- ID:
- ivo://CDS.VizieR/J/A+A/638/A5
- Title:
- HD 285507 and AD Leo light and velocity curves
- Short Name:
- J/A+A/638/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The existence of hot Jupiters is still not well understood. Two main channels are thought to be responsible for their current location: a smooth planet migration through the proto-planetary disk or the circularization of an initial high eccentric orbit by tidal dissipation leading to a strong decrease of the semimajor axis. Different formation scenarios result in different observable effects, such as orbital parameters (obliquity/eccentricity), or frequency of planets at different stellar ages. In the context of the GAPS Young-Objects project, we are carrying out a radial velocity survey with the aim to search and characterize young hot-Jupiter planets. Our purpose is to put constraints on evolutionary models and establish statistical properties, such as the frequency of these planets from a homogeneous sample. Since young stars are in general magnetically very active, we performed multi-band (visible and near-infrared) spectroscopy with simultaneous GIANO-B + HARPS-N (GIARPS) observing mode at TNG. This helps to deal with stellar activity and distinguish the nature of radial velocity variations: stellar activity will introduce a wavelength-dependent radial velocity amplitude, whereas a Keplerian signal is achromatic. As a pilot study, we present here the cases of two already claimed hot Jupiters orbiting young stars: HD 285507 b and AD Leo b. Our analysis of simultaneous high-precision GIARPS spectroscopic data confirms the Keplerian nature of HD285507's radial velocities variation and refines the orbital parameters of the hot Jupiter, obtaining an eccentricity consistent with a circular orbit. On the other hand, our analysis does not confirm the signal previously attributed to a planet orbiting AD~Leo. This demonstrates the power of the multi-band spectroscopic technique when observing active stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/597/A137
- Title:
- HD 123999 and Alpha Cen A and B OIFITS files
- Short Name:
- J/A+A/597/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The photospheric radius is one of the fundamental parameters governing the radiative equilibrium of a star. We report new observations of the nearest solar-type stars Alpha Centauri A (G2V) and B (K1V) with the VLTI/PIONIER optical interferometer. The combination of four configurations of the VLTI enable us to measure simultaneously the limb darkened angular diameter thetaLD and the limb darkening parameters of the two solar-type stars in the near-infrared H band (lambda=1.65um). We obtain photospheric angular diameters of {theta}_LD(A)_=8.502+/-0.038mas (0.43%) and {theta}_LD(B)_=5.999+/-0.025mas (0.42%), through the adjustment of a power law limb darkening model. We find H band power law exponents of {alpha}_(A)_=0.1404+/-0.0050 (3.6%) and {alpha}_(B)_=0.1545+/-0.0044 (2.8%), which closely bracket the observed solar value (alpha_{sun}_=0.15027). Combined with the parallax pi=747.17+/-0.61mas determined by Kervella et al. (2016), we derive linear radii of R_A_=1.2234+/-0.0053R_{sun}_ (0.43%) and R_B_=0.8632+/-0.0037R_{sun}_ (0.43%). The power law exponents that we derive for the two stars indicate a significantly weaker limb darkening than predicted by both 1D and 3D stellar atmosphere models. As this discrepancy is also observed on the near-infrared limb darkening profile of the Sun, an improvement of the calibration of stellar atmosphere models is clearly needed. The reported PIONIER visibility measurements of Alpha Cen A and B provide a robust basis to validate the future evolutions of these models.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A94
- Title:
- HD141569A system ALMA and NOEMA data cubes
- Short Name:
- J/A+A/635/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The study of gas-rich debris discs is fundamental to characterising the transition between protoplanetary discs and debris discs. Aims. We determine the physical parameters of the brightest gas-rich debris disc orbiting HD 141569A. We analyse images from the NOrthern Extended Millimeter Array (NOEMA) and the Atacama Large Millimeter/submillimeter Array (ALMA) in ^12^CO, ^13^CO J=2-1, and ^13^CO J=1-0 transitions. We incorporate ALMA archival data of the ^12^CO J=3-2 transition and present continuum maps at 0.87mm, 1.3mm, and 2.8mm. We use simple parametric laws with the Diskfit code and MCMC exploration to characterise the gas disc parameters and report a first attempt to characterise its chemical content with IRAM-30m. The continuum emission is equally shared between a compact (<50au) and a smooth, extended dust component (~350 au). Large millimetre grains seem to dominate the inner regions, while the dust spectral index is marginally larger in the outer region. The ^12^CO is optically thick, while ^13^CO is optically thin with tau_13CO_~0.15 (C^18^O is not detected). The ^13^CO surface density is constrained to be one order of magnitude smaller than around younger Herbig Ae stars, and we derive a gas mass M_12CO_=10^-1^M_{sun}_. We confirm the presence of a small CO cavity (R_CO_=17+/-3au), and find a possibly larger radius for the optically thin ^13^CO J=2-1 transition (35+/-5au). We show that the observed CO brightness asymmetry is coincident with the complex ring structures discovered with VLT/SPHERE in the inner 90au. The ^12^CO temperature T_0_(100au)~30K is lower than expected for a Herbig~A0 star, and could be indicative of subthermal excitation. With the largest amount of dust and gas among hybrid discs, HD141569A shows coincident characteristics of both protoplanetary discs (central regions), and debris discs at large distance. Together with its morphological characteristics and young age, it appears to be a good candidate to witness the transient phase of gas dissipation, with an apparently large gas-to-dust ratio (G/D>100) favouring a faster evolution of dust grains.
