Determining the mass of RV exoplanet candidates using Gaia

2020 ◽  
Author(s):  
Flavien Kiefer ◽  
Guillaume Hébrard ◽  
Alain Lecavelier ◽  
Eder Martoli ◽  
Shweta Dalal ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extreme Values ◽  
Minimum Mass ◽  
True Nature ◽  
Astronomical Object ◽  
On Line ◽  
M Dwarf ◽  
True Mass

<p>Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplanets in on-line database, such as exoplanet.eu or the NASA exoplanet archive, still lacks a measurement of their true mass, in particular those detected thanks to radial velocity (RV) variations of their host star. For those, only the minimum mass, or m sin(i), is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane-of-the-sky. The mass that is given in database is generally that of an assumed edge-on system (90 degrees), but many other inclinations are likely, even extreme values closer to 0 degree (face-on configuration). In such case, the mass of the published object could be strongly underestimated, even by 1 or 2 orders of magnitude. We used a recently developed tool, called GASTON (Kiefer et al. 2019b & 2019c), to take advantage of the voluminous Gaia astrometric database, in order to constrain the inclination and true mass of several hundreds of published exoplanet candidates (Kiefer et al. 2020, submitted). In this presentation, we will present the method and report on several exoplanet candidates reclassified in the stellar domain, among which unknown brown/M-dwarf. We also confirm the planetary nature of a few tens of candidates.</p>

scholarly journals Determining the true mass of radial-velocity exoplanets with Gaia

2020 ◽  
Vol 645 ◽  
pp. A7
Author(s):  
F. Kiefer ◽  
G. Hébrard ◽  
A. Lecavelier des Etangs ◽  
E. Martioli ◽  
S. Dalal ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extreme Values ◽  
Minimum Mass ◽  
Brown Dwarf ◽  
True Nature ◽  
Astronomical Object ◽  
Orbital Periods ◽  
True Mass

Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplanets lack a measurement of their true mass, in particular those detected as a result of radial-velocity (RV) variations of their host star. For those examples, only the minimum mass, or m sin i, is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane of the sky. The mass that is given in databases is generally that of an assumed edge-on system (~90°), but many other inclinations are possible, even extreme values closer to 0° (face-on). In such a case, the mass of the published object could be strongly underestimated by up to two orders of magnitude. In the present study, we use GASTON, a recently developed tool taking advantage of the voluminous Gaia astrometric database to constrain the inclination and true mass of several hundreds of published exoplanet candidates. We find nine exoplanet candidates in the stellar or brown dwarf (BD) domain, among which six were never characterized. We show that 30 Ari B b, HD 141937 b, HD 148427 b, HD 6718 b, HIP 65891 b, and HD 16760 b have masses larger than 13.5 MJ at 3σ. We also confirm the planetary nature of 27 exoplanets, including HD 10180 c, d and g. Studying the orbital periods, eccentricities, and host-star metallicities in the BD domain, we found distributions with respect to true masses consistent with other publications. The distribution of orbital periods shows of a void of BD detections below ~100 d, while eccentricity and metallicity distributions agree with a transition between BDs similar to planets and BDs similar to stars in the range 40–50 MJ.

scholarly journals The SOPHIE search for northern extrasolar planets

2018 ◽  
Vol 618 ◽  
pp. A103 ◽  
Author(s):  
M. J. Hobson ◽  
R. F. Díaz ◽  
X. Delfosse ◽  
N. Astudillo-Defru ◽  
I. Boisse ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Habitable Zone ◽  
Minimum Mass ◽  
Velocity Measurements ◽  
High Eccentricity ◽  
Dwarf Stars ◽  
M Stars ◽  
M Dwarf Stars ◽  
M Dwarf

We report the detection of two exoplanets and a further tentative candidate around the M-dwarf stars Gl96 and Gl617A, based on radial velocity measurements obtained with the SOPHIE spectrograph at the Observatoire de Haute-Provence. Both stars were observed in the context of the SOPHIE exoplanet consortium’s dedicated M-dwarf subprogramme, which aims to detect exoplanets around nearby M-dwarf stars through a systematic survey. For Gl96 we present the discovery of a new exoplanet at 73.9 d with a minimum mass of 19.66 earth masses. Gl96 b has an eccentricity of 0.44, placing it among the most eccentric planets orbiting M stars. For Gl617A we independently confirm a recently reported exoplanet at 86.7 d with a minimum mass of 31.29 earth masses. Both Gl96 b and Gl617A b are potentially within the habitable zone, although the high eccentricity of Gl96 b may take it too close to the star at periapsis.

scholarly journals Red Optical Planet Survey: A radial velocity search for low mass M dwarf planets

2013 ◽  
Vol 47 ◽  
pp. 05002
Author(s):  
J.R. Barnes ◽  
J.S. Jenkins ◽  
H.R.A. Jones ◽  
P. Rojo ◽  
P. Arriagada ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Dwarf Planets ◽  
Low Mass ◽  
M Dwarf

scholarly journals ON THE RADIAL VELOCITY DETECTION OF ADDITIONAL PLANETS IN TRANSITING, SLOWLY ROTATING M-DWARF SYSTEMS: THE CASE OF GJ 1132

