- ID:
- ivo://CDS.VizieR/J/AJ/151/117
- Title:
- R photometry of (225088) 2007 OR_10_
- Short Name:
- J/AJ/151/117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first comprehensive thermal and rotational analysis of the second most distant trans-Neptunian object (TNOs) (225088)2007OR_10_. We combined optical light curves provided by the Kepler Space Telescope-K2 extended mission and thermal infrared data provided by the Herschel Space Observatory. We found that (225088)2007OR_10_ is likely to be larger and darker than derived by earlier studies: we obtained a diameter of d=1535_-225_^+75^km which places (225088) 2007OR_10_ in the biggest top three TNOs. The corresponding visual geometric albedo is p_V_=0.089_-0.009_^+0.031^. The light-curve analysis revealed a slow rotation rate of P_rot_=44.81+/-0.37hr, superseded by very few objects. The most likely light-curve solution is double-peaked with a slight asymmetry; however, we cannot safely rule out the possibility of having a rotation period of P_rot_=22.40+/-0.18hr, which corresponds to a single-peaked solution. Due to the size and slow rotation, the shape of the object should be a MacLaurin ellipsoid, so the light variation should be caused by surface inhomogeneities. Its newly derived larger diameter also implies larger surface gravity and a more likely retention of volatiles--CH_4_, CO, and N_2_--on the surface.
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- ID:
- ivo://CDS.VizieR/J/AJ/152/127
- Title:
- Sloan i follow-up light curves of HATS-18
- Short Name:
- J/AJ/152/127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by the HATSouth network of HATS-18b: a 1.980+/-0.077M_J_, 1.337_-0.049_^+0.102^R_J_ planet in a 0.8378day orbit, around a solar analog star (mass 1.037+/-0.047M_{Sun}_ and radius 1.020_-0.031_^+0.057^R_{Sun}_) with V=14.067+/-0.040mag. The high planet mass, combined with its short orbital period, implies strong tidal coupling between the planetary orbit and the star. In fact, given its inferred age, HATS-18 shows evidence of significant tidal spin up, which together with WASP-19 (a very similar system) allows us to constrain the tidal quality factor for Sun-like stars to be in the range of 6.5<~log_10_(Q^*^/k_2_)<~7 even after allowing for extremely pessimistic model uncertainties. In addition, the HATS-18 system is among the best systems (and often the best system) for testing a multitude of star-planet interactions, be they gravitational, magnetic, or radiative, as well as planet formation and migration theories.
- ID:
- ivo://CDS.VizieR/J/ApJ/691/1145
- Title:
- Spectrophotometry of TrES-3 and TrES-4
- Short Name:
- J/ApJ/691/1145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report new spectroscopic and photometric observations of the parent stars of the recently discovered transiting planets TrES-3 and TrES-4. A detailed abundance analysis based on high-resolution spectra yields [Fe/H]=-0.19+/-0.08, Teff=5650+/-75K, and logg=4.4+/-0.1 for TrES-3, and [Fe/H]=+0.14+/-0.09, Teff=6200+/-75K, and logg=4.0+/-0.1 for TrES-4. The accuracy of the effective temperatures is supported by a number of independent consistency checks. The spectroscopic orbital solution for TrES-3 is improved with our new radial velocity measurements of that system, as are the light-curve parameters for both systems based on newly acquired photometry for TrES-3 and a reanalysis of existing photometry for TrES-4. With these revised stellar parameters, we obtain improved values for the planetary masses and radii. We find M_p_=1.910^+0.075^_-0.080_M_Jup_, R_p_=1.336^+0.031^_-0.036_R_Jup_ for TrES-3, and M_p_=0.925+/-0.082M_Jup_, R_p_=1.783^+0.093^_-0.086_R_Jup_ for TrES-4. We confirm TrES-4 as the planet with the largest radius among the currently known transiting hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/AJ/152/142
- Title:
- Spitzer and WISE light curves of Neptune
- Short Name:
- J/AJ/152/142
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Spitzer Space Telescope in 2016 February to obtain high cadence, high signal-to-noise, 17hr duration light curves of Neptune at 3.6 and 4.5{mu}m. The light curve duration was chosen to correspond to the rotation period of Neptune. Both light curves are slowly varying with time, with full amplitudes of 1.1mag at 3.6{mu}m and 0.6mag at 4.5{mu}m. We have also extracted sparsely sampled 18hr light curves of Neptune at W1 (3.4{mu}m) and W2 (4.6{mu}m) from the Wide-feld Infrared Survey Explorer (WISE)/NEOWISE archive at six epochs in 2010-2015. These light curves all show similar shapes and amplitudes compared to the Spitzer light curves but with considerable variation from epoch to epoch. These amplitudes are much larger than those observed with Kepler/K2 in the visible (amplitude ~0.02mag) or at 845nm with the Hubble Space Telescope (HST) in 2015 and at 763nm in 2016 (amplitude ~0.2mag). We interpret the Spitzer and WISE light curves as arising entirely from reflected solar photons, from higher levels in Neptune's atmosphere than for K2. Methane gas is the dominant opacity source in Neptune's atmosphere, and methane absorption bands are present in the HST 763 and 845nm, WISE W1, and Spitzer 3.6{mu}m filters.
