scholarly journals Derivation of orbital parameters of very low mass companions in double stars from radial velocities and observations of space astrometry missions like HIPPARCOS, DIVA and GAIA

1999 ◽  
Vol 170 ◽  
pp. 410-415
Author(s):  
H.-H. Bernstein
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Brown Dwarfs ◽  
Optimal Estimation ◽  
Velocity Measurements ◽  
Orbital Parameters ◽  
Double Stars ◽  
Observation Methods ◽  
Low Mass ◽  
Space Astrometry

AbstractRadial velocity measurements are a well known high-precision method to obtain the orbits of extrasolar planets or brown dwarfs. However, this method is not able to determine the inclination which could be derived from astrometry. The astrometric effects of those objects are very minute, wherefore the interest of astronomers in astrometric techniques was very poor. This situation changes fundamentally since space astrometry observations are available. HIPPARCOS demonstrated the power of space astrometry and the extremely high accuracy of the DIVA, and especially the GAIA observations allows one to detect Jupiter- and Earth- like objects. The optimal estimation of the parameters of the orbit of extrasolar planets or brown dwarfs is a combination of radial velocity measurements and space astrometry observations. Here it is possible to overcome problems which are inherent in both observation methods, so space astrometry complements radial velocity observations and vice versa. This paper gives a method for the parameter estimation using both types of measurements.

scholarly journals Periodic transit timing variations and refined system parameters of the exoplanet XO-6b

2019 ◽  
Author(s):  
Zoltán Garai ◽  
Theodor Pribulla ◽  
Richard Komžík ◽  
Emil Kundra ◽  
Ľubomír Hambálek ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Rotating Stars ◽  
Velocity Measurements ◽  
Orbital Parameters ◽  
Orbit Inclination ◽  
Consistent Solution ◽  
Low Mass ◽  
Academy Of Sciences ◽  
Fast Rotating

Abstract Only a few exoplanets are known to orbit around fast rotating stars. One of them is XO-6b, which orbits an F5V-type star. Shortly after the discovery, we started multicolor photometric and radial-velocity follow-up observations of XO-6b, using the telescopes of Astronomical Institute of the Slovak Academy of Sciences. Our main scientific goals were to better characterize the planetary system and to search for transit timing variations. We refined several planetary and orbital parameters. Based on our measurements, the planet XO-6b seems to be about 10% larger, which is, however, only about 2σ difference, but its orbit inclination angle, with respect to the plane of the sky, seems to be significantly smaller, than it was determined originally by the discoverers. In this case we found about 9.5σ difference. Moreover, we observed periodic transit timing variations of XO-6b with a semi-amplitude of about 14 min and with a period of about 450 days. There are two plausible explanations of such transit timing variations: (1) a third object in the system XO-6 causing light-time effect, or (2) resonant perturbations between the transiting planet XO-6b and another unknown low-mass planet in this system. From the O-C diagram we derived that the assumed third object in the system should have a stellar mass, therefore significant variations are expected in the radial-velocity measurements of XO-6. Since this is not the case, and since all attempts to fit radial velocities and O-C data simultaneously failed to provide a consistent solution, more realistic is the second explanation.

scholarly journals The CORALIE survey for southern extrasolar planets

2019 ◽  
Vol 625 ◽  
pp. A71 ◽  
Author(s):  
E. L. Rickman ◽  
D. Ségransan ◽  
M. Marmier ◽  
S. Udry ◽  
F. Bouchy ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Main Sequence ◽  
Extrasolar Planets ◽  
Brown Dwarfs ◽  
Main Sequence Stars ◽  
Period Range ◽  
Orbital Parameters ◽  
Long Period ◽  
Long Term Trends

Context. Since 1998, a planet-search around main sequence stars within 50 pc in the southern hemisphere has been underway with the CORALIE spectrograph at La Silla Observatory. Aims. With an observing time span of more than 20 yr, 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. Methods. Long-term precise Doppler measurements with the CORALIE spectrograph reveal radial-velocity signatures of massive planetary companions and brown dwarfs on long-period orbits. Results. 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 15.6–40.4 yr and a mass domain of 2.93–26.77 MJup, the latter of which straddles the nominal boundary between planets and brown dwarfs. Conclusions. 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.

