- ID:
- ivo://CDS.VizieR/J/A+A/586/A75
- Title:
- Simulations of hot gas planets atmospheres
- Short Name:
- J/A+A/586/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Absorption of high-energy radiation in planetary thermospheres is generally believed to lead to the formation of planetary winds. The resulting mass-loss rates can affect the evolution, particularly of small gas planets. We present 1D, spherically symmetric hydrodynamic simulations of the escaping atmospheres of 18 hot gas planets in the solar neighborhood. Our sample only includes strongly irradiated planets, whose expanded atmospheres may be detectable via transit spectroscopy using current instrumentation. The simulations were performed with the PLUTO-CLOUDY interface, which couples a detailed photoionization and plasma simulation code with a general MHD code. We study the thermospheric escape and derive improved estimates for the planetary mass-loss rates. Our simulations reproduce the temperature-pressure profile measured via sodium D absorption in HD 189733 b, but show still unexplained differences in the case of HD 209458 b. In contrast to general assumptions, we find that the gravitationally more tightly bound thermospheres of massive and compact planets, such as HAT-P-2 b are hydrodynamically stable. Compact planets dispose of the radiative energy input through hydrogen Ly alpha and free-free emission. Radiative cooling is also important in HD 189733 b, but it decreases toward smaller planets like GJ 436 b. Computing the planetary Ly alpha absorption and emission signals from the simulations, we find that the strong and cool winds of smaller planets mainly cause strong Ly alpha absorption but little emission. Compact and massive planets with hot, stable thermospheres cause small absorption signals but are strong Ly{alpha} emitters, possibly detectable with the current instrumentation. The absorption and emission signals provide a possible distinction between these two classes of thermospheres in hot gas planets. According to our results, WASP-80 and GJ 3470 are currently the most promising targets for observational follow-up aimed at detecting atmospheric Ly{alpha} absorption signals.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/210/20
- Title:
- Small Kepler planets radial velocities
- Short Name:
- J/ApJS/210/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g/cm3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than ~2 R_{oplus}_. Larger planets evidently contain a larger fraction of low-density material (H, He, and H_2_O).
- ID:
- ivo://CDS.VizieR/J/A+A/552/A78
- Title:
- Solar like stars radial velocities
- Short Name:
- J/A+A/552/A78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 1992 we began a precision radial velocity (RV) survey for planets around solar-like stars with the Coude Echelle Spectrograph and the Long Camera (CES LC) at the 1.4m telescope in La Silla (Chile). We have continued the survey with the upgraded CES Very Long Camera (VLC) and HARPS, both at the 3.6m telescope, until 2007. The observations for 31 stars cover a time span of up to 15 years and the RV precision permit a search for Jupiter analogues. We perform a joint analysis for variability, trends, periodicities, and Keplerian orbits and compute detection limits. Moreover, the HARPS RVs are analysed for correlations with activity indicators (CaII H&K and CCF shape). We achieve a long-term RV precision of 15m/s (CES+LC, 1992-1998), 9m/s (CES+VLC, 1999-2006), and 2.8m/s (HARPS, 2003-2009, including archive data), resp. This enables us to confirm the known planets around Iota Hor, HR 506, and HR 3259. A steady RV trend for Eps Ind A can be explained by a planetary companion. On the other hand, we find previously reported trends to be smaller for Beta Hyi and not present for Alp Men. The candidate planet Eps Eri b was not detected despite our better precision. Also the planet announced for HR 4523 cannot be confirmed. Long-term trends in several of our stars are compatible with known stellar companions. We provide a spectroscopic orbital solution for the binary HR 2400 and refined solutions for the planets around HR 506 and Iota Hor. For some other stars the variations could be attributed to stellar activity.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A175
- Title:
- Solar system analogs with HARPS
- Short Name:
- J/A+A/615/A175
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The assessment of the frequency of planetary systems reproducing the solar system's architecture is still an open problem in exoplanetary science. Detailed study of multiplicity and architecture is generally hampered by limitations in quality, temporal extension and observing strategy, causing difficulties in detecting low-mass inner planets in the presence of outer giant planets. We present the results of high-cadence and high-precision HARPS observations on 20 solar-type stars known to host a single long-period giant planet in order to search for additional inner companions and estimate the occurence rate f_p_ of scaled solar system analogues - in other words, systems featuring lower-mass inner planets in the presence of long-period giant planets. We carried out combined fits of our HARPS data with literature radial velocities using differential evolution MCMC to refine the literature orbital solutions and search for additional inner planets. We then derived the survey detection limits to provide preliminary estimates of f_p_. We generally find better constrained orbital parameters for the known planets than those found in the literature; significant updates can be especially appreciated on half of the selected planetary systems. While no additional inner planet is detected, we find evidence for previously unreported long-period massive companions in systems HD 50499 and HD 73267. We finally estimate the frequency of inner low mass (10-30M_{earth}_) planets in the presence of outer giant planets as f_p_<9.84% for P<150-days. Our preliminary estimate of f_p_ is significantly lower than the literature values for similarly defined mass and period ranges; the lack of inner candidate planets found in our sample can also be seen as evidence corroborating the inwards-migration formation model for super-Earths and mini-Neptunes. Our results also underline the need for high-cadence and high-precision followup observations as the key to precisely determine the occurence of solar system analogues.
