- ID:
- ivo://CDS.VizieR/J/A+A/624/A118
- Title:
- Fitted orbits and parameters of 51 Eridani b
- Short Name:
- J/A+A/624/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 51 Eridani observations were performed with the VLT exoplanet imager SPHERE for 3 years in order to monitor the orbital motion of the known giant planet and refine its orbital parameters. We carried out an orbital analysis using three complementary approaches (LSMC, MCMC, Bayesian rejection sampling) and found broadly similar results. The data suggest a period of 23-49yr (i.e. semi-major axis of 10-16au), an inclination of 126-147{deg}, an eccentricity of 0.30-0.55, and an argument at periastron of 57-121{deg} (mod 180{deg}). The time at periastron and the longitude of node exhibit bimodal distributions.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/158/63
- Title:
- Five new transiting hot Jupiters:HATS-54b-HATS-58b
- Short Name:
- J/AJ/158/63
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery by the HATSouth project of five new transiting hot Jupiters (HATS-54b through HATS-58Ab). HATS-54b, HATS-55b, and HATS-58Ab are prototypical short-period (P=2.5-4.2 days, R_p_~1.1-1.2 R_J_) hot Jupiters that span effective temperatures from 1350 to 1750 K, putting them in the proposed region of maximum radius inflation efficiency. The HATS-58 system is composed of two stars, HATS-58A and HATS-58B, which are detected thanks to Gaia DR2 data and which we account for in the joint modeling of the available data-with this, we are led to conclude that the hot Jupiter orbits the brighter HATS-58A star. HATS-57b is a short-period (2.35 day), massive (3.15 M_J_), 1.14 R_J_, dense (2.65+/-0.21 g/cm^3^) hot Jupiter orbiting a very active star (2% peak-to-peak flux variability). Finally, HATS-56b is a short-period (4.32 day), highly inflated hot Jupiter (1.7 R_J_, 0.6 M_J_), which is an excellent target for future atmospheric follow-up, especially considering the relatively bright nature (V=11.6) of its F dwarf host star. This latter exoplanet has another very interesting feature: the radial velocities show a significant quadratic trend. If we interpret this quadratic trend as arising from the pull of an additional planet in the system, we obtain a period of P_c_=815_-143_^+253^ days for the possible planet HATS-56c, and a minimum mass of M_c_sini_c_=5.11+/-0.94 M_J_. The candidate planet HATS-56c would have a zero-albedo equilibrium temperature of T_eq_=332+/-50 K, and thus would be orbiting close to the habitable zone of HATS-56. Further radial-velocity follow-up, especially over the next two years, is needed to confirm the nature of HATS-56c.
- ID:
- ivo://CDS.VizieR/J/AJ/159/100
- Title:
- Flux & RVs of the dwarf G9-40 with K2 & HPF
- Short Name:
- J/AJ/159/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We validate the discovery of a 2-Earth-radii sub-Neptune-sized planet around the nearby high-proper-motion M2.5 dwarf G9-40 (EPIC212048748), using high-precision, near-infrared (NIR) radial velocity (RV) observations with the Habitable-zone Planet Finder (HPF), precision diffuser-assisted ground-based photometry with a custom narrowband photometric filter, and adaptive optics imaging. At a distance of d=27.9pc, G9-40b is the second-closest transiting planet discovered by K2 to date. The planet's large transit depth (~3500ppm), combined with the proximity and brightness of the host star at NIR wavelengths (J=10, K=9.2), makes G9-40b one of the most favorable sub-Neptune-sized planets orbiting an M dwarf for transmission spectroscopy with James Webb Space Telescope, ARIEL, and the upcoming Extremely Large Telescopes. The star is relatively inactive with a rotation period of ~29days determined from the K2 photometry. To estimate spectroscopic stellar parameters, we describe our implementation of an empirical spectral-matching algorithm using the high-resolution NIR HPF spectra. Using this algorithm, we obtain an effective temperature of Teff=3404{+/-}73K and metallicity of [Fe/H]=-0.08{+/-}0.13. Our RVs, when coupled with the orbital parameters derived from the transit photometry, exclude planet masses above 11.7M{Earth} with 99.7% confidence assuming a circular orbit. From its radius, we predict a mass of M=5.0_-1.9_^+3.8^M_{Earth}_ and an RV semiamplitude of K=4.1_-1.6_^+3.1^m/s, making its mass measurable with current RV facilities. We urge further RV follow-up observations to precisely measure its mass, to enable precise transmission spectroscopic measurements in the future.