2016 ◽  
Vol 153 (1) ◽  
pp. 9 ◽  
Author(s):  
Ryan Cloutier ◽  
René Doyon ◽  
Kristen Menou ◽  
Xavier Delfosse ◽  
Xavier Dumusque ◽  
...  
Keyword(s):  
Radial Velocity ◽  
M Dwarf

scholarly journals New Pulse Timing Measurements of the sdBV Star CS 1246

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Zackary L. Hutchens ◽  
Brad N. Barlow ◽  
Alan Vasquez Soto ◽  
Dan E. Reichart ◽  
Josh B. Haislip ◽  
...  
Keyword(s):  
Radial Pulsation ◽  
Minimum Mass ◽  
Velocity Measurements ◽  
Pulse Timing ◽  
Gravitational Influence ◽  
Low Mass ◽  
Robotic Telescope ◽  
M Dwarf ◽  
Long Term Trend

AbstractCS 1246 is a hot subdwarf B star discovered in 2009 to exhibit a single, large-amplitude radial pulsation. An O-C diagram constructed from this mode revealed reflex motion due to the presence of a low-mass M dwarf, as well as a long-term trend consistent with a decrease in the pulsational period. The orbital reflex motion was later confirmed with radial velocity measurements. Using eight years of data collected with the Skynet Robotic Telescope Network, we show that the pulsation amplitude of CS 1246 is decaying nonlinearly. We also present an updated O-C diagram, which might now indicate a positive Ṗ and a new 2.09 ± 0.05 yr oscillation consistent with orbital reflex motion of the entire inner sdB+dM binary, possibly due to the gravitational influence of a circumbinary planet with minimum mass

scholarly journals The CARMENES search for exoplanets around M dwarfs

2019 ◽  
Vol 622 ◽  
pp. A153 ◽  
Author(s):  
E. Nagel ◽  
S. Czesla ◽  
J. H. M. M. Schmitt ◽  
S. Dreizler ◽  
G. Anglada-Escudé ◽  
...  
Keyword(s):  
Time Series ◽  
Statistical Analysis ◽  
Likelihood Ratio Test ◽  
Ratio Test ◽  
Minimum Mass ◽  
Eccentric Orbit ◽  
M Dwarfs ◽  
High Confidence ◽  
Spectral Diagnostics ◽  
M Dwarf

We report the detection of a Neptune-mass exoplanet around the M4.0 dwarf GJ 4276 (G 232-070) based on radial velocity (RV) observations obtained with the CARMENES spectrograph. The RV variations of GJ 4276 are best explained by the presence of a planetary companion that has a minimum mass of mb sin i ≈ 16 M⊕ on a Pb = 13.35 day orbit. The analysis of the activity indicators and spectral diagnostics exclude stellar induced RV perturbations and prove the planetary interpretation of the RV signal. We show that a circular single-planet solution can be excluded by means of a likelihood ratio test. Instead, we find that the RV variations can be explained either by an eccentric orbit or interpreted as a pair of planets on circular orbits near a period ratio of 2:1. Although the eccentric single-planet solution is slightly preferred, our statistical analysis indicates that none of these two scenarios can be rejected with high confidence using the RV time series obtained so far. Based on the eccentric interpretation, we find that GJ 4276 b is the most eccentric (eb = 0.37) exoplanet around an M dwarf with such a short orbital period known today.

scholarly journals Detectability of Planets in Wide Binaries by Ground-Based Relative Astrometry with AO

2006 ◽  
Vol 2 (S240) ◽  
pp. 261-263 ◽  
Author(s):  
R. Neuhäuser ◽  
A. Seifahrt ◽  
T. Röll ◽  
A. Bedalov ◽  
M. Mugrauer
Keyword(s):  
Standard Deviation ◽  
Radial Velocity ◽  
Adaptive Optics ◽  
Periodic Variation ◽  
Square Root ◽  
Primary Star ◽  
First Results ◽  
Orbit Inclination ◽  
Pixel Scale ◽  
True Mass

AbstractMany planet candidates have been detected by radial-velocity variations of the primary star; they are planet candidates, because of the unknown orbit inclination. Detection of the wobble in the two other dimensions, to be measured by astrometry, would yield the inclination and, hence, true mass of the companions. We aim to show that planets can be confirmed or discovered in a close visual stellar binary system by measuring the astrometric wobble of the exoplanet host star as a periodic variation of the separation, even from the ground. We test the feasibility with HD 19994, a visual binary with one radial velocity planet candidate. We use the adaptive optics camera NACO at the VLT with its smallest pixel scale (∼ 13 mas) for high-precision astrometric measurements. The separations measured in 120 single images taken within one night are shown to follow white noise, so that the standard deviation can be divided by the square root of the number of images to obtain the precision. In this paper we present the first results and investigate the achievable precision in relative astrometry with adaptive optics. With careful data reduction it is possible to achieve a relative astrometric precision as low as 50 μ as for a 0″.6 binary with VLT/NACO observations in one hour, the best relative astrometric precision ever achieved with a single telescope from the ground. The relative astrometric precision demonstrated here with AO at an 8-m mirror is sufficient to detect the astrometric signal of the planet HD 19994 Ab as periodic variation of the separation between HD 19994 A and B.

