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Start Over Subject exoplanets Content Level Research
331. Radial velocity measurements for 7 stars
ID:
ivo://CDS.VizieR/J/A+A/625/A71
Title:
Radial velocity measurements for 7 stars
Short Name:
J/A+A/625/A71
Date:
21 Oct 2021
Publisher:
CDS
Description:
Since 1998, a planet-search around main sequence stars within 50pc in the southern hemisphere has been underway with the CORALIE spectrograph at La Silla Observatory. With an observing time span of more than 20 years, the CORALIE survey is able to detect long-term trends in data with masses and separations large enough to select ideal targets for direct imaging. Detecting these giant companion candidates will allow us to start bridging the gap between radial-velocity-detected exoplanets and directly imaged planets and brown dwarfs. Long-term precise Doppler measurements with the CORALIE spectrograph reveal radial-velocity signatures of massive planetary companions and brown dwarfs on long-period orbits. In this paper we report the discovery of new companions orbiting HD 181234, HD 13724, HD 25015, HD 92987 and HD 50499. We also report updated orbital parameters for HD 50499b, HD 92788b and HD 98649b. In addition, we confirm the recent detection of HD 92788c. The newly reported companions span a period range of 15.6 to 40.4 years and a mass domain of 2.93 to 26.77 MJup, the latter of which straddles the nominal boundary between planets and brown dwarfs. We report the detection of five new companions and updated parameters of four known extrasolar planets. We identify at least some of these companions to be promising candidates for imaging and further characterisation.
332. Radial velocity measurements of K2-3 & GJ3470
ID:
ivo://CDS.VizieR/J/AJ/157/97
Title:
Radial velocity measurements of K2-3 & GJ3470
Short Name:
J/AJ/157/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report improved masses, radii, and densities for four planets in two bright M-dwarf systems, K2-3 and GJ3470, derived from a combination of new radial velocity and transit observations. Supplementing K2 photometry with follow-up Spitzer transit observations refined the transit ephemerides of K2-3 b, c, and d by over a factor of 10. We analyze ground-based photometry from the Evryscope and Fairborn Observatory to determine the characteristic stellar activity timescales for our Gaussian Process fit, including the stellar rotation period and activity region decay timescale. The stellar rotation signals for both stars are evident in the radial velocity data and is included in our fit using a Gaussian process trained on the photometry. We find the masses of K2-3 b, K2-3 c, and GJ3470 b to be 6.48_-0.93_^+0.99^, 2.14_-1.04_^+1.08^, and 12.58_-1.28_^+1.31^ M_{Earth}_, respectively. K2-3 d was not significantly detected and has a 3{sigma} upper limit of 2.80 M_{Earth}_. These two systems are training cases for future TESS systems; due to the low planet densities ({rho}<3.7 g/cm^-3^) and bright host stars (K<9 mag), they are among the best candidates for transmission spectroscopy in order to characterize the atmospheric compositions of small planets.
333. Radial velocity measurements of 51 Peg
ID:
ivo://CDS.VizieR/J/A+A/646/A159
Title:
Radial velocity measurements of 51 Peg
Short Name:
J/A+A/646/A159
Date:
21 Oct 2021
Publisher:
CDS
Description:
The analysis of exoplanetary atmospheres by means of high-resolution spectroscopy is an expanding research field which provides information o n chemical composition, thermal structure, atmospheric dynamics and orbital velocity of exoplanets. In this work, we aim at the detection of the light reflected by the exoplanet 51 Peg b employing optical high-resolution spectroscopy. To detect the light reflected by the planetary dayside we use optical HARPS and HARPS-N spectra taken near the superior conjunction of the planet, when the flux contrast between the planet and the star is maximum. To search for the weak planetary signal, we cross-correlate the observed spectra with a high S/N stellar spectrum. We homogeneously analyze the available datasets and derive a 10^-5^ upper limit on the planet-to-star flux contrast in the optical. The upper limit on the planet-to-star flux contrast of 10^-5^ translates into a low albedo of the planetary atmosphere (A_g_~0.05-0.15 for an assumed planetary radius in the range 1.5-0.9R_Jup_, as estimated from the planet's mass).