- ID:
- ivo://CDS.VizieR/J/A+A/654/A60
- Title:
- HD 22496 b ESPRESSO RVs
- Short Name:
- J/A+A/654/A60
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The ESPRESSO spectrograph is a new powerful tool developed to detect and characterize extrasolar planets. Its design allows an unprecedented radial velocity precision (down to a few tens of cm/s) and long-term thermomechanical stability. We present the first stand-alone detection of an extrasolar planet by blind radial velocity search using ESPRESSO; our aim is to show the power of the instrument in characterizing planetary signals at different periodicities in long observing time spans. We used 41 ESPRESSO measurements of HD 22496 obtained within a time span of 895 days with a median photon noise of 18cm/s. A radial velocity analysis was performed to test the presence of planets in the system and to account for the stellar activity of this K5-K7 main-sequence star. For benchmarking and comparison, we attempted the detection with 43 archive HARPS measurements and in this work we compare the results yielded by the two datasets. We also used four TESS sectors to search for transits. We find radial velocity variations compatible with a close-in planet with an orbital period of P=5.09071+/-0.00026 days when simultaneously accounting for the effects of stellar activity on longer timescales (Prot=34.99_-0.53_^+0.58^ days). We characterize the physical and orbital properties of the planet and find a minimum mass of 5.57_-0.68_^+0.73^M_{sun}_, right in the dichotomic regime between rocky and gaseous planets. Although not transiting according to TESS data, if aligned with the stellar spin axis, the absolute mass of the planet must be below 16M_{sun}_. We find no significant evidence for additional signals in the data with semi-amplitudes above 56cm/s at 95% confidence. With a modest set of radial velocity measurements, ESPRESSO is capable of detecting and characterizing low-mass planets and constraining the presence of planets in the habitable zone of K dwarfs down to the rocky-mass regime.
- ID:
- ivo://CDS.VizieR/J/ApJ/791/55
- Title:
- HD 189733b in transit light curve
- Short Name:
- J/ApJ/791/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report near-infrared spectroscopy of the gas giant planet HD 189733b in transit. We used the Hubble Space Telescope Wide Field Camera 3 (HST WFC3) with its G141 grism covering 1.1 {mu}m to 1.7 {mu}m and spatially scanned the image across the detector at 2''/s. When smoothed to 75 nm bins, the local maxima of the transit depths in the 1.15 {mu}m and 1.4 {mu}m water vapor features are, respectively, 83+/-53 ppm and 200+/-47 ppm greater than the local minimum at 1.3 {mu}m. We compare the WFC3 spectrum with the composite transit spectrum of HD 189733b assembled by Pont et al., extending from 0.3 {mu}m to 24 {mu}m. Although the water vapor features in the WFC3 spectrum are compatible with the model of non-absorbing, Rayleigh-scattering dust in the planetary atmosphere, we also re-interpret the available data with a clear planetary atmosphere. In the latter interpretation, the slope of increasing transit depth with shorter wavelengths from the near infrared, through the visible, and into the ultraviolet is caused by unocculted star spots, with a smaller contribution of Rayleigh scattering by molecular hydrogen in the planet's atmosphere. At relevant pressures along the terminator, our model planetary atmosphere's temperature is ~700 K, which is below the condensation temperatures of sodium- and potassium-bearing molecules, causing the broad wings of the spectral lines of Na I and K I at 0.589 {mu}m and 0.769 {mu}m to be weak.
