- ID:
- ivo://CDS.VizieR/J/other/NatAs/5.775
- Title:
- nu2 Lupi CHEOPS light curves
- Short Name:
- J/other/NatAs/5.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanets transiting bright nearby stars are key objects for advancing our knowledge of planetary formation and evolution. The wealth of photons from the host star gives detailed access to the atmospheric, interior and orbital properties of the planetary companions. nu^2^ Lupi (HD 136352) is a naked-eye (V=5.78) Sun-like star that was discovered to host three low-mass planets with orbital periods of 11.6, 27.6 and 107.6d via radial-velocity monitoring. The two inner planets (b and c) were recently found to transit2, prompting a photometric follow-up by the brand new Characterising Exoplanets Satellite (CHEOPS). Here, we report that the outer planet d is also transiting, and measure its radius and mass to be 2.56+/-0.09R_{Earth}_ and 8.82+/-0.94M_{Earth}_, respectively. With its bright Sun-like star, long period and mild irradiation (~5.7 times the irradiation of Earth), nu^2^ Lupi d unlocks a completely new region in the parameter space of exoplanets amenable to detailed characterization. We refine the properties of all three planets: planet b probably has a rocky mostly dry composition, while planets c and d seem to have retained small hydrogen-helium envelopes and a possibly large water fraction. This diversity of planetary compositions makes the nu^2^ Lupi system an excellent laboratory for testing formation and evolution models of low-mass planets.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/890/23
- Title:
- NUV and FUV measurements of planet host stars
- Short Name:
- J/ApJ/890/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search for evidence of the cause of the exoplanet radius gap, i.e., the dearth of planets with radii near 1.8R_{Earth}_. If the cause were photoevaporation, the radius gap should trend with proxies for the early-life high-energy emission of the planet-hosting stars. If, alternatively, the cause were core-powered mass loss, no such trends should exist. Critically, spurious trends between the radius gap and stellar properties arise from an underlying correlation with instellation. After accounting for this underlying correlation, we find that no trends remain between the radius gap and stellar mass or present-day stellar activity as measured by near-UV emission. We dismiss the nondetection of a radius gap trend with near-UV emission because present-day near-UV emission is unlikely to trace early-life high-energy emission, but we provide a catalog of Galaxy Evolution Explorer near-UV and far-UV emission measurements for general use. We interpret the nondetection of a radius gap trend with stellar mass by simulating photoevaporation with mass-dependent evolution of stellar high-energy emission. The simulation produces an undetectable trend between the radius gap and stellar mass under realistic sources of error. We conclude that no evidence, from this analysis or others in the literature, currently exists that clearly favors either photoevaporation or core-powered mass loss as the primary cause of the exoplanet radius gap. However, repeating this analysis once the body of well-characterized <4R_{Earth}_ planets has roughly doubled could confirm or rule out photoevaporation.
- ID:
- ivo://CDS.VizieR/J/AJ/155/177
- Title:
- Obliquities of planetary & eclipsing binary systems
- Short Name:
- J/AJ/155/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The light curve of an eclipsing system shows anomalies whenever the eclipsing body passes in front of active regions on the eclipsed star. In some cases, the pattern of anomalies can be used to determine the obliquity {Psi} of the eclipsed star. Here we present a method for detecting and analyzing these patterns, based on a statistical test for correlations between the anomalies observed in a sequence of eclipses. Compared to previous methods, ours makes fewer assumptions and is easier to automate. We apply it to a sample of 64 stars with transiting planets and 24 eclipsing binaries for which precise space-based data are available, and for which there was either some indication of flux anomalies or a previously reported obliquity measurement. We were able to determine obliquities for 10 stars with hot Jupiters. In particular we found {Psi}~<10{deg} for Kepler-45, which is only the second M dwarf with a measured obliquity. The other eight cases are G and K stars with low obliquities. Among the eclipsing binaries, we were able to determine obliquities in eight cases, all of which are consistent with zero. Our results also reveal some common patterns of stellar activity for magnetically active G and K stars, including persistently active longitudes.