Radial Velocity Detectability of Low‐Mass Extrasolar Planets in Close Orbits

2005 ◽  
Vol 620 (2) ◽  
pp. 1002-1009 ◽  
Author(s):  
Raman Narayan ◽  
Andrew Cumming ◽  
D. N. C. Lin
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Low Mass

scholarly journals Searching for Planetary Companions to Ultracool Dwarfs: Planet Hunting in the Near Infrared

2008 ◽  
Vol 4 (S253) ◽  
pp. 346-349
Author(s):  
Cullen H. Blake ◽  
David Charbonneau ◽  
David W. Latham
Keyword(s):  
Radial Velocity ◽  
Near Infrared ◽  
Extrasolar Planets ◽  
Terrestrial Planets ◽  
Habitable Zone ◽  
Velocity Measurements ◽  
Ultracool Dwarfs

AbstractOwing to their small masses and radii, Ultracool Dwarfs (UCDs; late-M, L, and T dwarfs) may be excellent targets for planet searches and may afford astronomers the opportunity to detect terrestrial planets in the habitable zone. The precise measurements necessary to detect extrasolar planets orbiting UCDs represent a major challenge. We describe two efforts to obtain precise measurements of UCDs in the Near Infrared (NIR). The first involves the robotic NIR observatory PAIRITEL and efforts to obtain photometric precision sufficient for the detection of terrestrial planets transiting UCDs. The second effort involves precise radial velocity measurements of UCDs in the NIR and a survey undertaken with the NIRSPEC spectrograph on Keck.

scholarly journals A possible dividing line between massive planets and brown-dwarf companions

2010 ◽  
Vol 6 (S276) ◽  
pp. 117-120 ◽  
Author(s):  
Johannes Sahlmann ◽  
Damien Ségransan ◽  
Didier Queloz ◽  
Stéphane Udry
Keyword(s):  
Radial Velocity ◽  
Formation Process ◽  
Brown Dwarfs ◽  
Mass Range ◽  
Velocity Measurements ◽  
Brown Dwarf ◽  
The One ◽  
The Individual ◽  
Dividing Line

AbstractBrown dwarfs are intermediate objects between planets and stars. The lower end of the brown-dwarf mass range overlaps with the one of massive planets and therefore the distinction between planets and brown-dwarf companions may require to trace the individual formation process. We present results on new potential brown-dwarf companions of Sun-like stars, which were discovered using CORALIE radial-velocity measurements. By combining the spectroscopic orbits and Hipparcos astrometric measurements, we have determined the orbit inclinations and therefore the companion masses for many of these systems. This has revealed a mass range between 25 and 45 Jupiter masses almost void of objects, suggesting a possible dividing line between massive planets and sub-stellar companions.

scholarly journals Transit & RV Observations of Exoplanets by the 1-m Telescope at Weihai

2012 ◽  
Vol 8 (S293) ◽  
pp. 33-35
Author(s):  
Chen Cao ◽  
Dayong Ren ◽  
Dongyang Gao ◽  
Jicheng Zhang ◽  
Nan Song ◽  
...  
Keyword(s):  
High Resolution ◽  
Radial Velocity ◽  
Extrasolar Planets ◽  
Physical Parameters ◽  
Velocity Measurements ◽  
Preliminary Results

AbstractBy using the 1-m reflecting telescope at Weihai Observatory of Shandong University, the transit observations of seven stars are carried out to accurately estimate the physical parameters of extrasolar planets. Besides, a new high-resolution spectrograph (WES) was installed on this telescope for radial velocity measurements on exoplanets, we will show some preliminary results.

scholarly journals The ELODIE and SOPHIE Search for Northern Extrasolar Planets: Jupiter-Analogs around Sun-Like Stars

