- ID:
- ivo://CDS.VizieR/J/ApJ/726/L19
- Title:
- Gunn r photometry of WASP-30
- Short Name:
- J/ApJ/726/L19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of a 61-Jupiter-mass brown dwarf (BD), which transits its F8V host star, WASP-30, every 4.16 days. From a range of age indicators we estimate the system age to be 1-2Gyr. We derive a radius (0.89+/-0.02R_Jup_) for the companion that is consistent with that predicted (0.914R_Jup_) by a model of a 1Gyr old, non-irradiated BD with a dusty atmosphere. The location of WASP-30b in the minimum of the mass-radius relation is consistent with the quantitative prediction of Chabrier & Baraffe, thus confirming the theory.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/608/A63
- Title:
- HADES VI. GJ 3942b activity with HARPS-N
- Short Name:
- J/A+A/608/A63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Short- to mid-term magnetic phenomena on the stellar surface of M-type stars can resemble the effects of planets in radial velocity data, and may also hide them. We analyze 145 spectroscopic HARPS-N observations of GJ 3942 taken over the past five years and additional photometry in order to disentangle stellar activity effects from genuine Doppler signals as a result of the orbital motion of the star around the common barycenter with its planet. To achieve this, we use the common methods of pre-whitening, and treat the correlated red noise by a first-order moving average term and by Gaussian-process regression following an MCMC analysis. We identify the rotational period of the star at 16.3-days and discover a new super-Earth, GJ 3942b, with an orbital period of 6.9-days and a minimum mass of 7.1M_Earth_. An additional signal in the periodogram of the residuals is present, but at this point we cannot claim with sufficient significance that it is related to a second planet. If confirmed, this planet candidate would have a minimum mass of 6.3M_Earth_ and a period of 10.4-days, which might indicate a 3:2 mean-motion resonance with the inner planet.
- ID:
- ivo://CDS.VizieR/J/A+A/596/A76
- Title:
- H{alpha}-activity in the SARG binary survey
- Short Name:
- J/A+A/596/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar activity influences radial velocity (RV) measurements and can also mimic the presence of orbiting planets. As part of the search for planets around the components of wide binaries performed with the SARG High Resolution Spectrograph at the TNG, it was discovered that HD 200466A shows strong variation in RV that is well correlated with the activity index based on H{alpha}. We used SARG to study the H{alpha} line variations in each component of the binaries and a few bright stars to test the capability of the H{alpha} index of revealing the rotation period or activity cycle. We also analysed the relations between the average activity level and other physical properties of the stars. We finally tried to reveal signals in the RVs that are due to the activity. At least in some cases the variation in the observed RVs is due to the stellar activity. We confirm that H{alpha} can be used as an activity indicator for solar-type stars and as an age indicator for stars younger than 1.5Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJ/890/86
- Title:
- H{alpha} spectra & V-band photometry of {delta} Sco
- Short Name:
- J/ApJ/890/86
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- We model the circumstellar disk of {delta} Sco using the three-dimensional Monte Carlo radiative transfer code HDUST in order to quantify the large-scale changes in the disk through the years 2000-2018, and to see if these changes can be attributed to the secondary star affecting the disk throughout its orbit. We determine our best-fitting models through matching simulated observations to actual H{alpha} spectroscopy and V-band photometric observations. Our modeling results confirm previous findings that the disk of {delta}Sco was forming early in the century. We also find a period of disk dissipation when the companion is at apastron, as well as a significant growth of the disk between 2009 and 2011, prior to the periastron of 2011. Due to the steady-state nature of the disk after 2011, it is difficult to say whether the variations seen are due to the effect of the close passage of the binary companion.
- ID:
- ivo://CDS.VizieR/J/A+A/515/A26
- Title:
- H and Ks photometry of Trumpler 14
- Short Name:
- J/A+A/515/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present adaptive optics (AO) near-infrared observations of the core of the Tr 14 cluster in the Carina region obtained with the ESO multi-conjugate AO demonstrator, MAD. Our campaign yields AO-corrected observations with an image quality of about 0.2' across the 2" field of view, which is the widest AO mosaic ever obtained. We detected almost 2000 sources spanning a dynamic range of 10 mag. The pre-main sequence (PMS) locus in the colour-magnitude diagram is well reproduced by Palla & Stahler isochrones with an age of 3 to 5x10^5^yr, confirming the very young age of the cluster. We derive a very high (deprojected) central density n_0_~4.5(+/-0.5)x10^4^pc^-3^ and estimate the total mass of the cluster to be about ~4.3^+3.3^_-1.5_x10^3^M_{sun}_, although contamination of the field of view might have a significant impact on the derived mass. We show that the pairing process is largely dominated by chance alignment so that physical pairs are difficult to disentangle from spurious ones based on our single epoch observation. Yet, we identify 150 likely bound pairs, 30% of these with a separation smaller than 0.5" (~1300AU). We further show that at the 2{sigma} level massive stars have more companions than lower-mass stars and that those companions are respectively brighter on average, thus more massive. Finally, we find some hints of mass segregation for stars heavier than about 10M_{sun}_. If confirmed, the observed degree of mass segregation could be explained by dynamical evolution, despite the young age of the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/792/L31
- Title:
- HARPS and HARPS-N 55 Cnc radial velocities
- Short Name:
- J/ApJ/792/L31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Rossiter-McLaughlin observations of the transiting super-Earth 55 Cnc e collected during six transit events between 2012 January and 2013 November with HARPS and HARPS-N. We detect no radial velocity signal above 35 cm/s (3{sigma}) and confine the stellar vsini_*_ to 0.2+/-0.5 km/s. The star appears to be a very slow rotator, producing a very low amplitude Rossiter-McLaughlin effect. Given such a low amplitude, the Rossiter-McLaughlin effect of 55 Cnc e is undetected in our data, and any spin-orbit angle of the system remains possible. We also performed Doppler tomography and reach a similar conclusion. Our results offer a glimpse of the capacity of future instrumentation to study low amplitude Rossiter-McLaughlin effects produced by super-Earths.