- ID:
- ivo://CDS.VizieR/J/AJ/142/19
- Title:
- Speckle observations of KOI
- Short Name:
- J/AJ/142/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from a speckle imaging survey of stars classified as candidate exoplanet host stars discovered by the Kepler mission. We use speckle imaging to search for faint companions or closely aligned background stars that could contribute flux to the Kepler light curves of their brighter neighbors. Background stars are expected to contribute significantly to the pool of false positive candidate transiting exoplanets discovered by the Kepler mission, especially in the case that the faint neighbors are eclipsing binary stars. Here, we describe our Kepler follow-up observing program, the speckle imaging camera used, our data reduction, and astrometric and photometric performance. Kepler stars range from R=8 to 16 and our observations attempt to provide background non-detection limits 5-6mag fainter and binary separations of ~0.05-2.0-arcsec. We present data describing the relative brightness, separation, and position angles for secondary sources, as well as relative plate limits for non-detection of faint nearby stars around each of 156 target stars. Faint neighbors were found near 10 of the stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/188
- Title:
- Spectra of nearby late K and M Kepler stars
- Short Name:
- J/ApJ/779/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use moderate-resolution spectra of nearby late K and M dwarf stars with parallaxes and interferometrically determined radii to refine their effective temperatures, luminosities, and metallicities. We use these revised values to calibrate spectroscopic techniques to infer the fundamental parameters of more distant late-type dwarf stars. We demonstrate that, after masking out poorly modeled regions, the newest version of the PHOENIX atmosphere models accurately reproduce temperatures derived bolometrically. We apply methods to late-type hosts of transiting planet candidates in the Kepler field, and calculate effective temperature, radius, mass, and luminosity with typical errors of 57K, 7%, 11%, and 13%, respectively. We find systematic offsets between our values and those from previous analyses of the same stars, which we attribute to differences in atmospheric models utilized for each study. We investigate which of the planets in this sample are likely to orbit in the circumstellar habitable zone. We determine that four candidate planets (KOI 854.01, 1298.02, 1686.01, and 2992.01) are inside of or within 1{sigma} of a conservative definition of the habitable zone, but that several planets identified by previous analyses are not (e.g., KOI 1422.02 and KOI 2626.01). Only one of the four habitable-zone planets is Earth sized, suggesting a downward revision in the occurrence of such planets around M dwarfs. These findings highlight the importance of measuring accurate stellar parameters when deriving parameters of their orbiting planets.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/43
- Title:
- Spectroscopic [Fe/H] of Kepler stars
- Short Name:
- J/ApJ/770/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been shown that F, G, and early K dwarf hosts of Neptune-sized planets are not preferentially metal-rich. However, it is less clear whether the same holds for late K and M dwarf planet hosts. We report metallicities of Kepler targets and candidate transiting planet hosts with effective temperatures below 4500K. We use new metallicity calibrations to determine [Fe/H] from visible and near-infrared spectra. We find that the metallicity distribution of late K and M dwarfs monitored by Kepler is consistent with that of the solar neighborhood. Further, we show that hosts of Earth- to Neptune-sized planets have metallicities consistent with those lacking detected planets and rule out a previously claimed 0.2dex offset between the two distributions at 6{sigma} confidence. We also demonstrate that the metallicities of late K and M dwarfs hosting multiple detected planets are consistent with those lacking detected planets. Our results indicate that multiple terrestrial and Neptune-sized planets can form around late K and M dwarfs with metallicities as low as 0.25 solar. The presence of Neptune-sized planets orbiting such low-metallicity M dwarfs suggests that accreting planets collect most or all of the solids from the disk and that the potential cores of giant planets can readily form around M dwarfs. The paucity of giant planets around M dwarfs compared to solar-type stars must be due to relatively rapid disk evaporation or a slower rate of planet accretion, rather than insufficient solids to form a core.