- ID:
- ivo://CDS.VizieR/J/A+A/609/L5
- Title:
- HD147379 b velocity curve
- Short Name:
- J/A+A/609/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the first star discovered to host a planet detected by radial velocity (RV) observations obtained within the CARMENES survey for exoplanets around M dwarfs. HD 147379 (V=8.9mag, M=0.58+/-0.08M_{sun}_), a bright M0.0 V star at a distance of 10.7pc, is found to undergo periodic RV variations with a semi-amplitude of K=5.1+/-0.4m/s and a period of P=86.54+/-0.06d. The RV signal is found in our CARMENES data, which were taken between 2016 and 2017, and is supported by HIRES/Keck observations that were obtained since 2000. The RV variations are interpreted as resulting from a planet of minimum mass m_P_sini=25+/-2M_{Earth}_, 1.5 times the mass of Neptune, with an orbital semi-major axis a=0.32au and low eccentricity (e<0.13). HD 147379 b is orbiting inside the temperate zone around the star, where water could exist in liquid form. The RV time-series and various spectroscopic indicators show additional hints of variations at an approximate period of 21.1d (and its first harmonic), which we attribute to the rotation period of the star.
- ID:
- ivo://CDS.VizieR/J/A+A/637/A93
- Title:
- HD 79211 CARMENES radial velocities
- Short Name:
- J/A+A/637/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on radial velocity time series for two M0.0V stars, GJ 338 B and GJ 338 A, using the CARMENES spectrograph, complemented by ground-telescope photometry from Las Cumbres and Sierra Nevada observatories. We obtained 159 and 70 radial velocity measurements of GJ 338 B and A, respectively, with the CARMENES visible channel between 2016 January and 2018 October. We also compiled additional relative radial velocity measurements from the literature and a collection of astrometric data that cover 200yr of observations to solve for the binary orbit. We found dynamical masses of 0.64+/-0.07M_{sun}_ for GJ338B and 0.69+/-0.07M_{sun}_ for GJ338A. The CARMENES radial velocity periodograms show significant peaks at 16.61+/-0.04d (GJ 338 B) and 16.3+/-3.5d (GJ 338 A), which have counterparts at the same frequencies in CARMENES activity indicators and photometric light curves. We attribute these to stellar rotation. GJ 338 B shows two additional, significant signals at 8.27+/-0.01 and 24.45+/-0.02d, with no obvious counterparts in the stellar activity indices. The former is likely the first harmonic of the star's rotation, while we ascribe the latter to the existence of a super-Earth planet with a minimum mass of 10.27+/-1.47M_{Earth}_ orbiting GJ 338 B.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A157
- Title:
- HD 108236 CHEOPS light curves
- Short Name:
- J/A+A/646/A157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The detection of a super-Earth and three mini-Neptunes transiting the bright (V=9.2mag) star HD108236 (also known as TOI-1233) was recently reported on the basis of TESS and ground-based light curves. We perform a first characterisation of the HD108236 planetary system through high-precision CHEOPS photometry and improve the transit ephemerides and system parameters. We characterise the host star through spectroscopic analysis and derive the radius with the infrared flux method.We constrain the stellar mass and age by combining the results obtained from two sets of stellar evolutionary tracks. We analyse the available TESS light curves and one CHEOPS transit light curve for each known planet in the system. We find that HD108236 is a Sun-like star with R*=0.877+/-0.008R_{sun}_, M*=0.869^+0.050^_0.048_M_{sun}_, and an age of 6.7^+4.0^_5.1_Gyr. We report the serendipitous detection of an additional planet, HD108236 f, in one of the CHEOPS light curves. For this planet, the combined analysis of the TESS and CHEOPS light curves leads to a tentative orbital period of about 29.5days. From the light curve analysis, we obtain radii of 1.615+/-0.051, 2.071+/-0.052, 2.539^+0.062^_0.065_, 3.083+/-0.052, and 2.017^+0.052^+0.057_R_{Earth}_ for planets HD108236 b to HD108236 f, respectively. These values are in agreement with previous TESS-based estimates, but with an improved precision of about a factor of two. We perform a stability analysis of the system, concluding that the planetary orbits most likely have eccentricities smaller than 0.1. We also employ a planetary atmospheric evolution framework to constrain the masses of the five planets, concluding that HD108236 b and HD108236 c should have an Earth-like density, while the outer planets should host a low mean molecular weight envelope. The detection of the fifth planet makes HD108236 the third system brighter than V=10mag to host more than four transiting planets. The longer time span enables us to significantly improve the orbital ephemerides such that the uncertainty on the transit times will be of the order of minutes for the years to come. A comparison of the results obtained from the TESS and CHEOPS light curves indicates that for a V~9mag solar-like star and a transit signal of 500ppm, one CHEOPS transit light curve ensures the same level of photometric precision as eight TESS transits combined, although this conclusion depends on the length and position of the gaps in the light curve.
