- ID:
- ivo://CDS.VizieR/J/A+A/528/A111
- Title:
- GJ3634 radial velocity and 4.5um flux
- Short Name:
- J/A+A/528/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the detection of GJ3634b, a super-Earth of mass msini=7.0+/-0.9 Mearth and period P=2.64561+/-0.00066-day. Its host star is a M2.5 dwarf, has a mass of 0.45+/-0.05M_{sun}_, a radius of 0.43+/-0.03R_{sun}_ and lies 19.8+/-0.6pc away from our Sun. The planet is detected after a radial-velocity campaign using the ESO/Harps spectrograph. GJ3634b had an a priori geometric probability to undergo transit of ~7% and, if telluric in composition, a non-grazing transit would produce a photometric dip of <~0.1%. We therefore followed-up upon the RV detection with photometric observations using the 4.5-um band of the IRAC imager onboard Spitzer. Our six-hour long light curve excludes that a transit occurs for 2sigma of the probable transit window, decreasing the probability that GJ3634b undergoes transit to ~0.5%.
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- ID:
- ivo://CDS.VizieR/J/A+A/507/487
- Title:
- GJ 581 radial velocity curve
- Short Name:
- J/A+A/507/487
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The GJ 581 planetary system is already known to harbour three planets, including two super-Earth planets that straddle its habitable zone. We report the detection of an additional planet - GJ 581e - with a minimum mass of 1.9M_{earth}_. With a period of 3.15 days, it is the innermost planet of the system and has a ~5% transit probability. We also correct our previous confusion about the orbital period of GJ 581d (the outermost planet) with a one-year alias, benefitting from an extended time span and many more measurements. The revised period is 66.8 days, and positions the semi-major axis inside the habitable zone of the low mass star. The dynamical stability of the 4-planet system imposes an upper bound on the orbital plane inclination. The planets cannot be more massive than approximately 1.6 times their minimum mass.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A117
- Title:
- GJ 3998 RVs, S and Halpha indexes
- Short Name:
- J/A+A/593/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- M dwarfs are considered ideal targets for Doppler radial velocity searches. Nonetheless, the statistics of frequency of low-mass planets hosted by low mass stars remains poorly constrained. Our M-dwarf radial velocity monitoring with HARPS-N can provide a major contribution to the widening of the current statistics through the in-depth analysis of accurate radial velocity observations in a narrow range of spectral sub-types (79 stars, between dM0 to dM3). Spectral accuracy will enable us to reach the precision needed to detect small planets with a few earth masses. Our survey will bring a contribute to the surveys devoted to the search for planets around M-dwarfs, mainly focused on the M-dwarf population of the northern hemisphere, for which we will provide an estimate of the planet occurence. We present here a long duration radial velocity monitoring of the M1 dwarf star GJ 3998 with HARPS-N to identify periodic signals in the data. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programs to characterize the stellar activity and to distinguish from the periodic signals those due to activity and to the presence of planetary companions. The radial velocities have a dispersion in excess of their internal errors due to at least four superimposed signals, with periods of 30.7, 13.7, 42.5 and 2.65-days. The analysis of spectral indices based on Ca II H & K and H{alpha} lines demonstrates that the periods of 30.7 and 42.5-days are due to chromospheric inhomogeneities modulated by stellar rotation and differential rotation. The shorter periods of 13.74+/-0.02d and 2.6498+/-0.0008d are well explained with the presence of two planets, with minimum masses of 6.26+/-0.79M_Earth_ and 2.47+/-0.27M_Earth_ and distances of 0.089AU and 0.029AU from the host, respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/563/A21
- Title:
- GJ 1214 Trappist and Spitzer light curves
- Short Name:
- J/A+A/563/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-precision eclipse spectrophotometry of transiting terrestrial exoplanets represents a promising path for the first atmospheric characterizations of habitable worlds and the search for life outside our solar system. The detection of terrestrial planets transiting nearby late-type M-dwarfs could make this approach applicable within the next decade, with soon-to-come general facilities. In this context, we previously identified GJ 1214 as a high-priority target for a transit search, as the transit probability of a habitable planet orbiting this nearby M4.5 dwarf would be significantly enhanced by the transiting nature of GJ 1214 b, the super-Earth already known to orbit the star. Based on this observation, we have set up an ambitious high-precision photometric monitoring of GJ 1214 with the Spitzer Space Telescope to probe the inner part of its habitable zone in search of a transiting planet as small as Mars. We present here the results of this transit search.