- ID:
- ivo://CDS.VizieR/J/AJ/161/164
- Title:
- Observation of 186 TESS stars with NESSI (WYIN)
- Short Name:
- J/AJ/161/164
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We present high-resolution speckle interferometric imaging observations of TESS exoplanet host stars using the NN-EXPLORE Exoplanet and Stellar Speckle Imager instrument at the 3.5m WIYN telescope. Eight TESS objects of interest that were originally discovered by Kepler were previously observed using the Differential Speckle Survey Instrument. Speckle observations of 186 TESS stars were carried out, and 45 (24%) likely bound companions were detected. This is approximately the number of companions we would expect to observe given the established 46% binarity rate in exoplanet host stars. For the detected binaries, the distribution of stellar mass ratio is consistent with that of the standard Raghavan distribution and may show a decrease in high-q systems as the binary separation increases. The distribution of binary orbital periods, however, is not consistent with the standard Ragahavan model, and our observations support the premise that exoplanet-hosting stars with binary companions have, in general, wider orbital separations than field binaries. We find that exoplanet-hosting binary star systems show a distribution peaking near 100 au, higher than the 40-50au peak that is observed for field binaries. This fact led to earlier suggestions that planet formation is suppressed in close binaries.
- ID:
- ivo://CDS.VizieR/J/AJ/159/255
- Title:
- Observation & radial velocity of WASP-150 & WASP-176
- Short Name:
- J/AJ/159/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of two transiting exoplanets from the Wide Angle Search for Planets (WASP) survey, WASP-150b and WASP-176b. WASP-150b is an eccentric (e=0.38) hot Jupiter on a 5.6day orbit around a V=12.03, F8 main-sequence host. The host star has a mass and radius of 1.4M_{sun}_ and 1.7R_{sun}_ respectively. WASP-150b has a mass and radius of 8.5M_J_ and 1.1R_J_, leading to a large planetary bulk density of 6.4{rho}_J_. WASP-150b is found to be ~3Gyr old, well below its circularization timescale, supporting the eccentric nature of the planet. WASP-176b is a hot Jupiter planet on a 3.9day orbit around a V=12.01, F9 sub-giant host. The host star has a mass and radius of 1.3M{sun} and 1.9R{sun}. WASP-176b has a mass and radius of 0.86M_J_ and 1.5R_J_, respectively, leading to a planetary bulk density of 0.23{rho}_J_.
- ID:
- ivo://CDS.VizieR/J/AJ/157/235
- Title:
- Observations of the Kepler field with TESS
- Short Name:
- J/AJ/157/235
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the ability of the Transiting Exoplanet Survey Satellite (TESS) to detect and improve our understanding of planetary systems in the Kepler field. By modeling the expected transits of all confirmed and candidate planets detected by Kepler as expected to be observed by TESS, we provide a probabilistic forecast of the detection of each Kepler planet in TESS data. We find that TESS has a greater than 50% chance of detecting 260 of these planets at the 3{sigma} level in one sector of observations and an additional 120 planets in two sectors. Most of these are large planets in short orbits around their host stars, although a small number of rocky planets are expected to be recovered. Most of these systems have only one known transiting planet; in only ~5% of known multiply transiting systems do we anticipate more than one planet to be recovered. When these planets are recovered, we expect TESS to be a powerful tool to characterize transit timing variations. Using Kepler-88 (KOI-142) as an example, we show that TESS will improve measurements of planet-star mass ratios and orbital parameters, and significantly reduce the transit timing uncertainty in future years. Because TESS will be most sensitive to hot Jupiters, we research whether TESS will be able to detect tidal orbital decay in these systems. We find two confirmed planetary systems (Kepler-2 b and Kepler-13 b) and five candidate systems that will be good candidates to detect tidal decay.
- ID:
- ivo://CDS.VizieR/J/AJ/159/267
- Title:
- Observations & radial velocity of HATS-71b
- Short Name:
- J/AJ/159/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HATS-71b, a transiting gas giant planet on a P=3.7955day orbit around a G=15.35mag M3 dwarf star. HATS-71 is the coolest M dwarf star known to host a hot Jupiter. The loss of light during transits is 4.7%, more than in any other confirmed transiting planet system. The planet was identified as a candidate by the ground-based HATSouth transit survey. It was confirmed using ground-based photometry, spectroscopy, and imaging, as well as space-based photometry from the NASA Transiting Exoplanet Survey Satellite mission (TIC234523599). Combining all of these data, and utilizing Gaia DR2, we find that the planet has a radius of 1.024{+/-}0.018R_J_ and mass of 0.37{+/-}0.24M_J_ (95% confidence upper limit of <0.80M_J_), while the star has a mass of 0.4861{+/-}0.0060M_{sun}_ and a radius of 0.4783{+/-}0.0060R_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/155/205
- Title:
- Occurrence rates for Q1-Q16 KOI catalog planet cand.