- ID:
- ivo://CDS.VizieR/J/A+A/646/A131
- Title:
- Four Jovian planets RV and activity indexes
- Short Name:
- J/A+A/646/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of planetary companions orbiting four low-luminosity giant stars with M* between 1.04 and 1.39M_{sun}_. All four host stars have been independently observed by the EXoPlanets aRound Evolved StarS (EXPRESS) program and the Pan-Pacific Planet Search (PPPS). The companion signals were revealed by multi-epoch precision radial velocities obtained in nearly a decade. The planetary companions exhibit orbital periods between ~1.2 and 7.1 years, minimum masses of m_p_*sini~1.8-3.7M_Jup_, and eccentricities between 0.08 and 0.42. With these four new systems, we have detected planetary companions to 11 out of the 37 giant stars that are common targets in the EXPRESS and PPPS. After excluding four compact binaries from the common sample, we obtained a fraction of giant planets (m_p_~1-2M_Jup_) orbiting within 5AU from their parent star of f=33.3^+9.0^_-7.1_%. This fraction is slightly higher than but consistent at the 1{sigma} level with previous results obtained by different radial velocity surveys. Finally, this value is substantially higher than the fraction predicted by planet formation models of gas giants around stars more massive than the Sun.
- ID:
- ivo://CDS.VizieR/J/AJ/160/138
- Title:
- 68 Gaia DR2 ultra-short-period planet host stars
- Short Name:
- J/AJ/160/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been unambiguously shown both in individual systems and at the population level that hot Jupiters experience tidal inspiral before the end of their host stars main-sequence lifetimes. Ultra-short-period (USP) planets have orbital periods P<1 day, rocky compositions, and are expected to experience tidal decay on similar timescales to hot Jupiters if the efficiency of tidal dissipation inside their host stars parameterized as Q_*_' is independent of P and/or secondary mass M_p_. Any difference between the two classes of systems would reveal that a model with constant Q_*_' is insufficient. If USP planets experience tidal inspiral, then USP planet systems will be relatively young compared to similar stars without USP planets. Because it is a proxy for relative age, we calculate the Galactic velocity dispersions of USP planet candidate host and non-host stars using data from Gaia Data Release 2 supplemented with ground-based radial velocities. We find that main-sequence USP planet candidate host stars have kinematics consistent with similar stars in the Kepler field without observed USP planets. This indicates that USP planet hosts have similar ages to field stars and that USP planets do not experience tidal inspiral during the main-sequence lifetimes of their host stars. The survival of USP planets requires that Q_*_'>~10^7^ at P~0.7day and M_p_~2.6M{Earth}. This result demands that Q_*_' depend on the orbital period and/or mass of the secondary in the range 0.5day<~P<~5days and 1M{Earth}<~M_p_<~1000M{sun}.
- ID:
- ivo://CDS.VizieR/J/AJ/160/108
- Title:
- Gaia-Kepler stellar properties catalog. II. Planets
- Short Name:
- J/AJ/160/108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Studies of exoplanet demographics require large samples and precise constraints on exoplanet host stars. Using the homogeneous Kepler stellar properties derived using the Gaia Data Release 2 by Berger et al., we recompute Kepler planet radii and incident fluxes and investigate their distributions with stellar mass and age. We measure the stellar mass dependence of the planet radius valley to be dlogR_p/d_logM_{star}_=0.26_-0.16_^+0.21^, consistent with the slope predicted by a planet mass dependence on stellar mass (0.24-0.35) and core-powered mass loss (0.33). We also find the first evidence of a stellar age dependence of the planet populations straddling the radius valley. Specifically, we determine that the fraction of super-Earths (1-1.8{R_{Earth}_) to sub-Neptunes (1.8-3.5R_{Earth}_) increases from 0.61{+/-}0.09 at young ages (<1Gyr) to 1.00{+/-}0.10 at old ages (>1Gyr), consistent with the prediction by core-powered mass loss that the mechanism shaping the radius valley operates over Gyr timescales. Additionally, we find a tentative decrease in the radii of relatively cool (Fp<150{F}_{Earth}_) sub-Neptunes over Gyr timescales, which suggests that these planets may possess H/He envelopes instead of higher mean molecular weight atmospheres. We confirm the existence of planets within the hot sub-Neptunian "desert" (2.2R_{Earth}_<Rp<3.8R_{Earth}_, Fp>650F_{Earth}_) and show that these planets are preferentially orbiting more evolved stars compared to other planets at similar incident fluxes. In addition, we identify candidates for cool (Fp<20F_{Earth}_) inflated Jupiters, present a revised list of habitable zone candidates, and find that the ages of single and multiple transiting planet systems are statistically indistinguishable.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A188
- Title:
- G 264-012 and Gl 393 radial velocity curves
- Short Name:
- J/A+A/650/A188
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We report the discovery of two planetary systems, namely G 264-012, an M4.0 dwarf with two terrestrial planets (M_b_sini=2.50^+0.29^_-0.30_M_{sun}_ and M_c_sini=3.75^+0.48^_-0.47_M_{sun}_), and Gl 393, a bright M2.0 dwarf with one terrestrial planet (M_b_sini=1.71+/-0.24M_{sun}_). Although both stars were proposed to belong to young stellar kinematic groups, we estimate their ages to be older than about 700Ma. The two planets around G 264-012 were discovered using only radial-velocity (RV) data from the CARMENES exoplanet survey, with estimated orbital periods of 2.30d and 8.05d, respectively. Photometric monitoring and analysis of activity indicators reveal a third signal present in the RV measurements, at about 100d, caused by stellar rotation. The planet Gl 393b was discovered in the RV data from the HARPS, CARMENES, and HIRES instruments. Its identification was only possible after modelling, with a Gaussian process (GP), the variability produced by the magnetic activity of the star. For the earliest observations, this variability produced a forest of peaks in the periodogram of the RVs at around the 34d rotation period determined from Kepler data, which disappeared in the latest epochs. After correcting for them with this GP model, a significant signal showed at a period of 7.03d. No significant signals in any of our spectral activity indicators or contemporaneous photometry were found at any of the planetary periods. Given the orbital and stellar properties, the equilibrium temperatures of the three planets are all higher than that for Earth. Current planet formation theories suggest that these two systems represent a common type of architecture. This is consistent with formation following the core accretion paradigm.