334. Radial velocity monitoring of TOI-421
ID:
ivo://CDS.VizieR/J/AJ/160/114
Title:
Radial velocity monitoring of TOI-421
Short Name:
J/AJ/160/114
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-141137, TIC94986319), a bright (V=9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421b, has an orbital period of Pb=5.19672{+/-}0.00049days, a mass of Mb=7.17{+/-}0.66M{Earth}, and a radius of Rb=2.68_-0.18_^+0.19^R{Earth}, whereas the outer warm Neptune, TOI-421c, has a period of Pc=16.06819{+/-}0.00035days, a mass of Mc=16.42_-1.04_^+1.06^M{Earth}, a radius of Rc=5.09_-0.15_^+0.16^R{Earth}, and a density of {rho}c=0.685_-0.072_^+0.080^g/cm^3^. With its characteristics, the outer planet ({rho}c=0.685_-0.072_^+0.080^g/cm^3^) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421b and TOI-421c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Ly{alpha} transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421c if equilibrium chemistry is assumed.
335. Radial velocity observations in super-Earth systems
ID:
ivo://CDS.VizieR/J/AJ/157/52
Title:
Radial velocity observations in super-Earth systems
Short Name:
J/AJ/157/52
Date:
21 Oct 2021
Publisher:
CDS
Description:
We use radial velocity (RV) observations to search for long-period gas giant companions in systems hosting inner super-Earth (1-4 R_{Earth}_, 1-10 M_{Earth}_) planets to constrain formation and migration scenarios for this population. We consistently refit published RV data sets for 65 stars and find nine systems with statistically significant trends indicating the presence of an outer companion. We combine these RV data with AO images to constrain the masses and semi-major axes of these companions. We quantify our sensitivity to the presence of long-period companions by fitting the sample with a power-law distribution and find an occurrence rate of 39%+/-7% for companions 0.5-20 M_Jup_ and 1-20 au. Half of our systems were discovered by the transit method, and half were discovered by the RV method. While differences in the RV baselines and number of data points between the two samples lead to different sensitivities to distant companions, we find that occurrence rates of gas giant companions in each sample are consistent at the 0.5{sigma} level. We compare the frequency of Jupiter analogs in these systems to the equivalent rate from field star surveys and find that Jupiter analogs are more common around stars hosting super-Earths. We conclude that the presence of outer gas giants does not suppress the formation of inner super-Earths, and that these two populations of planets instead appear to be correlated. We also find that the stellar metallicities of systems with gas giant companions are higher than those without companions, in agreement with the well-established metallicity correlation from RV surveys of field stars.
336. Radial velocity of TOI-201
ID:
ivo://CDS.VizieR/J/AJ/161/235
Title:
Radial velocity of TOI-201
Short Name:
J/AJ/161/235
Date:
16 Mar 2022 11:46:40
Publisher:
CDS
Description:
We present the confirmation of the eccentric warm giant planet TOI-201b, first identified as a candidate in Transiting Exoplanet Survey Satellite photometry (Sectors 1-8, 10-13, and 27-28) and confirmed using ground-based photometry from Next Generation Transit Survey and radial velocities from FEROS, HARPS, CORALIE, and Minerva-Australis. TOI-201b orbits a young (0.87_-0.49_^+0.46^Gyr) and bright (V=9.07mag) F-type star with a 52.9781day period. The planet has a mass of 0.42_-0.03_^+0.05^M_J_, a radius of 1.008_-0.015_^+0.012^R_J_, and an orbital eccentricity of 0.28_-0.09_^+0.06^; it appears to still be undergoing fairly rapid cooling, as expected given the youth of the host star. The star also shows long-term variability in both the radial velocities and several activity indicators, which we attribute to stellar activity. The discovery and characterization of warm giant planets such as TOI-201b are important for constraining formation and evolution theories for giant planets.
337. R-band light curve of Qatar-1
ID:
ivo://CDS.VizieR/J/AJ/161/108
Title:
R-band light curve of Qatar-1
Short Name:
J/AJ/161/108
Date:
21 Oct 2021
Publisher:
CDS
Description:
Motivated by the unsettled conclusion on whether there are any transit timing variations (TTVs) for the exoplanet Qatar-1b, 10 new transit light curves are presented and a TTV analysis with a baseline of 1400 epochs is performed. Because the linear model provides a good fit with a reduced chi-square of {chi}_red_^2^=2.59 and the false-alarm probabilities of the possible TTV frequencies are as large as 35%, our results are consistent with a null-TTV model. Nevertheless, a new ephemeris with a reference time of T0=2455647.63360{+/-}0.00008 (BJD) and a period of P=1.4200236{+/-}0.0000001day is obtained. In addition, the updated orbital semimajor axis and planetary radius in units of stellar radius are provided, and the lower limit of the modified stellar tidal quality factor is also determined.