- Short Name:
- J/AJ/155/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new framework to characterize the occurrence rates of planet candidates identified by Kepler based on hierarchical Bayesian modeling, approximate Bayesian computing (ABC), and sequential importance sampling. For this study, we adopt a simple 2D grid in planet radius and orbital period as our model and apply our algorithm to estimate occurrence rates for Q1-Q16 planet candidates orbiting solar-type stars. We arrive at significantly increased planet occurrence rates for small planet candidates (R_p_<1.25 R_{Earth}_) at larger orbital periods (P>80 day) compared to the rates estimated by the more common inverse detection efficiency method (IDEM). Our improved methodology estimates that the occurrence rate density of small planet candidates in the habitable zone of solar-type stars is 1.6_-0.5_^+1.2^ per factor of 2 in planet radius and orbital period. Additionally, we observe a local minimum in the occurrence rate for strong planet candidates marginalized over orbital period between 1.5 and 2 R_{Earth}_ that is consistent with previous studies. For future improvements, the forward modeling approach of ABC is ideally suited to incorporating multiple populations, such as planets, astrophysical false positives, and pipeline false alarms, to provide accurate planet occurrence rates and uncertainties. Furthermore, ABC provides a practical statistical framework for answering complex questions (e.g., frequency of different planetary architectures) and providing sound uncertainties, even in the face of complex selection effects, observational biases, and follow-up strategies. In summary, ABC offers a powerful tool for accurately characterizing a wide variety of astrophysical populations.
- ID:
- ivo://CDS.VizieR/J/AJ/162/216
- Title:
- Occurrence rates for systems with a Venus-like planet
- Short Name:
- J/AJ/162/216
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- Population studies of Kepler's multiplanet systems have revealed a surprising degree of structure in their underlying architectures. Information from a detected transiting planet can be combined with a population model to make predictions about the presence and properties of additional planets in the system. Using a statistical model for the distribution of planetary systems, we compute the conditional occurrence of planets as a function of the period and radius of Kepler-detectable planets. About half (0.52{+/-}0.03) of the time, the detected planet is not the planet with the largest semi-amplitude (K) in the system, so efforts to measure the mass of the transiting planet with radial velocity (RV) follow up will have to contend with additional planetary signals in the data. We simulate RV observations to show that assuming a single-planet model to measure the K of the transiting planet often requires significantly more observations than in the ideal case with no additional planets, due to systematic errors from unseen planet companions. Our results show that planets around 10 day periods with K close to the single-measurement RV precision ({sigma}1,obs) typically require ~100 observations to measure their K to within 20% error. For a next generation RV instrument achieving {sigma}1,obs =10cm/s, about ~200 (600) observations are needed to measure the K of a transiting Venus in a Kepler-like system to better than 20% (10%) error, which is ~2.3 times as many as would be necessary for a Venus without any planetary companions.
- ID:
- ivo://CDS.VizieR/J/AJ/158/109
- Title:
- Occurrence rates of planets orbiting FGK stars
- Short Name:
- J/AJ/158/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We characterize the occurrence rate of planets, ranging in size from 0.5 to 16 R_{Earth}_, orbiting FGK stars with orbital periods from 0.5 to 500 days. Our analysis is based on results from the "DR25" catalog of planet candidates produced by NASA's Kepler mission and stellar radii from Gaia "DR2" (Cat. I/345). We incorporate additional Kepler data products to accurately characterize the efficiency of planets being recognized as "threshold crossing events" by Kepler's Transiting Planet Search pipeline and labeled as planet candidates by the robovetter. Using a hierarchical Bayesian model, we derive planet occurrence rates for a wide range of planet sizes and orbital periods. For planets with sizes 0.75-1.5 R_{Earth}_ and orbital periods of 237-500 days, we find a rate of planets per FGK star of <0.27 (84.13th percentile). While the true rate of such planets could be lower by a factor of ~2 (primarily due to potential contamination of planet candidates by false alarms), the upper limits on the occurrence rate of such planets are robust to ~10%. We recommend that mission concepts aiming to characterize potentially rocky planets in or near the habitable zone of Sun-like stars prepare compelling science programs that would be robust for a true rate in the range f_R,P_=0.03-0.40 for 0.75-1.5 R_{Earth}_ planets with orbital periods in 237-500 days, or a differential rate of {Gamma}_{Earth}_=(d^2^f)/[d(lnP)d(lnR_p_)]=0.06-0.76.
