- 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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- ID:
- ivo://CDS.VizieR/J/AJ/161/65
- Title:
- THYME. IV. 3 Exoplanets around TOI-451 B
- Short Name:
- J/AJ/161/65
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Young exoplanets can offer insight into the evolution of planetary atmospheres, compositions, and architectures. We present the discovery of the young planetary system TOI-451 (TIC257605131, GaiaDR24844691297067063424). TOI-451 is a member of the 120Myr old Pisces-Eridanus stream (Psc-Eri). We confirm membership in the stream with its kinematics, its lithium abundance, and the rotation and UV excesses of both TOI451 and its wide-binary companion, TOI-451B (itself likely an M-dwarf binary). We identified three candidate planets transiting in the Transiting Exoplanet Survey Satellite data and followed up the signals with photometry from Spitzer and ground-based telescopes. The system comprises three validated planets at periods of 1.9, 9.2, and 16days, with radii of 1.9, 3.1, and 4.1 R, respectively. The host star is near-solar mass with V=11.0 and H=9.3 and displays an infrared excess indicative of a debris disk. The planets offer excellent prospects for transmission spectroscopy with the Hubble Space Telescope and the James Webb Space Telescope, providing the opportunity to study planetary atmospheres that may still be in the process of evolving.
- ID:
- ivo://CDS.VizieR/J/ApJ/891/58
- Title:
- TIC star exposure times for JWST, LUVOIR and OST
- Short Name:
- J/ApJ/891/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The search for water-rich Earth-sized exoplanets around low-mass stars is rapidly gaining attention because they represent the best opportunity to characterize habitable planets in the near future. Understanding the atmospheres of these planets and determining the optimal strategy for characterizing them through transmission spectroscopy with our upcoming instrumentation is essential in order to constrain their environments. For this study, we present simulated transmission spectra of tidally locked Earth-sized ocean-covered planets around late-M to mid-K stellar spectral types, utilizing the results of general circulation models previously published by Kopparapu+ (2017ApJ...845....5K) as inputs for our radiative transfer calculations performed using NASA's Planetary Spectrum Generator (psg.gsfc.nasa.gov). We identify trends in the depth of H2O spectral features as a function of planet surface temperature and rotation rate. These trends allow us to calculate the exposure times necessary to detect water vapor in the atmospheres of aquaplanets through transmission spectroscopy with the upcoming James Webb Space Telescope (JWST) as well as several future flagship space telescope concepts under consideration (the Large UV Optical Infrared Surveyor (LUVOIR) and the Origins Space Telescope (OST)) for a target list constructed from the Transiting Exoplanet Survey Satellite (TESS) Input Catalog (TIC). Our calculations reveal that transmission spectra for water-rich Earth-sized planets around low-mass stars will be dominated by clouds, with spectral features <20ppm, and only a small subset of TIC stars would allow for the characterization of an ocean planet in the habitable zone. We thus present a careful prioritization of targets that are most amenable to follow-up characterizations with next-generation instrumentation, in order to assist the community in efficiently utilizing precious telescope time.
