TESS Data for Asteroseismology: Timing verification
Carolina von Essen, Mikkel N. Lund, Rasmus Handberg, Marina S. Sosa, Julie Thiim Gadeberg, Hans Kjeldsen, Roland K. Vanderspek, Dina S. Mortensen, M. Mallonn, L… 展开作者
Carolina von Essen, Mikkel N. Lund, Rasmus Handberg, Marina S. Sosa, Julie Thiim Gadeberg, Hans Kjeldsen, Roland K. Vanderspek, Dina S. Mortensen, M. Mallonn, L. Mammana, Edward H. Morgan, Jesus Noel S. Villasenor, Michael M. Fausnaugh, George R. Ricker
The Transiting Exoplanet Survey Satellite (TESS) is NASA's latest space telescope dedicated to the discovery of transiting exoplanets around nearby stars. Besides the main goal of the mission, asteroseismology is an important secondary goal and very relevant for the high-quality time series that TESS will make during its two year all-sky survey. Using TESS for asteroseismology introduces strong timing requirements, especially for coherent oscillators. Although the internal clock on board TESS is precise in its own time, it might have a constant drift and will thus need calibration, or offsets might inadvertently be introduced. Here we present simultaneously ground- and space-based observations of primary eclipses of several binary systems in the Southern ecliptic hemisphere, used to verify the reliability of the TESS timestamps. From twelve contemporaneous TESS/ground observations we determined a time offset equal to 5.8 +/- 2.5 sec, in the sense that the Barycentric time measured by TESS is ahead of real time. The offset is consistent with zero at 2.3-sigma level. In addition, we used 405 individually measured mid-eclipse times of 26 eclipsing binary stars observed solely by TESS to test the existence of a potential drift with a monotonic growth (or decay) affecting the observations of all stars. We find a drift corresponding to sigma_drift = 0.009 +/- 0.015 sec/day. We find that the measured offset is of a size that will not become an issue for comparing ground-based and space data for coherent oscillations for most of the targets observed with TESS.
The perfect 30-min cadence of the full-frame images from the Transiting Exoplanet Survey Satellite (TESS) will impose a hard Nyquist limit of 24 d$^{-1}$ ($\approx 278$ $μ$Hz). This will be problematic for asteroseismology of stars with oscillation frequencies at or around that Nyquist limit, which will have insurmountable Nyquist ambiguities. TESS does offer some observing slots at shorter cadences, but these will be limited in number and competitive, while the full frame images will be the main data product for many types of variable stars. We show that the Nyquist ambiguities can be allevia…
Space-based asteroseismology has been playing an important role in the characterization of exoplanet-host stars and their planetary systems. The future looks even brighter, with space missions such as NASA's TESS and ESA's PLATO ready to take on this legacy. In this contribution, we provide an outlook on the synergy between asteroseismology and exoplanet science, namely, on the prospect of conducting a populational study of giant planets around oscillating evolved stars with the TESS mission.
The Transiting Exoplanet Survey Satellite (TESS) is observing bright known planet-host stars across almost the entire sky. These stars have been subject to extensive ground-based observations, providing a large number of radial velocity (RV) measurements. In this work we use the new TESS photometric observations to characterize the star $λ^2$ Fornacis, and following this to update the parameters of the orbiting planet $λ^2$ For b. We measure the p-mode oscillation frequencies in $λ^2$ For, and in combination with non-seismic parameters estimate the stellar fundamental properties using stellar …
Data from the Transiting Exoplanet Survey Satellite (TESS) has produced of order one million light curves at cadences of 120 s and especially 1800 s for every ~27-day observing sector during its two-year nominal mission. These data constitute a treasure trove for the study of stellar variability and exoplanets. However, to fully utilize the data in such studies a proper removal of systematic noise sources must be performed before any analysis. The TESS Data for Asteroseismology (T'DA) group is tasked with providing analysis-ready data for the TESS Asteroseismic Science Consortium, which covers…
Asteroseismology of bright stars has become increasingly important as a method to determine fundamental properties (in particular ages) of stars. The Kepler Space Telescope initiated a revolution by detecting oscillations in more than 500 main-sequence and subgiant stars. However, most Kepler stars are faint, and therefore have limited constraints from independent methods such as long-baseline interferometry. Here, we present the discovery of solar-like oscillations in $α$ Men A, a naked-eye (V=5.1) G7 dwarf in TESS's Southern Continuous Viewing Zone. Using a combination of astrometry, spectro…