2012 ◽  
Vol 8 (S293) ◽  
pp. 445-447
Author(s):  
I. Boisse ◽  
F. Pepe ◽  
C. Perrier ◽  
D. Queloz ◽  
F. Bouchy ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Extrasolar Planets ◽  
Velocity Measurements ◽  
Long Period

AbstractWe present radial-velocity measurements (RV) obtained in one of the numbers of programs underway to search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m telescope of the Observatoire de Haute-Provence. Targets were selected from catalogs observed with ELODIE, which had been mounted previously at the telescope, in order to detect long-period planets with an extended database close to 15 years.

scholarly journals Search for Low-Mass Planets Around Late-M Dwarfs Using IRD

2012 ◽  
Vol 8 (S293) ◽  
pp. 201-203
Author(s):  
Masashi Omiya ◽  
Bun'ei Sato ◽  
Hiroki Harakawa ◽  
Masayuki Kuzuhara ◽  
Teruyuki Hirano ◽  
...  
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Near Infrared ◽  
Frequency Comb ◽  
Habitable Zone ◽  
Velocity Measurements ◽  
M Dwarfs ◽  
Low Mass ◽  
Rocky Planets ◽  
Theoretical Simulations

AbstractWe have a plan to conduct a Doppler planet search for low-mass planets around nearby middle-to-late M dwarfs using IRD. IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. We expect to achieve the accuracy of the radial velocity measurements of 1 m/s using IRD with a frequency comb as a wavelengh calibrator. Thus, we would detect super-Earths in habitable zone and low-mass rocky planets in close-in orbits around late-M dwarfs. In this survey, we aim to understand and discuss statistical properties of low-mass planets around low-mass M dwarfs compared with those derived from theoretical simulations.

scholarly journals Formation of Planetary-Mass Brown Dwarfs in Magnetic Molecular Clouds

2003 ◽  
Vol 211 ◽  
pp. 23-26 ◽  
Author(s):  
Alan P. Boss
Keyword(s):  
Molecular Clouds ◽  
Extrasolar Planets ◽  
Three Dimensional ◽  
Brown Dwarfs ◽  
Young Star ◽  
Low Mass ◽  
Protostellar Collapse ◽  
The Masses ◽  
Floating Objects ◽  
Order Four

Searches for very low mass objects in young star clusters have uncovered evidence for free-floating objects with inferred masses possibly as low as 5 to 15 Jupiter masses (MJup), similar to the masses of several extrasolar planets. We show here that the process which forms single and multiple protostars, namely collapse and fragmentation of molecular clouds, might be able to produce self-gravitating objects with initial masses less than ˜ 1MJup. Models are calculated with a three dimensional, finite differences code which solves the equations of hydrodynamics, gravitation, and radiative transfer in the Eddington and diffusion approximations. Magnetic pressure is added to the gas pressure, magnetic tension is approximated by gravity dilution once collapse is well underway, and ambipolar diffusion is treated approximately as well. Initially oblate clouds fragment into multiple protostar systems containing a small number (of order four) of fragments. If such fragments can be ejected from an unstable quadruple protostar system, prior to gaining significantly more mass, protostellar collapse might then be able to explain the formation of free-floating objects with masses below 13MJup. These objects might then be best termed “sub-brown dwarfs”.

scholarly journals High Precision Photometry from EulerCam and TRAPPIST: The Case of WASP-42, WASP-49 and WASP-50

2012 ◽  
Vol 8 (S293) ◽  
pp. 119-121
Author(s):  
Monika Lendl ◽  
Michaël Gillon ◽  
Didier Queloz
Keyword(s):  
Radial Velocity ◽  
High Precision ◽  
Extrasolar Planets ◽  
High Accuracy ◽  
Velocity Measurements ◽  
Very High

AbstractTransiting extrasolar planets provide unmatched insights into the structure and composition of close-in planets. When a planet transits its host star, its radius is known, which together with radial velocity measurements, allows accessing the planetary density. We present results obtained using the Euler and TRAPPIST telescopes that aim at reaching very high accuracy on the parameters derived from transit lightcurves. Here, we show the case of the recently discovered WASP-42b and WASP-49b and new observations of WASP-50b.

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