- ID:
- ivo://CDS.VizieR/J/ApJ/755/9
- Title:
- Spitzer/IRAC light curves of GJ 436 system
- Short Name:
- J/ApJ/755/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the detection of UCF-1.01, a strong exoplanet candidate with a radius 0.66+/-0.04 times that of Earth (R_{oplus}_). This sub-Earth sized planet transits the nearby M-dwarf star GJ 436 with a period of 1.365862+/-8x10^-6^ days. We also report evidence of a 0.65+/-0.06R_{Earth}_ exoplanet candidate (labeled UCF-1.02) orbiting the same star with an undetermined period. Using the Spitzer Space Telescope, we measure the dimming of light as the planets pass in front of their parent star to assess their sizes and orbital parameters. If confirmed today, UCF-1.01 and UCF-1.02 would be designated GJ 436c and GJ 436d, respectively, and would be part of the first multiple-transiting-planet system outside of the Kepler field. Assuming Earth-like densities of 5.515g/cm3, we predict both candidates to have similar masses (~0.28M_{oplus}_, 2.6 Mars-masses) and surface gravities of ~0.65g (where g is the gravity on Earth). UCF-1.01's equilibrium temperature (T_eq_, where emitted and absorbed radiation balance for an equivalent blackbody) is 860K, making the planet unlikely to harbor life as on Earth. Its weak gravitational field and close proximity to its host star imply that UCF-1.01 is unlikely to have retained its original atmosphere; however, a transient atmosphere is possible if recent impacts or tidal heating were to supply volatiles to the surface. We also present additional observations of GJ 436b during secondary eclipse. The 3.6{mu}m light curve shows indications of stellar activity, making a reliable secondary eclipse measurement impossible. A second non-detection at 4.5{mu}m supports our previous work in which we find a methane-deficient and carbon monoxide-rich dayside atmosphere.
- ID:
- ivo://CDS.VizieR/J/AJ/141/11
- Title:
- Spitzer observations of planet-host stars
- Short Name:
- J/AJ/141/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since giant planets scatter planetesimals within a few tidal radii of their orbits, the locations of existing planetesimal belts indicate regions where giant planet formation failed in bygone protostellar disks. Infrared observations of circumstellar dust produced by colliding planetesimals are therefore powerful probes of the formation histories of known planets. Here we present new Spitzer infrared spectrograph (IRS) spectrophotometry of 111 solar-type stars, including 105 planet hosts. Our observations reveal 11 debris disks, including two previously undetected debris disks orbiting HD 108874 and HD 130322. Combining the 32um spectrophotometry with previously published MIPS photometry, we find that the majority of debris disks around solar-type stars have temperatures in the range 60<~T_dust_<~100K. Assuming a dust temperature T_dust_=70K, which is representative of the nine debris disks detected by both IRS and MIPS, debris rings surrounding Sun-like stars orbit between 15 and 240AU depending on the mean particle size. Our observations imply that the planets detected by radial-velocity searches formed within 240AU of their parent stars. If any of the debris disks studied here have mostly large, blackbody emitting grains, their companion giant planets must have formed in a narrow region between the ice line and 15AU.
- ID:
- ivo://CDS.VizieR/J/A+A/471/L51
- Title:
- Spitzer observations of the hot Neptune GJ 436b
- Short Name:
- J/A+A/471/L51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Spitzer Space Telescope infrared photometry of a primary transit of the hot Neptune GJ 436b. The observations were obtained using the 8{mu}m band of the InfraRed Array Camera (IRAC).