338. Relative radial velocities and K2 fluxes of K2-132
ID:
ivo://CDS.VizieR/J/A+A/613/A76
Title:
Relative radial velocities and K2 fluxes of K2-132
Short Name:
J/A+A/613/A76
Date:
21 Oct 2021
Publisher:
CDS
Description:
Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P<~10-days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017AJ....154..254G). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff=4878+/-70K, logg=3.289+/-0.004, and [Fe/H]=-0.11+/-0.05dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P=9.1708+/-0.0025d, e=0.290+/-0.049, Mp=0.495+/-0.007M_J_ and Rp=1.089+/-0.006R_J_. This is the fifth known planet orbiting any giant star with a<0.1, and the most eccentric one among them, making K2-132 b a very interesting object.
339. Revised radii of KIC stars & planets using Gaia DR2
ID:
ivo://CDS.VizieR/J/ApJ/866/99
Title:
Revised radii of KIC stars & planets using Gaia DR2
Short Name:
J/ApJ/866/99
Date:
21 Oct 2021
Publisher:
CDS
Description:
One bottleneck for the exploitation of data from the Kepler mission for stellar astrophysics and exoplanet research has been the lack of precise radii and evolutionary states for most of the observed stars. We report revised radii of 177911 Kepler stars derived by combining parallaxes from the Gaia Data Release 2 with the DR25 Kepler Stellar Properties Catalog. The median radius precision is ~8%, a typical improvement by a factor of 4-5 over previous estimates for typical Kepler stars. We find that ~67% (~120000) of all Kepler targets are main-sequence stars, ~21% (~37000) are subgiants, and ~12% (~21000) are red giants, demonstrating that subgiant contamination is less severe than some previous estimates and that Kepler targets are mostly main-sequence stars. Using the revised stellar radii, we recalculate the radii for 2123 confirmed and 1922 candidate exoplanets. We confirm the presence of a gap in the radius distribution of small, close-in planets, but find that the gap is mostly limited to incident fluxes >200F_{Earth}_, and its location may be at a slightly larger radius (closer to ~2R_{Earth}_) when compared to previous results. Furthermore, we find several confirmed exoplanets occupying a previously described "hot super-Earth desert" at high irradiance, show the relation between a gas-giant planet's radius and its incident flux, and establish a bona fide sample of eight confirmed planets and 30 planet candidates with Rp<2R_{Earth}_ in circumstellar "habitable zones" (incident fluxes between 0.25 and 1.50F_{Earth}_). The results presented here demonstrate the potential for transformative characterization of stellar and exoplanet populations using Gaia data.
340. RI-band LC of microlensing event OGLE-2018-BLG-1269Lb
ID:
ivo://CDS.VizieR/J/AJ/160/148
Title:
RI-band LC of microlensing event OGLE-2018-BLG-1269Lb
Short Name:
J/AJ/160/148
Date:
08 Dec 2021
Publisher:
CDS
Description:
We report the discovery of a planet in the microlensing event OGLE-2018-BLG-1269 with a planet-host mass ratio q~6x10^-4^, i.e., 0.6 times smaller than the Jupiter/Sun mass ratio. Combined with the Gaia parallax and proper motion, a strong one-dimensional constraint on the microlens parallax vector allows us to significantly reduce the uncertainties of lens physical parameters. A Bayesian analysis that ignores any information about light from the host yields that the planet is a cold giant (M_2_=0.69_-0.22_^+0.44^M_J_) orbiting a Sun-like star (M_1_=1.13_-0.35_^+0.72^M_{sun}_) at a distance of D_L_=2.56_-0.62_^+0.92^kpc. The projected planet-host separation is a_{perp}_=4.61_-1.17_^+1.70^au. Using Gaia astrometry, we show that the blended light lies <~12mas from the host and therefore must be either the host star or a stellar companion to the host. An isochrone analysis favors the former possibility at >99.6%. The host is therefore a subgiant. For host metallicities in the range of 0.0<=[Fe/H]<=+0.3, the host and planet masses are then in the range of 1.16<=M_1_/M_{sun}_<=1.38 and 0.74<=M_2_/M_J_<=0.89, respectively. Low host metallicities are excluded. The brightness and proximity of the lens make the event a strong candidate for spectroscopic follow-up both to test the microlensing solution and to further characterize the system.