scholarly journals Binaries at the Bottom of the Main Sequence and below

2001 ◽  
Vol 200 ◽  
pp. 45-54 ◽  
Author(s):  
M. Mayor ◽  
S. Udry ◽  
J.-L. Halbwachs ◽  
F. Arenou
Keyword(s):  
Radial Velocity ◽  
Adaptive Optics ◽  
Mass Function ◽  
M Dwarfs ◽  
Mass Distributions ◽  
Solar Type ◽  
Low Mass ◽  
Formation And Evolution ◽  
Two Populations

Long-term radial-velocity surveys of G, K and M dwarfs of the solar neighbourhood are presented. The inferred orbital elements are discussed, focusing on the (e, log P) diagram, the mass-ratio and secondary mass distributions, and on the binary frequency of the studied samples. The proportion of companions to M dwarfs is found to be not significantly different from the binary frequency among G- and K-dwarf primaries. The mass function of stellar and planetary companions to solar-type stars strongly suggests different formation and evolution mechanisms for the two populations. Finally, beautiful mass-luminosity relations are obtained from low-mass binaries with high-precision radial-velocity measurements and adaptive optics visual data.

scholarly journals ELODIE low-mass companions to solar-type stars

2004 ◽  
Vol 202 ◽  
pp. 96-98 ◽  
Author(s):  
D. Naef ◽  
M. Mayor ◽  
D. Queloz ◽  
S. Udry ◽  
F. Arenou ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Adaptive Optics ◽  
Mass Range ◽  
Echelle Spectrograph ◽  
Inclination Angles ◽  
Solar Type ◽  
Low Mass ◽  
Astrometric Data ◽  
Radial Velocity Data ◽  
Orbital Solution

We present radial-velocity measurements for three solar-type stars (HD 127506, HD 174457 and HD 185414) hosting low-mass companions. The measurements were obtained with the ELODIE echelle spectrograph mounted on the 1.93–m telescope at Observatoire de Haute–Provence (CNRS, France) within the frame of the OHP-ELODIE Planet Search Programme. The inferred minimum masses of the detected companions are in the substellar mass range. Combining ELODIE radial-velocity data and HIPPARCOS astrometric data, the inclination angles of the orbital planes of HD 127506 and HD 174457 have been derived providing us with the de-projected masses of the companions: m2 = 44MJup for the companion of HD 127506 and m2= 0.13M⊙ for the companion of HD 174457. Moreover, using adaptive optics measurements, we show that HD 174457 is probably a (F8V + M7V + M3-4V) triple system. To date, only a minimal orbital solution is available for HD 185414.

scholarly journals CORALIE–ELODIE new planets and planetary systems. Looking for fossil traces of formation and evolution

2004 ◽  
Vol 202 ◽  
pp. 12-19 ◽  
Author(s):  
S. Udry ◽  
M. Mayor ◽  
D. Queloz
Keyword(s):  
Orbital Element ◽  
Giant Planet ◽  
Mass Function ◽  
Spectroscopic Binaries ◽  
Formation Mechanisms ◽  
Brown Dwarf ◽  
Low Mass ◽  
Formation And Evolution ◽  
Two Populations ◽  
Northern And Southern Hemispheres

6 new extra-solar planet candidates (HD 6434 b, HD 19994 b, HD 83443c, HD 92788b, HD 121504b, HD 190228b) are announced as part of our planet-search programmes in the northern and southern hemispheres. HD 83443 c is member of a 2-planet system with Saturnian and sub-Saturnian masses. Another system including a planet + a very low-mass brown dwarf orbiting HD 168443 is also presented. These 2 new systems and the new planetary detections rise to 25 the number of ELODIE and CORALIE candidates with minimum masses ≤20MJup. The orbital element distributions of giant-planet candidates, like the secondary mass function, the eccentricity and period distributions, compared to the equivalent distributions for spectroscopic binaries, strongly suggest different formation mechanisms for the two populations.

scholarly journals The Mass Distribution of Secondaries to Solar-Type Stars

2004 ◽  
Vol 191 ◽  
pp. 37-40 ◽  
Author(s):  
Helmut A. Abt ◽  
Daryl W. Willmarth
Keyword(s):  
Radial Velocity ◽  
Mass Distribution ◽  
Main Sequence ◽  
Mass Function ◽  
Spectroscopic Binaries ◽  
Orbital Elements ◽  
Main Sequence Stars ◽  
Solar Type ◽  
Low Mass ◽  
Good Agreement

