- 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.
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Search Results
- 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.
6925. 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.
- ID:
- ivo://CDS.VizieR/J/A+A/652/A117
- Title:
- Transit search in the V1400 Cen system
- Short Name:
- J/A+A/652/A117
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In 2007, the young star 1SWASP J140747.93-394542.6 (V1400 Cen) underwent a complex series of deep eclipses over 56 days. This was attributed to the transit of a ring system filling a large fraction of the Hill sphere of an unseen substellar companion. Subsequent photometric monitoring has not found any other deep transits from this candidate ring system, but if there are more substellar companions and if they are coplanar with the potential ring system, there is a chance that they will transit the star as well. This young star is active, and the light curves show a 5% modulation in amplitude with a dominant rotation period of 3.2 days due to starspots rotating into and out of view. We model and remove the rotational modulation of the J1407 light curve and search for additional transit signatures of substellar companions orbiting around J1407. We combine the photometry of J1407 from several observatories, spanning a 19 year baseline. We remove the rotational modulation by modeling the variability as a periodic signal, whose periodicity changes slowly with time over several years due to the activity cycle of the star. A transit least squares (TLS) analysis is used to search for any periodic transiting signals within the cleaned light curve. We identify an activity cycle of J1407 with a period of 5.4yr. A TLS search does not find any plausible periodic eclipses in the light curve, from 1.2% amplitude at 5 days up to 1.9% at 20 days. This sensitivity is confirmed by injecting artificial transits into the light curve and determining the recovery fraction as a function of transit depth and orbital period. J1407 is confirmed as a young active star with an activity cycle consistent with a rapidly rotating solar mass star. With the rotational modulation removed, the TLS analysis reaches down to planetary mass radii for young exoplanets, ruling out transiting companions with radii larger than about 1R_Jup_.
- ID:
- ivo://CDS.VizieR/II/278
- Title:
- Transits observed in OGLE 2001-2003
- Short Name:
- II/278
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of an extensive photometric search for planetary and low-luminosity object transits in the Galactic disk stars commencing the third phase of the Optical Gravitational Lensing Experiment - OGLE-III.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/L5
- Title:
- Transits, occultation times and RVs of WASP-12b
- Short Name:
- J/ApJ/888/L5
- Date:
- 25 Oct 2021 10:19:53
- Publisher:
- CDS
- Description:
- WASP-12b is a transiting hot Jupiter on a 1.09 day orbit around a late-F star. Since the planet's discovery in 2008, the time interval between transits has been decreasing by 29+/-2ms/yr. This is a possible sign of orbital decay, although the previously available data left open the possibility that the planet's orbit is slightly eccentric and is undergoing apsidal precession. Here, we present new transit and occultation observations that provide more decisive evidence for orbital decay, which is favored over apsidal precession by a {Delta}BIC of 22.3 or Bayes factor of 70000. We also present new radial-velocity data that rule out the Romer effect as the cause of the period change. This makes WASP-12 the first planetary system for which we can be confident that the orbit is decaying. The decay timescale for the orbit is P/{dot}P=3.25+/-0.23Myr. Interpreting the decay as the result of tidal dissipation, the modified stellar tidal quality factor is Q_*_^'^=1.8x10^5^.