We present an analysis of the first 20-second cadence light curves obtained by the TESS space telescope during its extended mission. We find a precision improvement of 20-second data compared to 2-minute data for bright stars when binned to the same cadence (~10-25% better for T<~8 mag, reaching equal precision at T~13 mag), consistent with pre-flight expectations based on differences in cosmic ray mitigation algorithms. We present two results enabled by this improvement. First, we use 20-second data to detect oscillations in three solar analogs (gamma Pav, zeta Tuc and pi Men) and use asteros…
Asteroseismology is among the most powerful observational tools to determine fundamental properties of stars. Space-based photometry has recently enabled the systematic detection of oscillations in exoplanet host stars, allowing a combination of asteroseismology with transit and radial-velocity measurements to characterize planetary systems. In this contribution I will review the key synergies between asteroseismology and exoplanet science such as the precise determination of radii and ages of exoplanet host stars, as well as applications of asteroseismology to measure spin-orbit inclinations …
A precise transit ephemeris serves as the premise for follow-up exoplanet observations. We compare TESS Objects of Interest (TOI) transit timings of 262 hot Jupiters with the archival ephemeris and find 31 of them having TOI timing offsets, among which WASP-161b shows the most significant offset of -203.7$\pm$4.1 minutes. The median value of these offsets is 17.8 minutes, equivalent to 3.6 $σ$. We generate TESS timings in each sector for these 31 hot Jupiters, using a self-generated pipeline. The pipeline performs photometric measurements to TESS images and produces transit timings by fitting …
We provide a database of transit times and updated ephemerides for 382 planets based on data from the NASA Transiting Exoplanet Survey Satellite (TESS) and previously reported transit times which were scraped from the literature in a semi-automated fashion. In total, our database contains 8,667 transit timing measurements for 382 systems. About 240 planets in the catalog are hot Jupiters (i.e. planets with mass $>$0.3$M_{\rm Jup}$ and period $<$10 days) that have been observed by TESS. The new ephemerides are useful for scheduling follow-up observations and searching for long-term period chang…
We identify targets in the Kepler field that may be characterized by transit timing variations (TTVs) and are detectable by the Transiting Exoplanet Survey Satellite (TESS). Despite the reduced signal-to-noise ratio of TESS transits compared to Kepler, we recover 48 transits from 13 systems in Sectors 14, 15, 26, 40 and 41. We find strong evidence of a nontransiting perturber orbiting Kepler-396 (KOI-2672) and explore two possible cases of a third planet in that system that could explain the measured transit times. We update the ephemerides and mass constraints where possible at KOI-70 (Kepler…
Asteroseismology has grown from its beginnings three decades ago to a mature field teeming with discoveries and applications. This phenomenal growth has been enabled by space photometry with precision $10-100$ times better than ground-based observations, with nearly continuous light curves for durations of weeks to years, and by large scale ground-based surveys spanning years designed to detect all time-variable phenomena. The new high precision data are full of surprises, deepening our understanding of the physics of stars. $\bullet$ This review explores asteroseismic developments from the la…
Early-type main-sequence pulsating stars such as \ds{} variables are one of the least explored class of targets in the search for exoplanets. Pulsation timing (PT) is an alternative technique to the most effective search methods. It exploits the light-travel-time effect (LTTE) to infer the presence of additional massive bodies around a pulsating star by measuring a periodic phase modulation of its signal. PT has been extremely successful in discovering and characterizing stellar binaries when it was applied to high-precision light curves over long temporal baselines, such as those delivered by…
We report on the detection of transit timing variations (TTV) of WASP-161b by using the combination of TESS data and archival data. The midpoint of the transits in TESS data are offset by $\sim$67 minutes in Jan. 2019, and $\sim$203 minutes in Jan. 2021, based on the ephemeris published in previous work. We are able to reproduce the transit timings from the archival light curve (SSO-Europa; Jan. 2018) and find SSO-Europa timing is consistent with the published ephemeris under a constant period assumption. Conversely, we find that the SSO-Europa transit midpoint indicates a 6.62-minute variatio…
