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22391. Transit light curves of HAT-P-12
ID:
ivo://CDS.VizieR/J/AJ/143/95
Title:
Transit light curves of HAT-P-12
Short Name:
J/AJ/143/95
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new photometric data of the transiting planet HAT-P-12b observed in 2011. Our three transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law. Including our measurements, 18 transit times spanning about 4.2yr were used to determine the improved ephemeris with a transit epoch of 2454187.85560+/-0.00011BJD and an orbital period of 3.21305961+/-0.00000035days. The physical properties of the star-planet system are computed using empirical calibrations from eclipsing binary stars and stellar evolutionary models, combined with both our transit parameters and previously known spectroscopic results. We found that the absolute dimensions of the host star are M_A_=0.73+/-0.02M{sun}, R_A_=0.70+/-0.01R_{sun}_, log g_A_=4.61+/-0.02, p_A_=2.10+/-0.09{rho}{sun}, and L_A_=0.21+/-0.01L_{sun}_. The planetary companion has M_b_=0.21+/-0.01M_{Jup}_, R_b_=0.94+/-0.01R_{Jup}_, log g_b_=2.77+/-0.02, {rho}_b_=0.24+/-0.01{rho}_{Jup}_, and T_eq_=960+/-14K. Our results agree well with standard models of irradiated gas giants with a core mass of 11.3M_{earth}_.
22392. Transit light curves of HAT-P-13b
ID:
ivo://CDS.VizieR/J/A+A/523/A84
Title:
Transit light curves of HAT-P-13b
Short Name:
J/A+A/523/A84
Date:
21 Oct 2021
Publisher:
CDS
Description:
A possible transit of HAT-P-13c has been predicted to occur on 2010 April 28. Here we report on the results of a multi-site campaign that has been organised to detect the event. CCD photometric observations have been carried out at five observatories in five countries. We reached 30% time coverage in a 5 days interval centered on the suspected transit of HAT-P-13c. Two transits of HAT-P-13b were also observed. No transit of HAT-P-13c has been detected while the campaign was on. By a numerical experiment with 10^5^ model systems we conclude that HAT-P-13c is not a transiting exoplanet with a significance level from 65% to 72%, depending on the planet parameters and the prior assumptions. We present two times of transit of HAT-P-13b ocurring at BJD 2455141.5522+/-0.0010 and BJD 2455249.4508+/-0.0020. The TTV of HAT-P-13b is consistent with zero within 0.001 days. The refined orbital period of HAT-P-13b is 2.916293+/-0.000010 days.
22393. Transit light curves of HD 189733
ID:
ivo://CDS.VizieR/J/AJ/133/1828
Title:
Transit light curves of HD 189733
Short Name:
J/AJ/133/1828
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry of HD 189733 during eight transits of its close-in giant planet, and out-of-transit photometry spanning 2yr. Using the transit photometry, we determine the stellar and planetary radii and the photometric ephemeris. Outside of transits, there are quasi-periodic flux variations with a 13.4-day period that we attribute to stellar rotation. In combination with previous results, we derive upper limits on the orbital eccentricity and on the true angle between the stellar rotation axis and planetary orbit (as opposed to the angle between the projections of those axes on the sky).
22394. Transit light curves of TRAPPIST-1 planets
ID:
ivo://CDS.VizieR/J/AJ/156/218
Title:
Transit light curves of TRAPPIST-1 planets
Short Name:
J/AJ/156/218
Date:
21 Oct 2021
Publisher:
CDS
Description:
The TRAPPIST-1 planetary system provides an exceptional opportunity for the atmospheric characterization of temperate terrestrial exoplanets with the upcoming James Webb Space Telescope (JWST). Assessing the potential impact of stellar contamination on the planets' transit transmission spectra is an essential precursor to this characterization. Planetary transits themselves can be used to scan the stellar photosphere and to constrain its heterogeneity through transit depth variations in time and wavelength. In this context, we present our analysis of 169 transits observed in the optical from space with K2 and from the ground with the SPECULOOS and Liverpool telescopes. Combining our measured transit depths with literature results gathered in the mid-/near-IR with Spitzer/IRAC and HST/WFC3, we construct the broadband transmission spectra of the TRAPPIST-1 planets over the 0.8-4.5 {mu}m spectral range. While planet b, d, and f spectra show some structures at the 200-300 ppm level, the four others are globally flat. Even if we cannot discard their instrumental origins, two scenarios seem to be favored by the data: a stellar photosphere dominated by a few high-latitude giant (cold) spots, or, alternatively, by a few small and hot (3500-4000 K) faculae. In both cases, the stellar contamination of the transit transmission spectra is expected to be less dramatic than predicted in recent papers. Nevertheless, based on our results, stellar contamination can still be of comparable or greater order than planetary atmospheric signals at certain wavelengths. Understanding and correcting the effects of stellar heterogeneity therefore appears essential for preparing for the exploration of TRAPPIST-1 with JWST.