- ID:
- ivo://CDS.VizieR/J/A+A/493/645
- Title:
- Gl 176 radial velocities
- Short Name:
- J/A+A/493/645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A 10.24-day Neptune-mass planet was recently announced as orbiting the nearby M2 dwarf Gl 176, based on 28 radial velocities measured with the HRS spectrograph on the Hobby-Heberly Telescope. We obtained 57 radial velocities of Gl 176 with the ESO 3.6m telescope and the HARPS spectrograph, which is known for its sub-m/s stability. The median photon-noise standard error of our measurements is 1.1m/s, and the 4-year period over which they were obtained overlaps considerably with the epochs of the HET measurements. The HARPS measurements show no evidence of a signal at the period of the putative HET planet, suggesting that its detection was spurious. We do find, on the other hand, strong evidence of a lower mass 8.4M_Earth_ planet, in a quasi-circular orbit and at the different period of 8.78 days.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/95
- Title:
- g'RcIcJ photometry of the hot Uranus GJ3470b
- Short Name:
- J/ApJ/770/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical (g', R_c_, and I_c_) to near-infrared (J) simultaneous photometric observations for a primary transit of GJ3470b, a Uranus-mass transiting planet around a nearby M dwarf, by using the 50cm MITSuME telescope and the 188cm telescope, both at the Okayama Astrophysical Observatory. From these data, we derive the planetary mass, radius, and density as 14.1 +/-1.3M_{Earth}_, 4.32_-0.10_^+0.21^R_{Earth}_, and 0.94+/-0.12g/cm3, respectively, thus confirming the low density that was reported by Demory et al. (2013ApJ...768..154D) based on the Spitzer/IRAC 4.5{mu}m photometry (0.72_-0.12_^+0.13^g/cm3). Although the planetary radius is about 10% smaller than that reported by Demory et al., this difference does not alter their conclusion that the planet possesses a hydrogen-rich envelope whose mass is approximately 10% of the planetary total mass. On the other hand, we find that the planet-to-star radius ratio (R_p_/R_s_) in the J band (0.07577_-0.00075_^+0.00072^) is smaller than that in the I_c_(0.0802+/-0.0013) and 4.5{mu}m (0.07806_-0.00054_^+0.00052^) bands by 5.8%+/-2.0% and 2.9%+/-1.1%, respectively. A plausible explanation for the differences is that the planetary atmospheric opacity varies with wavelength due to absorption and/or scattering by atmospheric molecules. Although the significance of the observed R_p_/R_s_variations is low, if confirmed, this fact would suggest that GJ3470b does not have a thick cloud layer in the atmosphere. This property would offer a wealth of opportunity for future transmission-spectroscopic observations of this planet to search for certain molecular features, such as H_2_O, CH_4_, and CO, without being prevented by clouds.
- ID:
- ivo://CDS.VizieR/J/A+A/589/A62
- Title:
- GTC transit light curves of CoRoT-29b
- Short Name:
- J/A+A/589/A62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The launch of the exoplanet space missions obtaining exquisite photometry from space has resulted in the discovery of thousands of planetary systems with very different physical properties and architectures. Among them, the exoplanet CoRoT-29b was identified in the light curves the mission obtained in summer 2011, and presented an asymmetric transit light curve, which was tentatively explained via the effects of gravity darkening. Here we use the OSIRIS spectrograph at the 10-m GTC telescope to measure with high precision the transit light curve of CoRoT-29b to characterize the reported asymmetry in its transit shape. To this end, using the OSIRIS spectrograph at the 10-m GTC telescope, we perform spectro-photometric differential observations, which allow us to both calculate a high-accuracy photometric light curve, and a study of the color-dependence of the transit. After careful data analysis, we find that there is no asymmetry in the transit of CoRoT-29b, in either of the two observed transits, separated by one calendar year. Due to the relative faintness of the star, we do not reach the precision necessary to perform transmission spectroscopy of its atmosphere, but we see no signs of color-dependency of the transit depth or duration. We conclude that the previously reported asymmetry is a time-dependent phenomenon which did not occur in more recent epochs, or possible instrumental effects in the discovery data need to be reconsidered.