- ID:
- ivo://CDS.VizieR/J/A+A/487/373
- Title:
- Spectroscopic parameters of 451 HARPS-GTO stars
- Short Name:
- J/A+A/487/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To understand the formation and evolution of solar-type stars in the solar neighborhood, we need to measure their stellar parameters to high accuracy. We present a catalogue of accurate stellar parameters for 451 stars that represent the HARPS Guaranteed Time Observations (GTO) "high precision" sample. Spectroscopic stellar parameters were measured using high signal-to-noise (S/N) spectra acquired with the HARPS spectrograph. The spectroscopic analysis was completed assuming LTE with a grid of Kurucz atmosphere models and the recent ARES code for measuring line equivalent widths. We show that our results agree well with those ones presented in the literature (for stars in common). We present a useful calibration for the effective temperature as a function of the index color B-V and [Fe/H]. We use our results to study the metallicity-planet correlation, namely for very low mass planets. The results presented here suggest that in contrast to their jovian counterparts, Neptune-like planets do not form preferentially around metal-rich stars. The ratio of Jupiter-to-Neptune is also an increasing function of stellar metallicity. These results are discussed in the context of the core-accretion model for planet formation.
- ID:
- ivo://CDS.VizieR/J/AJ/150/168
- Title:
- Spectroscopy and photometry for HAT-P-50--HAT-P-53
- Short Name:
- J/AJ/150/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery and characterization of four transiting exoplanets by the HATNet survey. The planet HAT-P-50b has a mass of 1.35M_J_ and radius of 1.29R_J_, and orbits a bright (V=11.8mag) M=1.27M_{sun}_, R=1.70R_{sun}_ star every P=3.1220days. The planet HAT-P-51b has a mass of 0.31M_J_ and radius of 1.29R_J_, and orbits a V=13.4mag, M=0.98M_{sun}_, R=1.04R_{sun}_ star with a period of P=4.2180days. The planet HAT-P-52b has a mass of 0.82M_J_ and radius of 1.01R_J_, and orbits a V=14.1mag, M=0.89M_{sun}_, R=0.89R_{sun}_ star with a period of P=2.7536days. The planet HAT-P-53b has a mass of 1.48M_J_ and radius of 1.32R_J_, and orbits a V=13.7mag, M=1.09M_{sun}_, R=1.21R_{sun}_ star with a period of P=1.9616days. All four planets are consistent with having circular orbits and have masses and radii measured to better than 10% precision. The low stellar jitter and favorable R_p_/R_{star}_ ratio for HAT-P-51 make it a promising target for measuring the Rossiter-McLaughlin effect for a Saturn-mass planet.
- ID:
- ivo://CDS.VizieR/J/AJ/152/88
- Title:
- Spectroscopy and photometry of HATS-11 and HATS-12
- Short Name:
- J/AJ/152/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two transiting extrasolar planets from the HATSouth survey. HATS-11, a V=14.1 G0-star shows a periodic 12.9mmag dip in its light curve every 3.6192days and a radial velocity variation consistent with a Keplerian orbit. HATS-11 has a mass of 1.000+/-0.060M_{Sun}_, a radius of 1.444+/-0.057R_{Sun}_ and an effective temperature of 6060+/-150K, while its companion is a 0.85+/-0.12M_J_, 1.510+/-0.078R_J_ planet in a circular orbit. HATS-12 shows a periodic 5.1mmag flux decrease every 3.1428days and Keplerian radial velocities variations around a V=12.8 F-star. HATS-12 has a mass of 1.489+/-0.071M_{Sun}_, a radius of 2.21+/-0.21R_{Sun}_, and an effective temperature of 6408+/-75K. For HATS-12b, our measurements indicate that this is a 2.38+/-0.11M_J_, 1.35+/-0.17R_J_ planet in a circular orbit. Both host stars show subsolar metallicities of -0.390+/-0.060dex and -0.100+/-0.040dex, respectively, and are (slightly) evolved stars. In fact, HATS-11 is among the most metal-poor and, HATS-12, with a logg_*_ of 3.923+/-0.065, is among the most evolved stars hosting a hot-Jupiter planet. Importantly, HATS-11 and HATS-12 have been observed in long cadence by Kepler as part of K2 campaign 7 (EPIC216414930 and EPIC218131080 respectively).
