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 Distinction between Extra-solar Planets and Low-mass Secondaries

1999 ◽  
Vol 170 ◽  
pp. 131-142
Author(s):  
Tsevi Mazeh
Keyword(s):  
Solar System ◽  
Mass Distribution ◽  
A Priori ◽  
Giant Planets ◽  
Spectroscopic Binaries ◽  
Brown Dwarf ◽  
Low Mass ◽  
Characteristic Features ◽  
Two Populations ◽  
Obvious Feature

AbstractThis paper discusses the distinction between extra-solar planets and low-mass secondaries, in principle as well as in practice. Adopting a distinction based on the presumed different processes of formation, the paper compares the characteristic features of the giant planets in our solar system with those of the low-mass secondaries in spectroscopic binaries. The discussion reveals that there is no a priori obvious feature that can identify planets. Instead, this work considers the extremely small emerging population of discovered extra-solar planets. Based on the nine “planet-candidates” discovered as of mid-1998, it was found that their mass distribution is remarkably different from the distribution of low-mass secondaries. The transition between the two populations probably occurs at 10−30 Jupiter masses. This transition could reflect the borderline between planet and brown dwarf secondary masses.

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 Very Low-Luminosity Objects in Star-Forming Regions

1998 ◽  
Vol 11 (1) ◽  
pp. 423-424
Author(s):  
Motohide Tamura ◽  
Yoichi Itoh ◽  
Yumiko Oasa ◽  
Alan Tokunaga ◽  
Koji Sugitani
Keyword(s):  
Brown Dwarfs ◽  
Mass Function ◽  
T Tauri Stars ◽  
Initial Mass Function ◽  
Formation Mechanisms ◽  
Star Forming ◽  
Star Forming Regions ◽  
T Tauri ◽  
Low Mass ◽  
Stellar Sources

Abstract In order to tackle the problems of low-mass end of the initial mass function (IMF) in star-forming regions and the formation mechanisms of brown dwarfs, we have conducted deep infrared surveys of nearby molecular clouds. We have found a significant population of very low-luminosity sources with IR excesses in the Taurus cloud and the Chamaeleon cloud core regions whose extinction corrected J magnitudes are 3 to 8 mag fainter than those of typical T Tauri stars in the same cloud. Some of them are associated with even fainter companions. Follow-up IR spectroscopy has confirmed for the selected sources that their photospheric temperature is around 2000 to 3000 K. Thus, these very low-luminosity young stellar sources are most likely very low-mass T Tauri stars, and some of them might even be young brown dwarfs.

scholarly journals FURTHER DEFINING SPECTRAL TYPE “Y” AND EXPLORING THE LOW-MASS END OF THE FIELD BROWN DWARF MASS FUNCTION

2012 ◽  
Vol 753 (2) ◽  
pp. 156 ◽  
Author(s):  
J. Davy Kirkpatrick ◽  
Christopher R. Gelino ◽  
Michael C. Cushing ◽  
Gregory N. Mace ◽  
Roger L. Griffith ◽  
...  
Keyword(s):  
Spectral Type ◽  
Mass Function ◽  
Brown Dwarf ◽  
Low Mass

scholarly journals The Globular Cluster Population of X-ray Binaries

1987 ◽  
Vol 125 ◽  
pp. 187-197 ◽  
Author(s):  
Frank Verbunt ◽  
Piet Hut
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Mass Function ◽  
Initial Mass Function ◽  
Encounter Rate ◽  
Formation Mechanisms ◽  
Main Sequence Stars ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

We discuss formation mechanisms for low-mass X-ray binaries in globular clusters. We apply the most efficient mechanism, tidal capture in close two-body encounters between neutron and main-sequence stars, to the clusters of our galaxy. The observed number of X-ray sources in these can be explained if the birth velocities of neutron stars are higher than estimated from velocity measurements of radiopulsars, or if the initial mass function steepens at high masses. We perform a statistical test on the distribution of X-ray sources with respect to the number of close encounters in globular clusters, and find satisfactory agreement between the tidal capture theory and observation, apart from the presence of low-mass X-ray binaries in four clusters with a very low encounter rate: Ter 1, Ter 2, Gr 1 and NGC 6712.EXOSAT observations indicate that some dim globular cluster sources may be less luminous than hitherto assumed, and support the view that the brighter dim sources may be soft X-ray transients in quiescence.

scholarly journals Brown Dwarf Binaries

2011 ◽  
Vol 7 (S282) ◽  
pp. 105-110 ◽  
Author(s):  
Katelyn N. Allers
Keyword(s):  
Brown Dwarfs ◽  
Theoretical Models ◽  
Solar Neighborhood ◽  
Test Model ◽  
Brown Dwarf ◽  
Fundamental Properties ◽  
Model Predictions ◽  
Low Mass ◽  
Formation And Evolution ◽  
Insight Into

AbstractNearly 500 brown dwarfs have been discovered in recent years. The majority of these brown dwarfs exist in the solar neighborhood, yet determining their fundamental properties (mass, age, temperature & metallicity) has proved to be quite difficult, with current estimates relying heavily on theoretical models. Binary brown dwarfs provide a unique opportunity to empirically determine fundamental properties, which can then be used to test model predictions. In addition, the observed binary fractions, separations, mass ratios, & orbital eccentricities can provide insight into the formation mechanism of these low-mass objects. I will review the results of various brown dwarf multiplicity studies, and will discuss what we have learned about the formation and evolution of brown dwarfs by examining their binary properties as a function of age and mass.