AbstractTwo previous studies of the secondary mass function in spectroscopic binaries by Abt & Levy (1976) and by Duquennoy & Mayor (1991) are shown to be in good agreement if they are both plotted with the same abscissa scale. A new study of 271 main-sequence stars later than F6 V made with a radial-velocity accuracy of ±0.10 km s-1 yielded 10 new sets of orbital elements in addition to the 59 published ones. The resulting secondary mass function is nearly flat and shows that 2.2±1.5% of the primaries have low-mass (0.01–0.10 M⊙) companions. In contrast, the secondary mass function for visual binaries with separations >500 AU fits a van Rhijn function, as was shown previously by Abt and Levy.

scholarly journals R Coronae Borealis Stars: Long-Term Photometric & Spectroscopic Studies

1998 ◽  
Vol 11 (1) ◽  
pp. 379-379
Author(s):  
P.L. Cottrell ◽  
L. Skuljan ◽  
P.M. Kilmartin ◽  
C. Gilmore ◽  
W.A. Lawson
Keyword(s):  
Radial Velocity ◽  
Spectroscopic Studies ◽  
Photometric Data ◽  
Decline Phase ◽  
Dust Clouds ◽  
Medium Resolution ◽  
Formation And Evolution ◽  
R Coronae Borealis Stars ◽  
Insight Into

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory. In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

scholarly journals A microvariability study of nearby M dwarfs from the Western Italian Alps: Status update

2010 ◽  
Vol 6 (S276) ◽  
pp. 525-526
Author(s):  
Mario Damasso ◽  
Andrea Bernagozzi ◽  
Enzo Bertolini ◽  
Paolo Calcidese ◽  
Paolo Giacobbe ◽  
...  
Keyword(s):  
Italian Alps ◽  
M Dwarfs ◽  
Red Dwarfs ◽  
Typical Period ◽  
Low Mass ◽  
M Stars ◽  
Rocky Planets ◽  
Long Term Survey

AbstractSmall ground-based telescopes can effectively be used to look for transiting rocky planets around nearby low-mass M stars, as recently demonstrated for example by the MEarth project. Since December 2009 at the Astronomical Observatory of the Autonomous Region of Aosta Valley (OAVdA) we are monitoring photometrically a sample of red dwarfs with accurate parallax measurements. The primary goal of this ‘pilot study’ is the characterization of the photometric microvariability of each target over a typical period of approximately 2 months. This is the preparatory step to long-term survey with an array of identical small telescopes, with kick-off in early 2011. Here we discuss the present status of the study, describing the stellar sample, and presenting the most interesting results obtained so far, including the aggressive data analysis devoted to the characterization of the variability properties of the sample and the search for transit-like signals.

scholarly journals An ultra-short period rocky super-Earth orbiting the G2-star HD 80653

2020 ◽  
Vol 633 ◽  
pp. A133 ◽  
Author(s):  
G. Frustagli ◽  
E. Poretti ◽  
T. Milbourne ◽  
L. Malavolta ◽  
A. Mortier ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Thermal Emission ◽  
Earth Planet ◽  
Period Orbit ◽  
Short Period ◽  
Orbital Phase ◽  
Solar Type ◽  
Radial Velocity Data

Ultra-short period (USP) planets are a class of exoplanets with periods shorter than one day. The origin of this sub-population of planets is still unclear, with different formation scenarios highly dependent on the composition of the USP planets. A better understanding of this class of exoplanets will, therefore, require an increase in the sample of such planets that have accurate and precise masses and radii, which also includes estimates of the level of irradiation and information about possible companions. Here we report a detailed characterization of a USP planet around the solar-type star HD 80653 ≡EP 251279430 using the K2 light curve and 108 precise radial velocities obtained with the HARPS-N spectrograph, installed on the Telescopio Nazionale Galileo. From the K2 C16 data, we found one super-Earth planet (Rb = 1.613 ± 0.071 R⊕) transiting the star on a short-period orbit (Pb = 0.719573 ± 0.000021 d). From our radial velocity measurements, we constrained the mass of HD 80653 b to Mb = 5.60 ± 0.43 M⊕. We also detected a clear long-term trend in the radial velocity data. We derived the fundamental stellar parameters and determined a radius of R⋆ = 1.22 ± 0.01 R⊙ and mass of M⋆ = 1.18 ± 0.04 M⊙, suggesting that HD 80653 has an age of 2.7 ± 1.2 Gyr. The bulk density (ρb = 7.4 ± 1.1 g cm−3) of the planet is consistent with an Earth-like composition of rock and iron with no thick atmosphere. Our analysis of the K2 photometry also suggests hints of a shallow secondary eclipse with a depth of 8.1 ± 3.7 ppm. Flux variations along the orbital phase are consistent with zero. The most important contribution might come from the day-side thermal emission from the surface of the planet at T ~ 3480 K.