22395. Transit light curves of WASP-10 b
ID:
ivo://CDS.VizieR/J/A+A/535/A7
Title:
Transit light curves of WASP-10 b
Short Name:
J/A+A/535/A7
Date:
21 Oct 2021
Publisher:
CDS
Description:
The WASP-10 planetary system is intriguing because different values of radius have been reported for its transiting exoplanet. The host star exhibits activity in terms of photometric variability, which is caused by the rotational modulation of the spots. Moreover, a periodic modulation has been discovered in transit timing of WASP-10 b, which could be a sign of an additional body perturbing the orbital motion of the transiting planet. We attempt to refine the physical parameters of the system, in particular the planetary radius, which is crucial for studying the internal structure of the transiting planet. We also determine new mid-transit times to confirm or refute observed anomalies in transit timing. We acquired high-precision light curves for four transits of WASP-10 b in 2010. Assuming various limb-darkening laws, we generated best-fit models and redetermined parameters of the system. The prayer-bead method and Monte Carlo simulations were used to derive error estimates. Three transit light curves exhibit signatures of the occultations of dark spots by the planet during its passage across the stellar disk. The influence of stellar activity on transit depth is taken into account while determining system parameters. The radius of WASP-10 b is found to be no greater than 1.03^+0.07^_-0.03_ Jupiter radii, a value significantly smaller than most previous studies indicate. We calculate interior structure models of the planet, assuming a two-layer structure with one homogeneous envelope atop a rock core. The high value of the WASP-10 b's mean density allows one to consider the planet's internal structure including 270 to 450 Earth masses of heavy elements. Our new mid-transit times confirm that transit timing cannot be explained by a constant period if all literature data points are considered. They are consistent with the ephemeris assuming a periodic variation of transit timing. We show that possible starspot features affecting the transit's ingress or egress cannot reproduce variations in transit timing at the observed amplitude.
22396. Transit light curves of WASP-104b
ID:
ivo://CDS.VizieR/J/MNRAS/500/5420
Title:
Transit light curves of WASP-104b
Short Name:
J/MNRAS/500/5420
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical transmission spectrum of the hot Jupiter WASP-104b based on one transit observed by the blue and red channels of the DBSP spectrograph at the Palomar 200-inch telescope and 14 transits observed by the MuSCAT2 four-channel imager at the 1.52m Telescopio Carlos Sanchez. We also analyse 45 additional K2 transits, after correcting for the flux contamination from a companion star. Together with the transit light curves acquired by DBSP and MuSCAT2, we are able to revise the system parameters and orbital ephemeris, confirming that no transit timing variations exist. Our DBSP and MuSCAT2 combined transmission spectrum reveals an enhanced slope at wavelengths shorter than 630nm and suggests the presence of a cloud deck at longer wavelengths. While the Bayesian spectral retrieval analyses favour a hazy atmosphere, stellar spot contamination cannot be completely ruled out. Further evidence, from transmission spectroscopy and detailed characterisation of the host star's activity, is required to distinguish the physical origin of the enhanced slope.
22397. Transit metric for Q1-Q17 Kepler candidates
ID:
ivo://CDS.VizieR/J/ApJ/812/46
Title:
Transit metric for Q1-Q17 Kepler candidates
Short Name:
J/ApJ/812/46
Date:
21 Oct 2021
Publisher:
CDS
Description:
We describe a new metric that uses machine learning to determine if a periodic signal found in a photometric time series appears to be shaped like the signature of a transiting exoplanet. This metric uses dimensionality reduction and k-nearest neighbors to determine whether a given signal is sufficiently similar to known transits in the same data set. This metric is being used by the Kepler Robovetter to determine which signals should be part of the Q1-Q17 DR24 catalog of planetary candidates. The Kepler Mission reports roughly 20000 potential transiting signals with each run of its pipeline, yet only a few thousand appear to be sufficiently transit shaped to be part of the catalog. The other signals tend to be variable stars and instrumental noise. With this metric, we are able to remove more than 90% of the non-transiting signals while retaining more than 99% of the known planet candidates. When tested with injected transits, less than 1% are lost. This metric will enable the Kepler mission and future missions looking for transiting planets to rapidly and consistently find the best planetary candidates for follow-up and cataloging.
