- 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.
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- 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.
- 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.
- 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.
- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/519/A98
- Title:
- Transit of exoplanet WASP-21b
- Short Name:
- J/A+A/519/A98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of WASP-21b, a new transiting exoplanet discovered by the Wide Angle Search for Planets (WASP) Consortium and established and characterized with the FIES, SOPHIE, CORALIE and HARPS fiber-fed echelle spectrographs. A 4.3-d period, 1.1% transit depth and 3.4-h duration are derived for WASP-21b using SuperWASP-North and high precision photometric observations at the Liverpool Telescope. Simultaneous fitting to the photometric and radial velocity data with a Markov Chain Monte Carlo procedure leads to a planet in the mass regime of Saturn. With a radius of 1.07R_Jup_ and mass of 0.30M_Jup_, WASP-21b has a density close to 0.24{rho}_Jup_ corresponding to the distribution peak at low density of transiting gaseous giant planets. With a host star metallicity [Fe/H] of -0.46, WASP-21b strengthens the correlation between planetary density and host star metallicity for the five known Saturn-like transiting planets. Furthermore there are clear indications that WASP-21b is the first transiting planet belonging to the thick disc.
6928. Transit of HAT-P-5
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/3099
- Title:
- Transit of HAT-P-5
- Short Name:
- J/MNRAS/422/3099
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The radii of giant planets, as measured from transit observations, may vary with wavelength due to Rayleigh scattering or variations in opacity. Such an effect is predicted to be large enough to detect using ground-based observations at multiple wavelengths. We present the defocused photometry of a transit in the HAT-P-5 system, obtained simultaneously through Stroemgren u, Gunn g and r, and Johnson I filters. Two more transit events were observed through a Gunn r filter.
- ID:
- ivo://CDS.VizieR/J/A+A/533/A114
- Title:
- Transit of super-Earth 55 Cnc e
- Short Name:
- J/A+A/533/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the detection of a transit of the super-Earth 55 Cnc e with warm Spitzer in IRAC's 4.5um band.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A183
- Title:
- Transit photometry of NGTS-14Ab
- Short Name:
- J/A+A/646/A183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The sub-Jovian or Neptunian desert is a previously-identified region of parameter space where there is a relative dearth of intermediate- mass planets at short orbital periods. We present the discovery of a new transiting planetary system within the Neptunian desert, NGTS-14A. Transits of NGTS-14Ab were discovered in photometry from the Next Generation Transit Survey (NGTS). Follow-up transit photometry was conducted from several ground-based facilities, as well as extracted from TESS full- frame images. We combine radial velocities from the HARPS spectrograph with the photometry in a global analysis to determine the system parameters. NGTS-14Ab has a radius about 30 per cent larger than that of Neptune (0.444+/-0.030R_Jup_), and is around 70 per cent more massive than Neptune (0.092+/-0.012 M_Jup_). It transits the main-sequence K1 star, NGTS-14A, with a period of 3.54 days, just far enough to have maintained at least some of its primordial atmosphere. We have also identified a possible long-period stellar mass companion to the system, NGTS-14B.
