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22071. The Swan: an approach to derive surface gravity
ID:
ivo://CDS.VizieR/J/AJ/161/170
Title:
The Swan: an approach to derive surface gravity
Short Name:
J/AJ/161/170
Date:
20 Jan 2022
Publisher:
CDS
Description:
Stellar light curves are well known to encode physical stellar properties. Precise, automated, and computationally inexpensive methods to derive physical parameters from light curves are needed to cope with the large influx of these data from space-based missions such as Kepler and TESS. Here we present a new methodology that we call "The Swan", a fast, generalizable, and effective approach for deriving stellar surface gravity (logg) for main-sequence, subgiant, and red giant stars from Kepler light curves using local linear regression on the full frequency content of Kepler long-cadence power spectra. With this inexpensive data-driven approach, we recover logg to a precision of ~0.02dex for 13822 stars with seismic logg values between 0.2 and 4.4dex and ~0.11dex for 4646 stars with Gaia-derived logg values between 2.3 and 4.6dex. We further develop a signal-to-noise metric and find that granulation is difficult to detect in many cool main-sequence stars (Teff<~5500K), in particular K dwarfs. By combining our logg measurements with Gaia radii, we derive empirical masses for 4646 subgiant and main-sequence stars with a median precision of ~7%. Finally, we demonstrate that our method can be used to recover logg to a similar mean absolute deviation precision for a TESS baseline of 27days. Our methodology can be readily applied to photometric time series observations to infer stellar surface gravities to high precision across evolutionary states.
22072. The Swift/BAT hard X-ray transient monitor
ID:
ivo://CDS.VizieR/J/ApJS/209/14
Title:
The Swift/BAT hard X-ray transient monitor
Short Name:
J/ApJS/209/14
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Swift/Burst Alert Telescope (BAT) hard X-ray transient monitor provides near real-time coverage of the X-ray sky in the energy range 15-50 keV. The BAT observes 88% of the sky each day with a detection sensitivity of 5.3 mCrab for a full-day observation and a time resolution as fine as 64s. The three main purposes of the monitor are (1) the discovery of new transient X-ray sources, (2) the detection of outbursts or other changes in the flux of known X-ray sources, and (3) the generation of light curves of more than 900 sources spanning over eight years. The primary interface for the BAT transient monitor is a public Web site. Between 2005 February 12 and 2013 April 30, 245 sources have been detected in the monitor, 146 of them persistent and 99 detected only in outburst. Among these sources, 17 were previously unknown and were discovered in the transient monitor. In this paper, we discuss the methodology and the data processing and filtering for the BAT transient monitor and review its sensitivity and exposure. We provide a summary of the source detections and classify them according to the variability of their light curves. Finally, we review all new BAT monitor discoveries. For the new sources that are previously unpublished, we present basic data analysis and interpretations.
22073. The SWIRE Data Service
ID:
ivo://jvo/swire
Title:
The SWIRE Data Service
Short Name:
SWIRE
Date:
05 Oct 2019 08:47:54
Publisher:
JVO
Description:
The Spitzer Wide-area InfraRed Extragalactic survey is one of six very large programs undertaken as Legacy surveys during the first year of the Spitzer Space Observatory. SWIRE has imaged nearly 50 square degrees (equal to the area of 250 full moons) divided among 6 different directions on the sky, detecting over 2 million galaxies by their heat radiation, some of them over 11 billion light years away.
22074. theta Cep radial velocity curve
ID:
ivo://CDS.VizieR/J/AN/341/989
Title:
theta Cep radial velocity curve
Short Name:
J/AN/341/989
Date:
21 Oct 2021
Publisher:
CDS
Description:
In 2015 a radial velocity monitoring campaign was started in order to redetermine and/or constrain the orbital solutions of spectroscopic binary systems. The observations were carried out at the University Observatory Jena with the echelle spectrograph FLECHAS. The results from the main part of our target sample are already published. For the final target of this campaign, theta Cep, we can now present an orbital solution based on a homogeneously covered radial velocity curve. The period of this single-lined spectroscopic binary turns out to be significantly larger and the orbit is much more eccentric compared to the given values in the 9th Catalogue of Spectroscopic Binary Orbits (Pourbaix et al., Cat. B/sb9).