- ID:
- ivo://CDS.VizieR/J/A+A/594/A65
- Title:
- GTC transit light curves of HAT-P-32b
- Short Name:
- J/A+A/594/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the hot Jupiter HAT-P-32b (also known as HAT-P-32Ab) to determine its optical transmission spectrum by measuring the wavelength-dependent, planet-to-star radius ratios in the region between 518-918nm. We used the OSIRIS instrument at the Gran Telescopio CANARIAS (GTC) in long-slit spectroscopy mode, placing HAT-P-32 and a reference star in the same slit and obtaining a time series of spectra covering two transit events. Using the best quality data set, we were able to yield 20 narrowband transit light curves, with each passband spanning a 20nm wide interval. After removal of all systematic noise signals and light curve modeling, the uncertainties for the resulting radius ratios lie between 337 and 972ppm. The radius ratios show little variation with wavelength, suggesting a high altitude cloud layer masking any atmospheric features. Alternatively, a strong depletion in alkali metals or a much smaller than expected planetary atmospheric scale height could be responsible for the lack of atmospheric features. Our result of a flat transmission spectrum is consistent with a previous ground-based study of the optical spectrum of this planet. This agreement between independent results demonstrates that ground-based measurements of exoplanet atmospheres can give reliable and reproducible results despite the fact that the data often is heavily affected by systematic noise as long as the noise source is well understood and properly corrected.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A158
- Title:
- GTC transit light curves of WASP-69b
- Short Name:
- J/A+A/641/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the major atmospheric features in exoplanet atmospheres, detectable both from ground- and space-based facilities, is Rayleigh scattering. In hydrogen-dominated planetary atmospheres Rayleigh scattering causes the measured planetary radius to increase towards blue wavelengths in the optical range. We obtained a spectrophotometic time series of one transit of the Saturn-mass planet WASP-69b using the OSIRIS instrument at the Gran Telescopio Canarias. From the data we construct 19 spectroscopic transit light curves representing 20nm wide wavelength bins spanning from 515nm-905nm. We derive the transit depth for each curve individually by fitting an analytical model together with a Gaussian Processes to account for systematic noise in the light curves. We find that the transit depth increases towards bluer wavelengths, indicative of a larger effective planet radius. Our results are consistent with space-based measurements obtained in the near infrared using the Hubble Space telescope, which show a compatible slope of the transmission spectrum. We discuss the origin of the detected slope and argue between two possible scenarios: a Rayleigh scattering detection originating in the planet's atmosphere or a stellar activity induced signal from the host star.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A145
- Title:
- GTC transit light curves of WASP-127b
- Short Name:
- J/A+A/616/A145
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanets with relatively clear atmospheres are prime targets for detailed studies of chemical compositions and abundances in their atmospheres. Alkali metals have been long suggested to exhibit broad wings due to pressure broadening, but most of the alkali detections only show very narrow absorption cores, probably due to the presence of clouds. Here we report the strong detection of the pressure-broadened spectral profiles of Na, K, and Li absorption in the atmosphere of the super-Neptune WASP-127b, at 5.0{sigma}, 4.1{sigma}, and 3.4{sigma}, respectively. We performed a spectral retrieval modeling on the high-quality optical transmission spectrum newly acquired with the 10.4m Gran Telescopio Canarias (GTC), in combination with the re-analyzed optical transmission spectrum obtained with the 2.5m Nordic Optical Telescope (NOT). By assuming a patchy cloudy model, we retrieved the abundances of Na, K, and Li, which are super-solar at 3.7{sigma} for K and 5.1{sigma} for Li (and only 1.8{sigma} for Na). We constrained the presence of haze coverage to be around 52%. We also found a hint of water absorption, but cannot constrain it with the global retrieval due to larger uncertainties in the probed wavelengths. WASP-127b will be extremely valuable for atmospheric characterization in the era of James Webb space telescope.