- ID:
- ivo://CDS.VizieR/J/AJ/155/107
- Title:
- HARPS-N observations of K2-141 planetary system
- Short Name:
- J/AJ/155/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ultra-short period (USP) planets are a class of low-mass planets with periods shorter than one day. Their origin is still unknown, with photo-evaporation of mini-Neptunes and in situ formation being the most credited hypotheses. Formation scenarios differ radically in the predicted composition of USP planets, and it is therefore extremely important to increase the still limited sample of USP planets with precise and accurate mass and density measurements. We report here the characterization of a USP planet with a period of 0.28 days around K2-141 (EPIC 246393474), and the validation of an outer planet with a period of 7.7 days in a grazing transit configuration. We derived the radii of the planets from the K2 light curve and used high-precision radial velocities gathered with the HARPS-N spectrograph for mass measurements. For K2-141b, we thus inferred a radius of 1.51+/-0.05 R_{Earth}_ and a mass of 5.08+/-0.41 M_{Earth}_, consistent with a rocky composition and lack of a thick atmosphere. K2-141c is likely a Neptune-like planet, although due to the grazing transits and the non-detection in the RV data set, we were not able to put a strong constraint on its density. We also report the detection of secondary eclipses and phase curve variations for K2-141b. The phase variation can be modeled either by a planet with a geometric albedo of 0.30+/-0.06 in the Kepler bandpass, or by thermal emission from the surface of the planet at ~3000 K. Only follow-up observations at longer wavelengths will allow us to distinguish between these two scenarios.
- ID:
- ivo://CDS.VizieR/J/AJ/152/204
- Title:
- HARPS-N radial velocities of HD 179070
- Short Name:
- J/AJ/152/204
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HD 179070, aka Kepler-21, is a V=8.25 F6IV star and the brightest exoplanet host discovered by Kepler. An early detailed analysis by Howell et al. of the first 13 months (Q0-Q5) of Kepler light curves revealed transits of a planetary companion, Kepler-21b, with a radius of about 1.60+/-0.04R_{Earth}_ and an orbital period of about 2.7857days. However, they could not determine the mass of the planet from the initial radial velocity (RV) observations with Keck-HIRES, and were only able to impose a 2{sigma} upper limit of 10M_{Earth}_. Here, we present results from the analysis of 82 new RV observations of this system obtained with HARPS-N, together with the existing 14 HIRES data points. We detect the Doppler signal of Kepler-21b with a RV semiamplitude K=2.00+/-0.65ms^-1^, which corresponds to a planetary mass of 5.1+/-1.7M_{Earth}_. We also measure an improved radius for the planet of 1.639 +0.019/-0.015R_{Earth}_, in agreement with the radius reported by Howell et al. We conclude that Kepler-21b, with a density of 6.4+/-2.1gcm^-3^, belongs to the population of small, <~6M_{Earth}_ planets with iron and magnesium silicate interiors, which have lost the majority of their envelope volatiles via stellar winds or gravitational escape. The RV analysis presented in this paper serves as an example of the type of analysis that will be necessary to confirm the masses of TESS small planet candidates.
- ID:
- ivo://CDS.VizieR/J/AJ/152/160
- Title:
- HARPS-N radial velocities of KOI-70
- Short Name:
- J/AJ/152/160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-20 is a solar-type star (V=12.5) hosting a compact system of five transiting planets, all packed within the orbital distance of Mercury in our own solar system. A transition from rocky to gaseous planets with a planetary transition radius of ~1.6R_{Earth}_ has recently been proposed by several articles in the literature. Kepler-20b (R_p_~1.9R_{Earth}_) has a size beyond this transition radius; however, previous mass measurements were not sufficiently precise to allow definite conclusions to be drawn regarding its composition. We present new mass measurements of three of the planets in the Kepler-20 system that are facilitated by 104 radial velocity measurements from the HARPS-N spectrograph and 30 archival Keck/HIRES observations, as well as an updated photometric analysis of the Kepler data and an asteroseismic analysis of the host star (M_*_=0.948+/-0.051M_{Sun}_ and R_*_=0.964+/-0.018R_{Sun}_). Kepler-20b is a 1.868_-0.034_^+0.066^R_{Earth}_ planet in a 3.7day period with a mass of 9.70_-1.44_^+1.41^M_{Earth}_, resulting in a mean density of 8.2_-1.3_^+1.5^g/cm^3^, indicating a rocky composition with an iron-to-silicate ratio consistent with that of the Earth. This makes Kepler-20b the most massive planet with a rocky composition found to date. Furthermore, we report the discovery of an additional non-transiting planet with a minimum mass of 19.96_-3.61_^+3.08^M_{Earth}_ and an orbital period of ~34days in the gap between Kepler-20f (P~11days) and Kepler-20d (P~78days).
- ID:
- ivo://CDS.VizieR/J/ApJ/800/135
- Title:
- HARPS-N radial velocities of KOI-69
- Short Name:
- J/ApJ/800/135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler-93b is a 1.478+/-0.019R_{Earth}_ planet with a 4.7day period around a bright (V=10.2), astroseismically characterized host star with a mass of 0.911+/-0.033M_{sun}_ and a radius of 0.919+/-0.011R_{sun}_. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02+/-0.68M_{Earth}_. The corresponding high density of 6.88+/-1.18g/cm3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6M_{Earth}_, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6M_{Earth}_. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6M_{Earth}_ planets.