22075. theta Cyg radial velocity variations
ID:
ivo://CDS.VizieR/J/A+A/506/1469
Title:
theta Cyg radial velocity variations
Short Name:
J/A+A/506/1469
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the frame of the search for extrasolar planets and brown dwarfs around early-type main-sequence stars, we present the results obtained on the early F-type star theta Cygni. ELODIE and SOPHIE at Observatoire de Haute-Provence (OHP) were used to obtain 91 and 162 spectra, respectively. Our dedicated radial-velocity measurement method was used to monitor the star's radial velocities over five years. We also use complementary, high angular resolution and high-contrast images taken with PUEO at CFHT. We show that theta Cygni radial velocities are quasi-periodically variable, with a ~150-day period. These variations are not due to the ~0.35M_{sun}_ stellar companion that we detected in imaging at more than 46AU from the star. The absence of correlation between the bisector velocity span variations and the radial velocity variations for this 7km/s vsini star, as well as other criteria indicate that the observed radial velocity variations are not due to stellar spots. The observed amplitude of the bisector velocity span variations also seems to rule out stellar pulsations. However, we observe a peak in the bisector velocity span periodogram at the same period as the one found in the radial velocity periodogram, which indicates a probable link between these radial velocity variations and the low amplitude lineshape variations which are of stellar origin. Long-period variations are not expected from this type of star to our knowledge. If a stellar origin (hence of new type) was to be confirmed for these long-period radial velocity variations, this would have several consequences on the search for planets around main-sequence stars, both in terms of observational strategy and data analysis. An alternative explanation for these variable radial velocities is the presence of at least one planet of a few Jupiter masses orbiting at less than 1AU; however this planet alone does not explain all observed features, and the theta Cygni system is obviously more complex than a planetary system with 1 or 2 planets. The available data do not allow to distinguish between these two possible origins. A vigourous follow-up in spectroscopy and photometry is needed to get a comprehensive view of the star intrinsic variability and/or its surrounding planetary system.
22076. The Taurus-Auriga ecosystem. I.
ID:
ivo://CDS.VizieR/J/ApJ/838/150
Title:
The Taurus-Auriga ecosystem. I.
Short Name:
J/ApJ/838/150
Date:
21 Oct 2021
Publisher:
CDS
Description:
The census of Taurus-Auriga has been assembled over seven decades and inherited the biases and incompleteness of the input studies. The unusual shape of its inferred initial mass function (IMF) and the existence of isolated disk-bearing stars suggest that additional (likely disk-free) members remain to be discovered. We therefore have begun a global reassessment of the census of Taurus-Auriga that exploits new data and better definitions of youth and kinematic membership. As a first step, we reconsider the membership of all disk-free candidate members from the literature with spectral type >=F0, 3h50min<{alpha}5h40min, and 14{deg}<{delta}<34{deg}. We combine data from the literature with Keck/HIRES and UH88/SNIFS spectra to test the membership of these candidates using the positions in the Hertzsprung-Russel diagram, proper motions, radial velocities, H{alpha}, lithium, and surface gravity. We find 218 confirmed or likely Taurus members, 160 confirmed or likely interlopers, and only 18 that lack sufficient evidence to draw firm conclusions. A significant fraction of these stars (81/218=37%) are not included in the most recent canonical member lists. There are few additional members to the immediate vicinity of the molecular clouds, preserving the IMFs that have been deemed anomalous in past work. Many of the likely Taurus members are instead distributed broadly across the search area. When combined with the known disk hosts, our updated census reveals two regimes: a high-density population with a high disk fraction (indicative of youth) that broadly traces the molecular clouds, and a low-density population with low disk fraction (hence likely older) that most likely represents previous generations of star formation.
22077. Theta Vir and 109 Vir uvby photometry
ID:
ivo://CDS.VizieR/J/A+AS/125/497
Title:
Theta Vir and 109 Vir uvby photometry
Short Name:
J/A+AS/125/497
Date:
21 Oct 2021
Publisher:
CDS
Description:
Differential Stroemgren uvby photometric observations from the Four College Automated Photoelectric Telescope are used to examine the possible variability of the spectrophotometric standards {theta} Vir and 109 Vir. No evidence is found for variability within a season of observation. Small year to year differences are most likely due to unaccounted for extinction changes.