- ID:
- ivo://CDS.VizieR/J/AJ/162/114
- Title:
- Times & durations in Kepler-80 planetary system
- Short Name:
- J/AJ/162/114
- Date:
- 16 Mar 2022 00:10:21
- Publisher:
- CDS
- Description:
- Since the launch of the Kepler space telescope in 2009 and the subsequent K2 mission, hundreds of multiplanet systems have been discovered. The study of such systems, both as individual systems and as a population, leads to a better understanding of planetary formation and evolution. Kepler-80, a K dwarf hosting six super-Earths, was the first system known to have four planets in a chain of resonances, a repeated geometric configuration. Transiting planets in resonant chains can enable us to estimate not only the planets' orbits and sizes but also their masses. Since the original resonance analysis and TTV fitting of Kepler-80, a new planet has been discovered whose signal likely altered the measured masses of the other planets. Here, we determine masses and orbits for all six planets hosted by Kepler-80 by direct forward photodynamical modeling of the light curve of this system. We then explore the resonant behavior of the system. We find that the four middle planets are in a resonant chain, but that the outermost planet only dynamically interacts in ~14% of our solutions. We also find that the system and its dynamic behavior are consistent with in situ formation and compare our results to two other resonant chain systems, Kepler-60 and TRAPPIST-1.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A145
- Title:
- TOI-269 b light curves
- Short Name:
- J/A+A/650/A145
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the confirmation of a new sub-Neptune close to the transition between Super-Earths and sub-Neptunes transiting the M2 dwarf TOI-269. The exoplanet candidate is identified in multiple TESS sectors and is validated with high-precision spectroscopy from HARPS and ground-based photometric follow-up from ExTrA and LCO-CTIO. We determine mass, radius and bulk density of the exoplanet by jointly modeling both photometry and radial velocities with juliet. The transiting exoplanet has an orbital period of P=3.7 days, a radius of 2.77+/-0.12R_{Earth}_, and a mass of 8.8+/-1.4M_{Earth}_. Since TOI-269 b lies among the best targets of its category for atmospheric characterization, it would be interesting to probe the atmosphere of this exoplanet with transmission spectroscopy in order to compare it to other sub-Neptunes. With an eccentricity e=0.425^+0.082^_-0.086_, TOI-269 b has one of the highest eccentricity among exoplanets with periods less than 10 days. The star being likely a few Gyr old, this system does not appear to be dynamically young. We surmise TOI-269 b may have acquired a high eccentricity as it migrated inward through planet-planet interactions.
- ID:
- ivo://CDS.VizieR/J/AJ/160/22
- Title:
- TOI-1235 Radial velocities & optical spectroscopy
- Short Name:
- J/AJ/160/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/nonrocky transition in period-radius space. Here we present the confirmation of TOI-1235b (P=3.44days, r_p_=1.738_-0.076_^+0.087^R_{Earth}_), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/nonrocky transition around early M dwarfs (R_s_=0.630{+/-}0.015R_{sun}_, M_s_=0.640{+/-}0.016M_{sun}_). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high- resolution imaging, and a set of 38 precise radial velocities (RVs) from HARPS-N and HIRES. We measure a planet mass of 6.91_-0.85_^+0.75^M_{Earth}_, which implies an iron core mass fraction of 20_-12_^+15^% in the absence of a gaseous envelope. The bulk composition of TOI-1235b is therefore consistent with being Earth-like, and we constrain an H/He envelope mass fraction to be <0.5% at 90% confidence. Our results are consistent with model predictions from thermally driven atmospheric mass loss but not with gas-poor formation, suggesting that the former class of processes remains efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin (P=21.8_-0.8_^+0.9^days, m_p_sini=13.0_-5.3_^+3.8^M_{Earth}_) that cannot be firmly ruled out by our data.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A124
- Title:
- TOI-1201 RV and activity index
- Short Name:
- J/A+A/656/A124
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the discovery of a transiting mini-Neptune around TOI-1201, a relatively bright and moderately young early M dwarf (J~9.5mag, ~600-800Myr) in an equal-mass ~8arcsecond-wide binary system, using data from the Transiting Exoplanet Survey Satellite (TESS), along with follow-up transit observations. With an orbital period of 2.49d, TOI-1201~b is a warm mini-Neptune with a radius of R_b_=2.415+/-0.090R_{Earth}_. This signal is also present in the precise radial velocity measurements from CARMENES, confirming the existence of the planet and providing a planetary mass of M_b_=6.28+/-0.88M_{Earth}_ and, thus, an estimated bulk density of 2.45^+0.48^_-0.42_g/cm^3^. The spectroscopic observations additionally show evidence of a signal with a period of 19d and a long periodic variation of undetermined origin. In combination with ground-based photometric monitoring from WASP-South and ASAS-SN, we attribute the 19d signal to the stellar rotation period (P_rot_=19-23d), although we cannot rule out that the variation seen in photometry belongs to the visually close binary companion. We calculate precise stellar parameters for both TOI-1201 and its companion. The transiting planet is an excellent target for atmosphere characterization (the transmission spectroscopy metric is 97^+21^_-16_) with the upcoming James Webb Space Telescope. It is also feasible to measure its spin-orbit alignment via the Rossiter-McLaughlin effect using current state-of-the-art spectrographs with submeter per second radial velocity precision.