- ID:
- ivo://CDS.VizieR/J/A+A/603/L5
- Title:
- HD106315c I light curve
- Short Name:
- J/A+A/603/L5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Space-based transit surveys such as K2 and the Transiting Exoplanets Survey Satellite (TESS) allow the detection of small transiting planets with orbital periods greater than 10 days. Few of these warm Neptunes are currently known around stars bright enough to allow for detailed follow-up observations dedicated to their atmospheric characterization. The 21-day period and 3.95R_Earth_ planet HD106315c has been discovered by K2 based on the observation of two of its transits. We observed HD 106315 using the 1.2m Euler telescope equipped with the EulerCam camera on two occasions to confirm the transit using broadband photometry and refine the planetary period. Based on two observed transits of HD106315c, we detect its ~1mmag transit and obtain a precise measurement of the planetary ephemerides, which are critical for planning further follow-up observations. We used the attained precision together with the predicted yield from the TESS mission to evaluate the potential for ground-based confirmation of Neptune-sized planets found by TESS. We find that one-meter class telescopes on the ground equipped with precise photometers could substantially contribute to the follow-up of 162 TESS candidates orbiting stars with magnitudes of V<14. Of these candidates, 74 planets orbit stars with V<12 and 12 planets orbit V<10, which makes them high-priority objects for atmospheric characterization with high-end instrumentation.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A19
- Title:
- HD 117214 debris disk polarization images
- Short Name:
- J/A+A/635/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young stars with debris disks are the most promising targets for an exoplanet search because debris indicate a successful formation of planetary bodies. Debris disks can be shaped by planets into ring structures that give valuable indications on the presence and location of planets in the disk. We performed observations of the Sco-Cen F star HD 117214 to search for planetary companions and to characterize the debris disk structure. HD 117214 was observed with the SPHERE subsystems IRDIS, IFS, and ZIMPOL at optical and near-IR wavelengths using angular and polarimetric differential imaging techniques. This provided the first images of scattered light from the debris disk with the highest spatial resolution of 25mas and an inner working angle <0.1". With the observations with IRDIS and IFS we derived detection limits for substellar companions. The geometrical parameters of the detected disk were constrained by fitting 3D models for the scattering of an optically thin dust disk. Investigating the possible origin of the disk gap, we introduced putative planets therein and modeled the planet-disk and planet-planet dynamical interactions. The obtained planetary architectures were compared with the detection limit curves. The debris disk has an axisymmetric ring structure with a radius of 0.42(+/-0.01)" or ~45au and an inclination of 71(+/-2.5){deg} and exhibits a 0.4" (~40au) wide inner cavity. From the polarimetric data, we derive a polarized flux contrast for the disk of (Fpol)_disk_/F*=(3.1+/-1.2)x10^-4^ in the RI band. The fractional scattered polarized flux of the disk is eight times lower than the fractional IR flux excess. This ratio is similar to the one obtained for the debris disk HIP 79977, indicating that dust radiation properties are similar for these two disks. Inside the disk cavity we achieve high-sensitivity limits on planetary companions with a mass down to ~4M_J_ at projected radial separations between 0.2" and 0.4". We can exclude stellar companions at a radial separation larger than 75mas from the star.