22078. The TESS Habitable Zone Star Catalog
ID:
ivo://CDS.VizieR/J/ApJ/874/L8
Title:
The TESS Habitable Zone Star Catalog
Short Name:
J/ApJ/874/L8
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the Transiting Exoplanet Survey Satellite (TESS) Habitable Zone Stars Catalog, a list of 1822 nearby stars with a TESS magnitude brighter than T=12 and reliable distances from Gaia DR2, around which the NASA's TESS mission can detect transiting planets, which receive Earth-like irradiation. For all those stars TESS is sensitive down to 2 Earth radii transiting planets during one transit. For 408 stars TESS can detect such planets down to 1 Earth-size during one transit. For 1690 stars, TESS has the sensitivity to detect planets down to 1.6 times Earth-size, a commonly used limit for rocky planets in the literature, receiving Earth-analog irradiation. We select stars from the TESS Candidate Target List, based on TESS Input Catalog Version 7. We update their distances using Gaia Data Release 2, and determine whether the stars will be observed for long enough during the 2yr prime mission to probe their Earth-equivalent orbital distance for transiting planets. We discuss the subset of 227 stars for which TESS can probe the full extent of the Habitable Zone, the full region around a star out to about a Mars-equivalent orbit. Observing the TESS Habitable Zone Catalog Stars will also give us deeper insight into the occurrence rate of planets, out to Earth-analog irradiation as well as in the Habitable Zone, especially around cool stars. We present the stars by decreasing angular separation of the 1 au equivalent distance to provide insights into which stars to prioritize for ground-based follow-up observations with upcoming extremely large telescopes.
22079. The TESS Input Catalog and Candidate Target List
ID:
ivo://CDS.VizieR/J/AJ/156/102
Title:
The TESS Input Catalog and Candidate Target List
Short Name:
J/AJ/156/102
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Transiting Exoplanet Survey Satellite (TESS) will be conducting a nearly all-sky photometric survey over two years, with a core mission goal to discover small transiting exoplanets orbiting nearby bright stars. It will obtain 30 minute cadence observations of all objects in the TESS fields of view, along with two-minute cadence observations of 200000-400000 selected stars. The choice of which stars to observe at the two-minute cadence is driven by the need to detect small transiting planets, which leads to the selection of primarily bright, cool dwarfs. We describe the catalogs assembled and the algorithms used to populate the TESS Input Catalog (TIC), including plans to update the TIC with the incorporation of the Gaia second data release (Cat. I/345) in the near future. We also describe a ranking system for prioritizing stars according to the smallest transiting planet detectable, and assemble a Candidate Target List (CTL) using that ranking. We discuss additional factors that affect the ability to photometrically detect and dynamically confirm small planets, and we note additional stellar populations of interest that may be added to the final target list. The TIC is available on the STScI MAST server, and an enhanced CTL is available through the Filtergraph data visualization portal system at the URL http://filtergraph.vanderbilt.edu/tess_ctl.
22080. The TESS-Keck Survey. I. HD332231 Radial Velocities
ID:
ivo://CDS.VizieR/J/AJ/159/241
Title:
The TESS-Keck Survey. I. HD332231 Radial Velocities
Short Name:
J/AJ/159/241
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the detection of a Saturn-size exoplanet orbiting HD332231 (TOI1456) in light curves from the Transiting Exoplanet Survey Satellite (TESS). HD332231 an F8 dwarf star with a V-band magnitude of 8.56 was observed by TESS in Sectors 14 and 15. We detect a single-transit event in the Sector 15 presearch data conditioning (PDC) light curve. We obtain spectroscopic follow up observations of HD332231 with the Automated Planet Finder (APF), Keck I, and Spatial Observations Network Group (SONG) telescopes. The orbital period we infer from radial velocity (RV) observations leads to the discovery of another transit in Sector 14 that was masked by PDC due to scattered light contamination. A joint analysis of the transit and RV data confirms the planetary nature of HD332231b, a Saturn-size (0.867_-0.025_^+0.027^R_J_), sub-Saturn-mass (0.244{+/-}0.021M_J_) exoplanet on a 18.71day circular orbit. The low surface gravity of HD332231b and the relatively low stellar flux it receives make it a compelling target for transmission spectroscopy. Also, the stellar obliquity is likely measurable via the Rossiter-McLaughlin effect, an exciting prospect given the 0.14au orbital separation of HD332231b. The spectroscopic observations do not provide substantial evidence for any additional planets in the HD332231 system, but continued RV monitoring is needed to further characterize this system. We also predict that the frequency and duration of masked data in the PDC light curves for TESS Sectors 14-16 could hide transits of some exoplanets with orbital periods between 10.5 and 17.5days.

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