The study of planet occurrence as a function of stellar mass is important for a better understanding of planet formation. Estimating stellar mass, especially in the red giant regime, is difficult. In particular, stellar masses of a sample of evolved planet-hosting stars based on spectroscopy and grid-based modelling have been put to question over the past decade with claims they were overestimated. Although efforts have been made in the past to reconcile this dispute using asteroseismology, results were inconclusive. In an attempt to resolve this controversy, we study four more evolved planet-…
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…
From previous ground-based observations, the hot Jupiter exoplanet XO-6b was reported to exhibit apparently periodic transit timing variations (TTVs), with a semi-amplitude of 14 minutes and a period of about 450 days. These variations were interpreted as being due to a resonant perturbation between XO-6b and a hitherto unknown low-mass planet orbiting the same star. To understand this enigmatic planetary system better, we analysed three sectors of data, spanning over seven months, from the Transiting Exoplanet Survey Satellite (TESS), which produces high-quality light curves that are well sui…
The angle between the rotation and orbital axes of stars in binary systems -- the obliquity -- is an important indicator of how these systems form and evolve but few such measurements exist. We combine the sample of astrometric orbital inclinations from Gaia DR3 with a sample of solar-like oscillators in which rotational inclinations have been measured using asteroseismology. We supplement our sample with one binary whose visual orbit has been determined using speckle interferometry and present the projected spin-orbit alignments in five systems. We find that each system, and the overall sampl…
We describe three useful applications of asteroseismology in the context of exoplanet science: (1) the detailed characterisation of exoplanet host stars; (2) the measurement of stellar inclinations; and (3) the determination of orbital eccentricity from transit duration making use of asteroseismic stellar densities. We do so using the example system Kepler-410 (Van Eylen et al. 2014). This is one of the brightest (V = 9.4) Kepler exoplanet host stars, containing a small (2.8 Rearth) transiting planet in a long orbit (17.8 days), and one or more additional non-transiting planets as indicated by…
Observed transit timing variation (TTV) potentially reveals the period decay caused by star-planet tidal interaction which can explain the orbital migration of hot Jupiters. We report the TTV of XO-3b, using TESS observed timings and archival timings. We generate a photometric pipeline to produce light curves from raw TESS images and find the difference between our pipeline and TESS PDC is negligible for timing analysis. TESS timing presents a shift of 17.6 minutes (80 $σ$), earlier than the prediction from the previous ephemeris. The best linear fit for all timings available gives a Bayesian …
We present the first homogeneous catalog of $Kepler$, $K2$, and $TESS$ host stars and the corresponding catalog of exoplanet properties, which contain 7993 stars and 9324 planets, respectively. We used isochrone fitting and $Gaia$ DR3 photometry, parallaxes, and spectrophotometric metallicities to compute precise, homogeneous $T_{\mathrm{eff}}$, $\log g$, masses, radii, mean stellar densities, luminosities, ages, distances, and V-band extinctions for 3248, 565, and 4180 $Kepler$, $K2$, and $TESS$ stars, respectively. We compared our stellar properties to studies using fundamental and precise c…
We present the discovery of TOI-197.01, the first transiting planet identified by the Transiting Exoplanet Survey Satellite (TESS) for which asteroseismology of the host star is possible. TOI-197 (HIP116158) is a bright (V=8.2 mag), spectroscopically classified subgiant which oscillates with an average frequency of about 430 muHz and displays a clear signature of mixed modes. The oscillation amplitude confirms that the redder TESS bandpass compared to Kepler has a small effect on the oscillations, supporting the expected yield of thousands of solar-like oscillators with TESS 2-minute cadence o…
We present and analyze 58 transit light curves of TrES-3b and 98 transit light curves of Qatar-1b observed by Transiting Exoplanet Survey Satellite (TESS), plus two transit light curves of Qatar-1b observed by us using a ground-based 1.23\,m telescope. These light curves are combined with the best-quality light curves taken from the Exoplanet Transit Database (ETD) and literature. The precisely determined mid-transit times from these light curves enable us to obtain the refined orbital ephemerides with improved precision for both hot Jupiters. From the timing analysis, we find an indication fo…
