- ID:
- ivo://CDS.VizieR/J/A+A/658/A36
- Title:
- Transition disks around evolved stars
- Short Name:
- J/A+A/658/A36
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Post-AGB binaries are surrounded by massive disks of gas and dust that are similar to protoplanetary disks surrounding young stars. We assembled a catalog of all known Galactic post-AGB binaries with disks. We explore correlations between the different observables with the aim to learn more about potential disk-binary interactions. We compiled spectral energy distributions of 85 Galactic post-AGB binary systems. We built-up a color-color diagram to differentiate between the different disk morphologies traced by the characteristics of the infrared excess. We categorised different disk types and looked for correlations with other observational characteristics of these systems. 8 to 12% of our targets are surrounded by transition disks, i.e. disks having no or low near-infrared excesses. We find a strong link between these transition disks and the depletion of refractory elements seen on the surface of the post-AGB star. We interpret this correlation as evidence for the presence of a mechanism that stimulates the dust and gas separation within the disk and which also produces the transition disk structure. We propose that such a mechanism can be a giant planet carving a hole in the disk which traps the dust in the outer disk parts. We propose two disk evolutionary scenarios, depending on the presence of such a giant planet in the disk. We advocate that giant planets can successfully explain the correlation between the transition disks and the depletion of refractory materials observed in post-AGB binaries. If the planetary scenario is confirmed, disks around post-AGB binaries could be a unique laboratory to test planet-disk interactions and their influence on the late evolution of binary stars. Whether the planets are first or second generation also remains to be studied. We argue that these disks are the perfect place to study planet formation scenarios in an unprecedented parameter space.
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- ID:
- ivo://CDS.VizieR/J/other/ExA/51.109
- Title:
- Transit KELT-11b observed by CHEOPS
- Short Name:
- J/other/ExA/51.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CHaracterising ExOPlanet Satellite (CHEOPS) was selected on October 19, 2012, as the first small mission (S-mission) in the ESA Science Programme and successfully launched on December 18, 2019, as a secondary passenger on a Soyuz-Fregat rocket from Kourou, French Guiana. CHEOPS is a partnership between ESA and Switzerland with important contributions by ten additional ESA Member States. CHEOPS is the first mission dedicated to search for transits of exoplanets using ultrahigh precision photometry on bright stars already known to host planets. As a follow-up mission, CHEOPS is mainly dedicated to improving, whenever possible, existing radii measurements or provide first accurate measurements for a subset of those planets for which the mass has already been estimated from ground-based spectroscopic surveys. The expected photometric precision will also allow CHEOPS to go beyond measuring only transits and to follow phase curves or to search for exo-moons, for example. Finally, by unveiling transiting exoplanets with high potential for in-depth characterisation, CHEOPS will also provide prime targets for future instruments suited to the spectroscopic characterisation of exoplanetary atmospheres. To reach its science objectives, requirements on the photometric precision and stability have been derived for stars with magnitudes ranging from 6 to 12 in the V band. In particular, CHEOPS shall be able to detect Earth-size planets transiting G5 dwarf stars (stellar radius of 0.9R_sun_) in the magnitude range 6<V<9 by achieving a photometric precision of 20 ppm in 6 hours of integration time. In the case of K-type stars (stellar radius of 0.7R_{sun}_) of magnitude in the range 9<V<12, CHEOPS shall be able to detect transiting Neptune-size planets achieving a photometric precision of 85ppm in 3 hours of integration time. This precision has to be maintained over continuous periods of observation for up to 48 hours. This precision and stability will be achieved by using a single, frame-transfer, back-illuminated CCD detector at the focal plane assembly of a 33.5cm diameter, on-axis Ritchey-Chretien telescope. The nearly 275kg spacecraft is nadir-locked, with a pointing accuracy of about 1arcsec rms, and will allow for at least 1Gbit/day downlink. The sun-synchronous dusk-dawn orbit at 700km altitude enables having the Sun permanently on the backside of the spacecraft thus minimising Earth stray light. A mission duration of 3.5 years in orbit is foreseen to enable the execution of the science programme. During this period, 20% of the observing time is available to the wider community through yearly ESA call for proposals, as well as through discretionary time approved by ESA's Director of Science. At the time of this writing, CHEOPS commissioning has been completed and CHEOPS has been shown to fulfill all its requirements. The mission has now started the execution of its science programme.
- ID:
- ivo://CDS.VizieR/J/ApJ/736/12
- Title:
- Transit light curves of GJ1214
- Short Name:
- J/ApJ/736/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The super-Earth GJ1214b transits a nearby M dwarf that exhibits a 1% intrinsic variability in the near-infrared. Here, we analyze new observations to refine the physical properties of both the star and planet. We present three years of out-of-transit photometric monitoring of the stellar host GJ1214 from the MEarth Observatory and find the rotation period to be long, most likely an integer multiple of 53 days, suggesting low levels of magnetic activity and an old age for the system. We show that such variability will not pose significant problems to ongoing studies of the planet's atmosphere with transmission spectroscopy. We analyze two high-precision transit light curves from ESO's Very Large Telescope (VLT) along with seven others from the MEarth and Fred Lawrence Whipple Observatory 1.2m telescopes, finding physical parameters for the planet that are consistent with previous work. The VLT light curves show tentative evidence for spot occultations during transit. Using two years of MEarth light curves, we place limits on additional transiting planets around GJ1214 with periods out to the habitable zone of the system. We also improve upon the previous photographic V-band estimate for the star, finding V=14.71+/-0.03.
- 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}_.
- 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.
- 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/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.
- 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.
