistical properties of the sample, nearly doubles the number of known multiply-eclipsing quadruple syst…
Light curves of 57 classical Be stars in TESS sectors 1 - 15 are examined. In most Be stars, the periodogram shows groups at a fundamental and one or more harmonics, which we attribute to rotation. In about 40 percent of the stars, the group is just a single narrow or slightly broadened peak. In about 30 percent, it consists of a multiple, closely spaced peaks. These groups can be interpreted as non-coherent variations most likely associated with photospheric gas clouds. Approximate rotational frequencies for about 75 percent of the stars can be derived. Comparison with the projected rotationa…
Short Term Variability of Evolved Massive Stars with TESS
我们提出的第一个结果，从TESS部门1和2的光变曲线的研究，在大麦哲伦星系的8个演变的大质量恒星：6个黄色超巨星（YSG）和两个明亮的蓝色变量（LBV），包括S剑鱼座。我们使用迭代预白化过程来表征所有八颗恒星的短时间尺度变化。其中一个YSG HD 269953的周期图显示出多个强峰，频率高于其他恒星。虽然HD 269953周围的区域相当拥挤，但它是该区域最明亮的恒星，并且具有红外颜色，表明它是尘埃。我们认为HD 269953可能处于后红超巨星演化阶段。我们发现LBV HD 269582的信号周期为$\sim5$天。剑鱼座S的周期图显示了一个复杂的结构，峰值低于每天1.5个周期的频率。我们拟合了所有八个光变曲线的背景噪声的形状，并在所有光变曲线中找到了红噪声分量。然而，红噪声的幂律斜率和相干结构产生的时间尺度因恒星而异。我们的研究结果突出了用TESS研究演化的大质量恒星的潜力。