The study of fundamental properties (such as temperatures, radii, masses, and ages) and interior processes (such as convection and angular momentum transport) of stars has implications on various topics in astrophysics, ranging from the evolution of galaxies to understanding exoplanets. In this contribution I will review the basic principles of two key observational methods for constraining fundamental and interior properties of single field stars: the study stellar oscillations (asteroseismology) and optical long-baseline interferometry. I will highlight recent breakthrough discoveries in ast…
The Transiting Exoplanet Survey Satellite (TESS) mission has provided photometric light curves for stars across nearly the entire sky. This allows for the application of asteroseismology to a pool of potential solar-like oscillators that is unprecedented in size. We aim to produce a catalogue of solar-like oscillators observed by TESS in the 120-second and 20-second cadence modes. The catalogue is intended to highlight stars oscillating at frequencies above the TESS 30-minute cadence Nyquist frequency with the purpose of encompassing the main sequence and subgiant evolutionary phases. We aim t…
We confirm the Kepler planet candidate Kepler-410b (KOI-42b) as a Neptune sized exoplanet on a 17.8 day, eccentric orbit around the bright (Kp = 9.4) star Kepler-410A. This is the third brightest confirmed planet host star in the Kepler field and one of the brightest hosts of all currently known transiting exoplanets. Kepler-410 consists of a blend between the fast rotating planet host star (Kepler-410A) and a fainter star (Kepler-410B), which has complicated the confirmation of the planetary candidate. Employing asteroseismology, using constraints from the transit light curve, adaptive optics…
We report the discovery in $TESS$ Sectors 3 and 4 of a compact triply eclipsing triple star system. TIC 209409435 is a previously unknown eclipsing binary with a period of 5.717 days, and the presence of a third star in an outer eccentric orbit of 121.872 day period was found from two sets of third-body eclipses and from eclipse timing variations. The latter exhibit signatures of strong 3rd-body perturbations. After the discovery, we obtained follow-up ground-based photometric observations of several binary eclipses as well as another of the third-body eclipses. We carried out comprehensive an…
The Kwee - van Woerden (KvW) method used for the determination of eclipse minimum times has been a staple in eclipsing binary research for decades, due its simplicity and the independence of external input parameters, which also makes it well-suited to obtaining timings of exoplanet transits. However, its estimates of the timing error have been known to have a low reliability. During the analysis of very precise photometry of CM Draconis eclipses from TESS space mission data, KvW's original equation for the timing error estimate produced numerical errors, which evidenced a fundamental problem …
Homogeneous stellar parameters for 717,807 TESS FGK stars using Gaia DR3
Mullard Space Science Laboratory, University College London（穆拉德空间科学实验室，伦敦大学学院）；Sydney Institute for Astronomy, School of Physics, University of Sydney（悉尼天文研究所，物理学院，悉尼大学）
AU Mic is a young planetary system with a resolved debris disc showing signs of planet formation and two transiting warm Neptunes near mean-motion resonances. Here we analyse three transits of AU Mic b observed with the CHaracterising ExOPlanet Satellite (CHEOPS), supplemented with sector 1 and 27 Transiting Exoplanet Survey Satellite (TESS) photometry, and the All-Sky Automated Survey (ASAS) from the ground. The refined orbital period of AU Mic b is 8.462995 \pm 0.000003 d, whereas the stellar rotational period is P_{rot}=4.8367 \pm 0.0006 d. The two periods indicate a 7:4 spin--orbit commens…
Identifying long-period eclipsing binaries with space-based photometry is still a challenge even in the century of space telescopes due to the relatively short observation sequences and short lifetime of these missions. The Transiting Exoplanet Survey Satellite (TESS) space telescope is an appropriate tool to supplement previous space-based observations. In this paper we report the first results of the eclipse timing variation (ETV) analyses of eclipsing binaries (EBs) measured by CoRoT and TESS space telescopes. Among the 1428 EB candidates we found 4 new potential triple candidates, for whic…
Driven largely by multiple ground-based radial-velocity (RV) surveys and photometric space missions such as Kepler and K2, the discovery of new exoplanets has increased rapidly since the early 2000s. However, due to a target selection bias in favor of main-sequence stars, only a handful of transiting planets have been found orbiting evolved hosts. These planets, most of which are giants, hold important information regarding the formation and evolution of planetary systems. In this thesis, I sought to increase the sample of known giant planets orbiting red-giant stars, focusing on data from NAS…