scholarly journals Discovery of a brown dwarf companion to the star HIP 64892

2018 ◽  
Vol 615 ◽  
pp. A160 ◽  
Author(s):  
A. Cheetham ◽  
M. Bonnefoy ◽  
S. Desidera ◽  
M. Langlois ◽  
A. Vigan ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
Angular Separation ◽  
Dual Band ◽  
Spectral Energy ◽  
Mass Ratio ◽  
Atmospheric Models ◽  
Brown Dwarf ◽  
Low Mass ◽  
Formation And Evolution ◽  
Projected Distance

We report the discovery of a bright, brown dwarf companion to the star HIP 64892, imaged with VLT/SPHERE during the SHINE exoplanet survey. The host is a B9.5V member of the Lower-Centaurus-Crux subgroup of the Scorpius Centaurus OB association. The measured angular separation of the companion (1.2705 ± 0.0023”) corresponds to a projected distance of 159 ± 12 AU. We observed the target with the dual-band imaging and long-slit spectroscopy modes of the IRDIS imager to obtain its spectral energy distribution (SED) and astrometry. In addition, we reprocessed archival NACO L-band data, from which we also recover the companion. Its SED is consistent with a young (<30 Myr), low surface gravity object with a spectral type of M9γ ± 1. From comparison with the BT-Settl atmospheric models we estimate an effective temperature of Teff = 2600 ± 100 K, and comparison of the companion photometry to the COND evolutionary models yields a mass of ~29−37 MJ at the estimated age of 16−7+15 Myr for the system. The star HIP 64892 is a rare example of an extreme-mass ratio system (q ~ 0.01) and will be useful for testing models relating to the formation and evolution of such low-mass objects.

scholarly journals Globular Clusters: Low Mass Stars, Still No Brown Dwarfs!

2003 ◽  
Vol 211 ◽  
pp. 215-222
Author(s):  
Guido De Marchi
Keyword(s):  
Globular Clusters ◽  
Functional Form ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Brown Dwarf ◽  
Low Mass Stars ◽  
Homogeneous Sample ◽  
Original Mass ◽  
Low Mass ◽  
The Imf

In spite of all the attempts to find them, no one has yet detected any brown dwarf in a globular cluster. Although powerful instruments such as the VLT and Advanced Camera could further push the frontiers of this search, globular clusters will probably hold tight to their secrets for a while longer. Nonetheless, the search for very low mass stars in globular clusters has taught us a lot about their original mass distribution (IMF) and its evolution in time. I shall review the results of an investigation carried out over what is presently the largest, most homogeneous sample, and discuss the reasons suggesting that: 1. dynamical evolution (internal and external) has reshaped the cluster mass function over time, but the imprint of the IMF is still visible; 2. the IMF appears to vary very little from cluster to cluster; 3. the most likely functional form of the IMF is that of a power law that rises to a peak at ˜ 0.3 M⊙ and tapers off at smaller masses.

scholarly journals VERY LOW-MASS STELLAR AND SUBSTELLAR COMPANIONS TO SOLAR-LIKE STARS FROM MARVELS. VI. A GIANT PLANET AND A BROWN DWARF CANDIDATE IN A CLOSE BINARY SYSTEM HD 87646

2016 ◽  
Vol 152 (5) ◽  
pp. 112 ◽  
Author(s):  
Bo Ma(馬波) ◽  
Jian Ge ◽  
Alex Wolszczan ◽  
Matthew W. Muterspaugh ◽  
Brian Lee ◽  
...  
Keyword(s):  
Binary System ◽  
Giant Planet ◽  
Close Binary System ◽  
Close Binary ◽  
Brown Dwarf ◽  
Low Mass ◽  
Substellar Companions

scholarly journals Comparison between Extrasolar Planets and Low-Mass Secondaries

2001 ◽  
Vol 200 ◽  
pp. 519-528 ◽  
Author(s):  
Tsevi Mazeh ◽  
Shay Zucker
Keyword(s):  
Negative Correlation ◽  
Orbital Period ◽  
Extrasolar Planets ◽  
Spectroscopic Binaries ◽  
Statistical Features ◽  
Mass Distributions ◽  
Period Distribution ◽  
Short Period ◽  
Low Mass ◽  
Two Populations

This paper compares the statistical features of the sample of discovered extrasolar planets with those of the secondaries in nearby spectroscopic binaries, in order to enable us to distinguish between the two populations. Based on 32 planet candidates discovered until March 2000, we find that their eccentricity and period distribution are surprisingly similar to those of the binary population, while their mass distribution is remarkably different. The mass distributions definitely support the idea of two distinct populations, suggesting the planet candidates are indeed extrasolar planets. The transition between the two populations probably occurs at 10–30 Jupiter masses. We point out a possible negative correlation between the orbital period of the planets and the metallicity of their parent stars, which holds only for periods less than about 100 days. These short-period systems are characterized by circular or almost circular orbits.

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