- ID:
- ivo://CDS.VizieR/J/AJ/162/57
- Title:
- g- and Ks-band flux of K2-22 with LBT
- Short Name:
- J/AJ/162/57
- Date:
- 14 Mar 2022 06:59:12
- Publisher:
- CDS
- Description:
- The disintegrating planet candidate K2-22b shows periodic and stochastic transits best explained by an escaping debris cloud. However, the mechanism that creates the debris cloud is unknown. The grain size of the debris as well as its sublimation rate can be helpful in understanding the environment that disintegrates the planet. Here, we present simultaneous photometry with the g band at 0.48{mu}m and KS band at 2.1{mu}m using the Large Binocular Telescope. During an event with very low dust activity, we put a new upper limit on the size of the planet of 0.71R{Earth} or 4500km. We also detected a medium depth transit that can be used to constrain the dust particle sizes. We find that the median particle size must be larger than about 0.5-1.0{mu}m, depending on the composition of the debris. This leads to a high mass-loss rate of about 3x108kg/s, which is consistent with hydrodynamic escape models. If they are produced by some alternate mechanism such as explosive volcanism, it would require extraordinary geological activity. Combining our upper limits on the planet size with the high mass-loss rate, we find a lifetime of the planet of less than 370Myr. This drops to just 21Myr when adopting the 0.02M{Earth} mass predicted from hydrodynamical models.
- ID:
- ivo://CDS.VizieR/J/AJ/155/226
- Title:
- Gemini Planet Imager spectra of HR 8799 c/d/e
- Short Name:
- J/AJ/155/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore Karhunen Loeve Image Projection (KLIP) forward modeling spectral extraction on Gemini Planet Imager coronagraphic data of HR 8799, using PyKLIP, and show algorithm stability with varying KLIP parameters. We report new and re-reduced spectrophotometry of HR 8799 c, d, and e in the H and K bands. We discuss a strategy for choosing optimal KLIP PSF subtraction parameters by injecting simulated sources and recovering them over a range of parameters. The K1/K2 spectra for HR 8799 c and d are similar to previously published results from the same data set. We also present a K-band spectrum of HR 8799 e for the first time and show that our H-band spectra agree well with previously published spectra from the VLT/SPHERE instrument. We show that HR 8799 c and d show significant differences in their H and K spectra, but do not find any conclusive differences between d and e, nor between c and e, likely due to large error bars in the recovered spectrum of e. Compared to M-, L-, and T-type field brown dwarfs, all three planets are most consistent with mid- and late-L spectral types. All objects are consistent with low gravity, but a lack of standard spectra for low gravity limit the ability to fit the best spectral type. We discuss how dedicated modeling efforts can better fit HR 8799 planets' near-IR flux, as well as how differences between the properties of these planets can be further explored.
- ID:
- ivo://CDS.VizieR/J/A+A/659/L4
- Title:
- Geometric albedo of HD 209458 b
- Short Name:
- J/A+A/659/L4
- Date:
- 02 Mar 2022 07:55:13
- Publisher:
- CDS
- Description:
- We report the detection of the secondary eclipse of the hot Jupiter HD 209458 b in optical/visible light using the CHEOPS space telescope. Our measurement of 20.4^+3.2^_3.3_ parts per million (ppm) translates into a geometric albedo of Ag=0.096+/-0.016. The previously estimated dayside temperature of about 1500K implies that our geometric albedo measurement consists predominantly of reflected starlight and is largely uncontaminated by thermal emission. This makes the present result one of the most robust measurements of Ag for any exoplanet, critical for understanding the atmosphere. Our calculations of the bandpass-integrated geometric albedo demonstrate that the measured value of Ag is consistent with a cloud-free atmosphere, where starlight is reflected via Rayleigh scattering by hydrogen molecules, with water and sodium abundances consistent with stellar metallicity. We predict that the bandpass-integrated TESS geometric albedo is too faint to detect and that a phase curve of HD 209458 b observed by CHEOPS would have a distinct shape associated with Rayleigh scattering if the atmosphere is indeed cloud-free.