We investigate whether there is a variation in the orbital period of the short-period brown dwarf-mass KELT-1\,b, which is one of the best candidates to observe orbital decay. We obtain 19 high-precision transit light curves of the target using six different telescopes. We add all precise and complete transit light curves from open databases and the literature, as well as the available TESS observations from sectors 17 and 57, to form a transit timing variation (TTV) diagram spanning more than 10 years of observations. The analysis of the TTV diagram, however, is inconclusive in terms of a sec…
We examine the ability of the Transiting Exoplanet Survey Satellite (TESS) to detect and improve our understanding of planetary systems in the Kepler field. By modeling the expected transits of all confirmed and candidate planets detected by Kepler as expected to be observed by TESS, we find that TESS has a greater than 50% chance of detecting 260 of these planets at the 3 sigma level in one sector of observations and an additional 120 planets in two sectors. Most of these are large planets in short orbits around their host stars, although a small number of rocky planets are expected to be rec…
We report the discovery and complex analyses of the first two compact hierarchical triple star systems discovered with TESS in or near its southern continuous viewing zone during Year 1. Both TICs 167692429 and 220397947 were previously unknown eclipsing binaries, and the presence of a third companion star was inferred from eclipse timing variations exhibiting signatures of strong 3rd-body perturbations and, in the first system, also from eclipse depth variations. We carried out comprehensive analyses, including the simultaneous photodynamical modelling of TESS and archival ground-based WASP l…
TESS Pulsation Timing Reveals the JWST Calibration Star HD 158485 as a Double-pulsator Binary
Xinjiang Astronomical Observatory, Chinese Academy of Sciences（中国科学院新疆天文台）；Instituto de Astrofísica de Andalucía - CSIC（安达卢西亚天体物理研究所-西班牙国家研究委员会）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文与空间科学学院）；Chinese Academy of Sciences South America Center for Astronomy（中国科学院南美天文中心）
本研究通过 TESS 脉冲计时，发现 JWST 校准星 HD 158485 为双脉冲星双星，测得其轨道参数，盲预测验证了轨道可靠性，还发现未分辨伴星会影响分光光度预测。
HATS-18b is a transiting planet with a large mass and a short orbital period, and is one of the best candidates for the detection of orbital decay induced by tidal effects. We present extensive photometry of HATS-18 from which we measure 27 times of mid-transit. Two further transit times were measured from data from the Transiting Exoplanet Survey Satellite (TESS) and three more taken from the literature. The transit timings were fitted with linear and quadratic ephemerides and an upper limit on orbital decay was determined. This corresponds to a lower limit on the modified stellar tidal quali…
Giant stars as known exoplanet hosts are relatively rare due to the potential challenges in acquiring precision radial velocities and the small predicted transit depths. However, these giant host stars are also some of the brightest in the sky and so enable high signal-to-noise follow-up measurements. Here we report on new observations of the bright (V ~ 3.3) giant star $ι$ Draconis ($ι$ Dra), known to host a planet in a highly eccentric ~511 day period orbit. TESS observations of the star over 137 days reveal asteroseismic signatures, allowing us to constrain the stellar radius, mass, and age…
Luminaries in the Sky: The TESS Legacy Sample of Bright Stars. I. Asteroseismic detections in naked-eye main-sequence and sub-giant solar-like oscillators
High-precision transit photometry supplies ideal opportunities for detecting new exoplanets and characterizing their physical properties, which usually encode valuable information for unveiling the planetary structure, atmosphere and dynamical history. We present revised properties of three transiting systems (i.e., HAT-P-13, HAT-P-16 and WASP-32) through analyzing TESS photometry and ground-based transit observations, which were obtained at the 1m and 2.4m telescopes of Yunnan Observatories, China, and the 1.2m telescope of Hamburg Observatory, Germany, as well as the data in the literature. …
WASP-12 b, WASP-33 b, WASP-36 b, and WASP-46 b are four transiting planetary systems which we have studied. These systems' light curves were derived from observations made by the Transiting Light Exoplanet Survey Satellite (TESS) and some ground-based telescopes. We used Exofast-v1 to model these light curves and calculate mid-transit times. Also, we plotted TTV diagrams for them using derived mid-transit times and those available within the literature. O-C analysis of these timings enables us to refine the linear ephemeris of four systems. We measured WASP-12's tidal quality factor based on a…
The TESS-Keck Survey XVII: Precise Mass Measurements in a Young, High Multiplicity Transiting Planet System using Radial Velocities and Transit Timing Variations