22398. Transit observations of GJ1214b
ID:
ivo://CDS.VizieR/J/A+A/538/A46
Title:
Transit observations of GJ1214b
Short Name:
J/A+A/538/A46
Date:
21 Oct 2021
Publisher:
CDS
Description:
GJ1214b, the 6.55 Earth-mass transiting planet recently discovered by the MEarth team, has a mean density of 35% of that of the Earth. It is thought that this planet is either a mini-Neptune, consisting of a rocky core with a thick, hydrogen-rich atmosphere, or a planet with a composition dominated by water. In the case of a hydrogen-rich atmosphere, molecular absorption and scattering processes may result in detectable radius variations as a function of wavelength. The aim of this paper is to measure these variations. We have obtained observations of the transit of GJ1214b in the r- and I-band with the Isaac Newton Telescope (INT), in the g-, r-, i- and z-bands with the 2.2m MPI/ESO telescope, in the Ks-band with the Nordic Optical Telescope (NOT), and in the Kc-band with the William Herschel Telescope (WHT). By comparing the transit depth between the the different bands, which is a measure for the planet-to-star size ratio, the atmosphere is investigated. We do not detect clearly significant variations in the planet-to-star size ratio as function of wavelength. Although the ratio at the shortest measured wavelength, in g-band, is 2sigma larger than in the other bands. The uncertainties in the Ks and Kc bands are large, due to systematic features in the light curves. The tentative increase in the planet-to-star size ratio at the shortest wavelength could be a sign of an increase in the effective planet-size due to Rayleigh scattering, which would require GJ1214b to have a hydrogen-rich atmosphere. If true, then the atmosphere has to have both clouds, to suppress planet-size variations at red optical wavelengths, as well as a sub-solar metallicity, to suppress strong molecular features in the near- and mid-infrared However, star spots, which are known to be present on the hoststar's surface, can (partly) cancel out the expected variations in planet-to-star size ratio, because the lower surface temperature of the spots causes the effective size of the star to vary with wavelength. A hypothetical spot-fraction of 10%, corresponding to an average stellar dimming of 5% in the i-band, would be able to raise the near- and mid-infrared points sufficiently with respect to the optical measurements to be inconsistent with a water-dominated atmosphere. Modulation of the spot fraction due to the stellar rotation would in such case cause the observed flux variations of GJ1214.
22399. Transit observations of the super-Earth GJ1214b
ID:
ivo://CDS.VizieR/J/A+A/565/A7
Title:
Transit observations of the super-Earth GJ1214b
Short Name:
J/A+A/565/A7
Date:
21 Oct 2021
Publisher:
CDS
Description:
GJ 1214b is one of the few known transiting super-Earth-sized exoplanets with a measured mass and radius. It orbits an M-dwarf, only 14.55pc away, making it a favorable candidate for follow-up studies. However, the composition of GJ 1214b's mysterious atmosphere has yet to be fully unveiled. Our goal is to distinguish between the various proposed atmospheric models to explain the properties of GJ 1214b: hydrogen-rich or hydrogen-He mix, or a heavy molecular weight atmosphere with reflecting high clouds, as latest studies have suggested. Wavelength-dependent planetary radii measurements from the transit depths in the optical/NIR are the best tool to investigate the atmosphere of GJ 1214b. We present here (i) photometric transit observations with a narrow-band filter centered on 2.14-microns and a broad-band I-Bessel filter centered on 0.8665-microns, and (ii) transmission spectroscopy in the H and K atmospheric windows that cover three transits. The obtained photometric and spectrophotometric time series were analyzed with MCMC simulations to measure the planetary radii as a function of wavelength. We determined radii ratios of 0.1173 for I-Bessel and 0.11735 at 2.14-microns. Our measurements indicate a flat transmission spectrum, in agreement with last atmospheric models that favor featureless spectra with clouds and high molecular weight compositions.
22400. Transit of exoplanet HD 17156b
ID:
ivo://CDS.VizieR/J/ApJ/693/794
Title:
Transit of exoplanet HD 17156b
Short Name:
J/ApJ/693/794
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometry is presented of the 2007 December 25 transit of HD 17156b, which has the longest orbital period and highest orbital eccentricity of all the known transiting exoplanets. New measurements of the stellar radial velocity are also presented. All the data are combined and integrated with stellar-evolutionary modeling to derive refined system parameters.

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