scholarly journals CARMENES: M dwarfs and their planets

2015 ◽  
Vol 11 (S320) ◽  
pp. 388-390
Author(s):  
A. Quirrenbach ◽  
P.J. Amado ◽  
J.A. Caballero ◽  
H. Mandel ◽  
R. Mundt ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Spectral Resolution ◽  
M Dwarfs ◽  
Habitable Zones ◽  
Scientific Goal ◽  
New Instrument ◽  
Fabry Perot ◽  
Calar Alto ◽  
Sufficient Precision

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a new instrument currently undergoing commissioning at the 3.5 m telescope of the Calar Alto Observatory. It has been constructed by a consortium of eleven Spanish and German institutions. The scientific goal of the project is a 600-night radial-velocity survey targeting 300 M dwarfs with sufficient precision to detect terrestrial planets in their habitable zones. The CARMENES instrument consists of two separate échelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. Both spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a long-term radial velocity precision of 1 m s−1. The wavelength calibration will be done with Th-Ne and U-Ne emission line lamps, and with Fabry-Pérot etalons.

scholarly journals How the planetary research helps to the stellar dynamo understanding

2012 ◽  
Vol 8 (S294) ◽  
pp. 471-475
Author(s):  
I. Boisse ◽  
M. Oshagh ◽  
C. Lovis ◽  
N. C. Santos ◽  
X. Dumusque ◽  
...  
Keyword(s):  
Planetary System ◽  
Magnetic Activity ◽  
Doppler Imaging ◽  
Habitable Zone ◽  
Stellar Activity ◽  
Term Variation ◽  
Solar Type ◽  
Low Mass ◽  
Stellar Dynamo

AbstractMost of the exoplanet science is dependent on the stellar knowledge. One of them that has to be understood is the magnetic activity when we search for planets with radial velocity or photometry measurements. The main shape of stellar activity and spots properties have to be understood, for example, to choose the best targets to search for low-mass planets in the habitable zone or to derive the accurate parameters of a planetary system. With that aim, we show in this presentation how these studies lead to give clues on spots latitudes and on the long term variation of stellar activity. The properties of magnetic activity on the low rotators solar-type stars are not easily reachable by other techniques (spectropolarimetry or Doppler imaging) and these studies should be used to constrain theories of stellar dynamo.

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 Bivariate luminosity-HI mass distribution function of galaxies based on the NIBLES survey

2018 ◽  
Vol 619 ◽  
pp. A89 ◽  
Author(s):  
Z. Butcher ◽  
S. Schneider ◽  
W. van Driel ◽  
M. D. Lehnert
Keyword(s):  
Mass Distribution ◽  
Luminosity Function ◽  
Hubble Constant ◽  
Mass Function ◽  
Volume Density ◽  
Local Universe ◽  
Mass Distributions ◽  
Low Mass ◽  
The Mean ◽  
Mass Distribution Function

We present a new optical luminosity-HI mass bivariate luminosity function (BLF) based on HI line observations from the Nançay Interstellar Baryons Legacy Extragalactic Survey (NIBLES). NIBLES sources lie within the local universe (900 ≤ c z ≤ 12 000 km s−1) and were chosen from SDSS DR5 such that the optical luminosity function was sampled as uniformly as possible. The HI mass function (HIMF) derived from our raw-data BLF, which is based on HI detections only, is consistent with the HIMFs derived from other optically selected surveys in that the low-mass slope is flatter than those derived from blind HI surveys. However, spanning the entire luminosity range of NIBLES, we identify a highly consistent distribution of the HI gas mass to luminosity ratio (gas-to-light ratio) with a predictable progression in the mean MHI/L r ratio as a function of L r. This consistency allows us to construct plausible gas-to-light ratio distributions for very low-luminosity bins which lie outside the NIBLES sample. We also identify a ∼10% decrease in detection fraction for galaxies fainter than log(L r) = 9.25, consistent with the expected decrease due to distance and sensitivity effects. Accounting for these trends, we reconstruct plausible gas-to-light distributions spanning luminosity bins down to log(L r) = 5.25, thus producing a corrected BLF. This corrected BLF is in good qualitative agreement with optical luminosity-HI mass distributions from the ALFALFA survey and is able to accurately reproduce blind survey HIMFs, lending credibility that this two dimensional optical luminosity-HI mass distribution is an accurate representation of the volume density distribution of galaxies in the local universe. We also note that our agreement with HIMFs from other surveys is dependent on accounting for all systematic differences such as selection method, Hubble constant and HI flux scale.

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