- ID:
- ivo://CDS.VizieR/J/ApJ/786/2
- Title:
- Spitzer photometric time series of HD 97658
- Short Name:
- J/ApJ/786/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Super-Earths transiting nearby bright stars are key objects that simultaneously allow for accurate measurements of both their mass and radius, providing essential constraints on their internal composition. We present here the confirmation, based on Spitzer transit observations, that the super-Earth HD 97658 b transits its host star. HD 97658 is a low-mass (M_*_=0.77+/-0.05 M_{sun}_) K1 dwarf, as determined from the Hipparcos parallax and stellar evolution modeling. To constrain the planet parameters, we carry out Bayesian global analyses of Keck-High Resolution Echelle Spectrometer (Keck-HIRES) radial velocities and Microvariability and Oscillations of STars (MOST) and Spitzer photometry. HD 97658 b is a massive (M_p_=7.55_-0.79_^+0.83^ M_{earth}_) and large (R_p_=2.247_0.095_^+0.098^ R_{earth}_ at 4.5 {mu}m) super-Earth. We investigate the possible internal compositions for HD 97658 b. Our results indicate a large rocky component, of at least 60% by mass, and very little H-He components, at most 2% by mass. We also discuss how future asteroseismic observations can improve the knowledge of the HD 97658 system, in particular by constraining its age. Orbiting a bright host star, HD 97658 b will be a key target for upcoming space missions such as the Transiting Exoplanet Survey Satellite (TESS), the Characterizing Exoplanet Satellite (CHEOPS), the Planetary Transits and Oscillations of stars (PLATO), and the James Webb Space Telescope to characterize thoroughly its structure and atmosphere.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A117
- Title:
- Spitzer search for 19 planets
- Short Name:
- J/A+A/601/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Short-period super-Earths and Neptunes are now known to be very frequent around solar-type stars. Improving our understanding of these mysterious planets requires the detection of a significant sample of objects suitable for detailed characterization. Searching for the transits of the low-mass planets detected by Doppler surveys is a straightforward way to achieve this goal. Indeed, Doppler surveys target the most nearby main-sequence stars, they regularly detect close-in low-mass planets with significant transit probability, and their radial velocity data constrain strongly the ephemeris of possible transits. In this context, we initiated in 2010 an ambitious Spitzer multi-Cycle transit search project that targeted 25 low-mass planets detected by radial velocity, focusing mainly on the shortest-period planets detected by the HARPS spectrograph. We report here null results for 19 targets of the project. For 16 planets out of 19, a transiting configuration is strongly disfavored or firmly rejected by our data for most planetary compositions.We derive a posterior probability of 83% that none of the probed 19 planets transits (for a prior probability of 22%), which still leaves a significant probability of 17% that at least one of them does transit. Globally, our Spitzer project revealed or confirmed transits for three of its 25 targeted planets, and discarded or disfavored the transiting nature of 20 of them. Our light curves demonstrate for Warm Spitzer excellent photometric precisions: for 14 targets out of 19, we were able to reach standard deviations that were better than 50ppm per 30 min intervals. Combined with its Earth-trailing orbit, which makes it capable of pointing any star in the sky and to monitor it continuously for days, this work confirms Spitzer as an optimal instrument to detect sub-mmag-deep transits on the bright nearby stars targeted by Doppler surveys.
- ID:
- ivo://CDS.VizieR/J/ApJ/809/25
- Title:
- Stellar and planet properties for K2 candidates
- Short Name:
- J/ApJ/809/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The extended Kepler mission, K2, is now providing photometry of new fields every three months in a search for transiting planets. In a recent study, Foreman-Mackey and collaborators presented a list of 36 planet candidates orbiting 31 stars in K2 Campaign 1. In this contribution, we present stellar and planetary properties for all systems. We combine ground-based seeing-limited survey data and adaptive optics imaging with an automated transit analysis scheme to validate 21 candidates as planets, 17 for the first time, and identify 6 candidates as likely false positives. Of particular interest is K2-18 (EPIC 201912552), a bright (K=8.9) M2.8 dwarf hosting a 2.23+/-0.25 R_{earth}_ planet with T_eq_=272+/-15 K and an orbital period of 33 days. We also present two new open-source software packages which enable this analysis. The first, isochrones, is a flexible tool for fitting theoretical stellar models to observational data to determine stellar properties using a nested sampling scheme to capture the multimodal nature of the posterior distributions of the physical parameters of stars that may plausibly be evolved. The second is vespa, a new general-purpose procedure to calculate false positive probabilities and statistically validate transiting exoplanets.