- ID:
- ivo://CDS.VizieR/J/AJ/159/83
- Title:
- Transit analysis for the K2-25 system
- Short Name:
- J/AJ/159/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The abundance of planets with orbital periods of a few to tens of days suggests that exoplanets experience complex dynamical histories. Planets in young stellar clusters or associations have well-constrained ages and therefore provide an opportunity to explore the dynamical evolution of exoplanets. K2-25b is a Neptune-sized planet in an eccentric, 3.48day orbit around an M4.5 dwarf star in the Hyades cluster (650Myr). In order to investigate its non-zero eccentricity and tight orbit, we analyze transit timing variations (TTVs) which could reveal clues to the migration processes that may have acted on the planet. We obtain 12 nonconsecutive transits using the MEarth observatories and long-term photometric monitoring, which we combine with 10 transits from the Spitzer Space Telescope and 20 transits from K2. Tables of MEarth photometry accompany this work. We fit each transit lightcurve independently. We first investigate whether inhomogeneities on the stellar surface (such as spots or plages) are differentially affecting our transit observations. The measured transit depth does not vary significantly between transits, though we see some deviations from the fiducial transit model. We then looked for TTVs as evidence of a nontransiting perturber in the system. We find no evidence for >1M_{Earth}_ mass companions within a 2:1 period ratio, or for >5M_{Earth}_ mass planets within a 7:2 period ratio.
- ID:
- ivo://CDS.VizieR/J/AJ/161/72
- Title:
- 180 Transit and occultation times for WASP-12b
- Short Name:
- J/AJ/161/72
- Date:
- 10 Dec 2021
- Publisher:
- CDS
- Description:
- Theory suggests that the orbits of some close-in giant planets should decay due to tidal interactions with their host stars. To date, WASP-12b is the only hot Jupiter reported to have a decaying orbit, at a rate of 29{+/-}2ms/yr. We analyzed data from NASA's Transiting Exoplanet Survey Satellite (TESS) to verify that WASP-12b's orbit is indeed changing. We find that the TESS transit and occultation data are consistent with a decaying orbit with an updated period of 1.091420090{+/-}0.000000041days and a decay rate of 32.53{+/-}1.62ms/yr. We find an orbital decay timescale of {tau}=P/|P|=2.90{+/-}0.14Myr. If the observed decay results from tidal dissipation, the modified tidal quality factor is Q_*_'=1.39{+/-}0.15x10^5^, which falls at the lower end of values derived for binary star systems and hot Jupiters. Our result highlights the power of space-based photometry for investigating the orbital evolution of short-period exoplanets.
- ID:
- ivo://CDS.VizieR/J/AJ/161/174
- Title:
- Transit depth biases & error bars for 31 planets
- Short Name:
- J/AJ/161/174
- Date:
- 20 Jan 2022
- Publisher:
- CDS
- Description:
- The occurrence of a planet transiting in front of its host star offers the opportunity to observe the planet's atmosphere filtering starlight. The fraction of occulted stellar flux is roughly proportional to the optically thick area of the planet, the extent of which depends on the opacity of the planet's gaseous envelope at the observed wavelengths. Chemical species, haze, and clouds are now routinely detected in exoplanet atmospheres through rather small features in transmission spectra, i.e., collections of planet-to-star area ratios across multiple spectral bins and/or photometric bands. Technological advances have led to a shrinking of the error bars down to a few tens of parts per million (ppm) per spectral point for the brightest targets. The upcoming James Webb Space Telescope (JWST) is anticipated to deliver transmission spectra with precision down to 10ppm. The increasing precision of measurements requires a reassessment of the approximations hitherto adopted in astrophysical models, including transit light-curve models. Recently, it has been shown that neglecting the planet's thermal emission can introduce significant biases in the transit depth measured with the JWST/Mid-InfraRed Instrument, integrated between 5 and 12{mu}m. In this paper, we take a step forward by analyzing the effects of the approximation on transmission spectra over the 0.6-12{mu}m wavelength range covered by various JWST instruments. We present open-source software to predict the spectral bias, showing that, if not corrected, it may affect the inferred molecular abundances and thermal structure of some exoplanet atmospheres.
