CORALIE radial-velocity search for companions around evolved stars (CASCADES). I. Sample definition and first results: Three new planets orbiting giant stars

AbstractWe present and highlight the first results of the three main exoplanet surveys we are currently conducting at Universidad de Chile: CHEPS, Red Giant Exoplanets (radial velocity), and TraMoS (transit lightcurves). We have several interesting candidates at the Calan-Hertfordshire Extrasolar Planet Search (CHEPS) project, which is aimed at searching for the currently missing southern bright transiting planets at a few m/s radial velocity precision. Using the same technique, we are also characterizing the planetary population in a constrained sample of Red Giant stars. The Transit Monitoring from the South (TraMoS) project is aimed both at improving transit parameters and at detecting any kind of lightcurve variability from several known southern exoplanet systems.

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Radial Velocity and Chemical Composition of Evolved Stars in the Open Clusters NGC 6940 and Tombaugh 5

The Astronomical Journal ◽

10.3847/1538-3881/aae57e ◽

2018 ◽

Vol 156 (5) ◽

pp. 244 ◽

Cited By ~ 1

Author(s):

Martina Baratella ◽

Giovanni Carraro ◽

Valentina D’Orazi ◽

Eugene A. Semenko

Keyword(s):

Chemical Composition ◽

Radial Velocity ◽

Open Clusters ◽

Evolved Stars

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Masses of the components of SB2 binaries observed with Gaia – V. Accurate SB2 orbits for 10 binaries and masses of the components of 5 binaries

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1571 ◽

2020 ◽

Vol 496 (2) ◽

pp. 1355-1368

Author(s):

J-L Halbwachs ◽

F Kiefer ◽

Y Lebreton ◽

H M J Boffin ◽

F Arenou ◽

...

Keyword(s):

Radial Velocity ◽

Binary Stars ◽

Main Sequence ◽

Spectroscopic Binaries ◽

Orbital Elements ◽

Evolved Stars ◽

The Individual ◽

The Masses ◽

Stellar Masses ◽

Selection Of

ABSTRACT Double-lined spectroscopic binaries (SB2s) are one of the main sources of stellar masses, as additional observations are only needed to give the inclinations of the orbital planes in order to obtain the individual masses of the components. For this reason, we are observing a selection of SB2s using the SOPHIE spectrograph at the Haute-Provence observatory in order to precisely determine their orbital elements. Our objective is to finally obtain masses with an accuracy of the order of one per cent by combining our radial velocity (RV) measurements and the astrometric measurements that will come from the Gaia satellite. We present here the RVs and the re-determined orbits of 10 SB2s. In order to verify the masses, we will derive from Gaia, we obtained interferometric measurements of the ESO VLTI for one of these SB2s. Adding the interferometric or speckle measurements already published by us or by others for four other stars, we finally obtain the masses of the components of five binary stars, with masses ranging from 0.51 to 2.2 solar masses, including main-sequence dwarfs and some more evolved stars whose location in the HR diagram has been estimated.

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The Pan-Pacific Planet Search – VIII. Complete results and the occurrence rate of planets around low-luminosity giants

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3378 ◽

2019 ◽

Vol 491 (4) ◽

pp. 5248-5257 ◽

Cited By ~ 3

Author(s):

Robert A Wittenmyer ◽

R P Butler ◽

Jonathan Horner ◽

Jake Clark ◽

C G Tinney ◽

...

Keyword(s):

Radial Velocity ◽

Main Sequence ◽

Giant Planets ◽

Occurrence Rate ◽

Velocity Measurements ◽

Intermediate Mass ◽

Giant Stars ◽

Intermediate Mass Stars ◽

Final Data ◽

Solar Type

ABSTRACT Our knowledge of the populations and occurrence rates of planets orbiting evolved intermediate-mass stars lags behind that for solar-type stars by at least a decade. Some radial velocity surveys have targeted these low-luminosity giant stars, providing some insights into the properties of their planetary systems. Here, we present the final data release of the Pan-Pacific Planet Search (PPPS), a 5 yr radial velocity survey using the 3.9 m Anglo-Australian Telescope. We present 1293 precise radial velocity measurements for 129 stars, and highlight 6 potential substellar-mass companions, which require additional observations to confirm. Correcting for the substantial incompleteness in the sample, we estimate the occurrence rate of giant planets orbiting low-luminosity giant stars to be approximately 7.8$^{+9.1}_{-3.3}$ per cent. This result is consistent with the frequency of such planets found to orbit main-sequence A-type stars, from which the PPPS stars have evolved.