scholarly journals Revisiting Proxima with ESPRESSO

2020 ◽  
Vol 639 ◽  
pp. A77 ◽  
Author(s):  
A. Suárez Mascareño ◽  
J. P. Faria ◽  
P. Figueira ◽  
C. Lovis ◽  
M. Damasso ◽  
...  
Keyword(s):  
Correlation Function ◽  
Radial Velocity ◽  
Cross Correlation ◽  
Full Width Half Maximum ◽  
Cross Correlation Function ◽  
Minimum Mass ◽  
Full Width ◽  
Half Maximum ◽  
Stellar Activity ◽  
The Cross

Context. The discovery of Proxima b marked one of the most important milestones in exoplanetary science in recent years. Yet the limited precision of the available radial velocity data and the difficulty in modelling the stellar activity calls for a confirmation of the Earth-mass planet. Aims. We aim to confirm the presence of Proxima b using independent measurements obtained with the new ESPRESSO spectrograph, and refine the planetary parameters taking advantage of its improved precision. Methods. We analysed 63 spectroscopic ESPRESSO observations of Proxima (Gl 551) taken during 2019. We obtained radial velocity measurements with a typical radial velocity photon noise of 26 cm s−1. We combined these data with archival spectroscopic observations and newly obtained photometric measurements to model the stellar activity signals and disentangle them from planetary signals in the radial velocity (RV) data. We ran a joint Markov chain Monte Carlo analysis on the time series of the RV and full width half maximum of the cross-correlation function to model the planetary and stellar signals present in the data, applying Gaussian process regression to deal with the stellar activity signals. Results. We confirm the presence of Proxima b independently in the ESPRESSO data and in the combined ESPRESSO+ HARPS+UVES dataset. The ESPRESSO data on its own shows Proxima b at a period of 11.218 ± 0.029 days, with a minimum mass of 1.29 ± 0.13 M⊕. In the combined dataset we measure a period of 11.18427 ± 0.00070 days with a minimum mass of 1.173 ± 0.086 M⊕. We get a clear measurement of the stellar rotation period (87 ± 12 d) and its induced RV signal, but no evidence of stellar activity as a potential cause for the 11.2 days signal. We find some evidence for the presence of a second short-period signal, at 5.15 days with a semi-amplitude of only 40 cm s−1. If caused by a planetary companion, it would correspond to a minimum mass of 0.29 ± 0.08 M⊕. We find that forthe case of Proxima, the full width half maximum of the cross-correlation function can be used as a proxy for the brightness changes and that its gradient with time can be used to successfully detrend the RV data from part of the influence of stellar activity. The activity-induced RV signal in the ESPRESSO data shows a trend in amplitude towards redder wavelengths. Velocities measured using the red end of the spectrograph are less affected by activity, suggesting that the stellar activity is spot dominated. This could be used to create differential RVs that are activity dominated and can be used to disentangle activity-induced and planetary-induced signals. The data collected excludes the presence of extra companions with masses above 0.6 M⊕ at periods shorter than 50 days.

scholarly journals Determining the mass of the planetary candidate HD 114762 b using Gaia

2019 ◽  
Vol 632 ◽  
pp. L9 ◽  
Author(s):  
Flavien Kiefer
Keyword(s):  
Spectral Analysis ◽  
Preceding Paper ◽  
Brown Dwarfs ◽  
Excess Noise ◽  
The Sun ◽  
Minimum Mass ◽  
Brown Dwarf ◽  
Data Release ◽  
Low Mass ◽  
M Dwarf

The first planetary candidate discovered by Latham et al. (1989, Nature, 339, 38) with radial velocities around a solar-like star other than the Sun, HD 114762 b, was detected with a minimum mass of 11 MJ. The small v sin i ∼ 0 km s−1 that is otherwise measured by spectral analysis indicated that this companion of a late-F subgiant star better corresponds to a massive brown dwarf (BD) or even a low-mass M-dwarf seen nearly face-on. To our knowledge, the nature of HD 114762 b is still undetermined. The astrometric noise measured for this system in the first data release, DR1, of the Gaia mission allows us to derive new constraints on the astrometric motion of HD 114762 and on the mass of its companion. We use the method GASTON, introduced in a preceding paper, which can simulate Gaia data and determine the distribution of inclinations that are compatible with the astrometric excess noise. With an inclination of 6.26.2+1.9−1.3 degree, the mass of the companion is constrained to Mb = 108+31−26 MJ. HD 114762 b thus indeed belongs to the M-dwarf domain, down to brown dwarfs, with Mb >  13.5 MJ at the 3σ level, and is not a planet.

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