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Asteroseismology of evolved stars to constrain the internal transport of angular momentum

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833447 ◽

2019 ◽

Vol 621 ◽

pp. A66 ◽

Cited By ~ 14

Author(s):

P. Eggenberger ◽

S. Deheuvels ◽

A. Miglio ◽

S. Ekström ◽

C. Georgy ◽

...

Keyword(s):

Angular Momentum ◽

Transport Process ◽

Main Sequence ◽

Red Giants ◽

Rotation Rates ◽

Giant Stars ◽

Evolved Stars ◽

Surface Rotation ◽

Red Giant ◽

Internal Transport

Context. The observations of solar-like oscillations in evolved stars have brought important constraints on their internal rotation rates. To correctly reproduce these data, an efficient transport mechanism is needed in addition to the transport of angular momentum by meridional circulation and shear instability. The efficiency of this undetermined process is found to increase both with the mass and the evolutionary stage during the red giant phase. Aims. We study the efficiency of the transport of angular momentum during the subgiant phase. Methods. The efficiency of the unknown transport mechanism is determined during the subgiant phase by comparing rotating models computed with an additional corresponding viscosity to the asteroseismic measurements of both core and surface-rotation rates for six subgiants observed by the Kepler spacecraft. We then investigate the change in the efficiency of this transport of angular momentum with stellar mass and evolution during the subgiant phase. Results. The precise asteroseismic measurements of both core and surface-rotation rates available for the six Kepler targets enable a precise determination of the efficiency of the transport of angular momentum needed for each of these subgiants. These results are found to be insensitive to all the uncertainties related to the modelling of rotational effects before the post-main sequence (poMS) phase. An interesting exception in this context is the case of young subgiants (typical values of log(g) close to 4), because their rotational properties are sensitive to the degree of radial differential rotation on the main sequence (MS). These young subgiants constitute therefore perfect targets to constrain the transport of angular momentum on the MS from asteroseismic observations of evolved stars. As for red giants, we find that the efficiency of the additional transport process increases with the mass of the star during the subgiant phase. However, the efficiency of this undetermined mechanism decreases with evolution during the subgiant phase, contrary to what is found for red giants. Consequently, a transport process with an efficiency that increases with the degree of radial differential rotation cannot account for the core-rotation rates of subgiants, while it correctly reproduces the rotation rates of red giant stars. This suggests that the physical nature of the additional mechanism needed for the internal transport of angular momentum may be different in subgiant and red giant stars.

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CARMENES – M Dwarfs and their Planets: First Results

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317004070 ◽

2016 ◽

Vol 12 (S328) ◽

pp. 46-53 ◽

Cited By ~ 1

Author(s):

A. Quirrenbach ◽

P.J. Amado ◽

I. Ribas ◽

A. Reiners ◽

J.A. Caballero ◽

...

Keyword(s):

High Resolution ◽

Radial Velocity ◽

Wavelength Range ◽

Southern Spain ◽

Science Program ◽

Velocity Measurements ◽

M Dwarfs ◽

First Results ◽

Calar Alto

AbstractCARMENES is a pair of high-resolution (R ≳ 80, 000) spectrographs covering the wavelength range from 0.52 to 1.71 μm with only small gaps. The instrument has been optimized for precise radial velocity measurements. It was installed and commissioned at the 3.5 m telescope of the Calar Alto observatory in Southern Spain in 2015. The first large science program of CARMENES is a survey of ~300 M dwarfs, which started on Jan 1, 2016. We present an overview of the instrument, and provide a few examples of early science results.

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HD 101065, the most peculiar star: First results from precise radial velocity study

Journal of Astrophysics and Astronomy ◽

10.1007/bf02702326 ◽

2005 ◽

Vol 26 (2-3) ◽

pp. 185-191 ◽

Cited By ~ 8

Author(s):

D. E. Mkrtichian ◽

A. P. Hatzes

Keyword(s):

Radial Velocity ◽

Peculiar Star ◽

First Results

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307004139 ◽

2006 ◽

Vol 2 (S240) ◽

pp. 261-263 ◽

Cited By ~ 2

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.

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