scholarly journals Discovery of Three Very Low Mass Binary Systems: An Adaptive Optics Survey of M6.0–M7.5 Stars

2003 ◽  
Vol 211 ◽  
pp. 257-260
Author(s):  
Nick Siegler ◽  
Laird M. Close ◽  
Eric E. Mamajek ◽  
Melanie Freed
Keyword(s):  
Adaptive Optics ◽  
Binary Systems ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Low Mass ◽  
M Stars ◽  
Adaptive Optics System

We have used the adaptive optics system Hōkūpa'a at Gemini North to search for companions from a flux-limited (Ks > 12) survey of 30 nearby M6.0–M7.5 dwarfs. Our observations, which are sensitive to companions with separations > 0.1″ (~ 2.8 AU), detect 3 new binary systems. This implies an overall binary fraction of 9±4% for M6.0–M7.5 binaries. This binary frequency is somewhat less than the 19±7% measured for late M stars and ~ 20% for L stars, but is still statistically consistent. However, the result is significantly lower than the binary fractions observed amongst solar mass main sequence stars (~60%) and early M stars (~35%).

scholarly journals Age-related observations of low mass pre-main and young main sequence stars

2008 ◽  
Vol 4 (S258) ◽  
pp. 81-94 ◽  
Author(s):  
Lynne A. Hillenbrand
Keyword(s):  
Main Sequence ◽  
Rotation Period ◽  
Age Dating ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Age Related ◽  
Stellar Ages ◽  
Dating Methods ◽  
Low Mass ◽  
Lithium Depletion

AbstractThis overview summarizes the age dating methods available for young sub-solar mass stars. Pre-main sequence age diagnostics include the Hertzsprung-Russell (HR) diagram, spectroscopic surface gravity indicators, and lithium depletion; asteroseismology is also showing recent promise. Near and beyond the zero-age main sequence, rotation period or vsiniand activity (coronal and chromospheric) diagnostics along with lithium depletion serve as age proxies. Other authors in this volume present more detail in each of the aforementioned areas. Herein, I focus on pre-main sequence HR diagrams and address the questions: Do empirical young cluster isochrones match theoretical isochrones? Do isochrones predict stellar ages consistent with those derived via other independent techniques? Do the observed apparent luminosity spreads at constant effective temperature correspond to true age spreads? While definitive answers to these questions are not provided, some methods of progression are outlined.

scholarly journals Comment on “A noninteracting low-mass black hole–giant star binary system”

Science ◽  
2020 ◽  
Vol 368 (6491) ◽  
pp. eaba3282 ◽  
Author(s):  
Ed P. J. van den Heuvel ◽  
Thomas M. Tauris
Keyword(s):  
Black Hole ◽  
Main Sequence ◽  
Close Binary ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Giant Star ◽  
X Ray ◽  
Low Mass ◽  
Red Giant ◽  
Star Binary

Thompson et al. (Reports, 1 November 2019, p. 637) interpreted the unseen companion of the red giant star 2MASS J05215658+4359220 as most likely a black hole. We argue that if the red giant’s mass is ~1 solar mass, its companion can be a close binary consisting of two main-sequence stars. This would explain why no x-ray emission is detected from the system.

scholarly journals A Note about Multiple Systems of Dense Molecular Clouds

1982 ◽  
Vol 69 ◽  
pp. 105-108
Author(s):  
Peter Vanýsek
Keyword(s):  
Main Sequence ◽  
Space Distribution ◽  
Main Sequence Stars ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Multiple Systems ◽  
Ob Stars ◽  
Ir Sources ◽  
Low Mass ◽  
The Individual

AbstractThe space distribution of some small dense clouds with point-like IR sources, resembles the clustering of young OB stars. It can be assumed that such objects contain heavy obscured high-luminosity stars on the ZAMS. From the comparison of infrared and radio data it follows that in typical cases, only one B star is the source of the radiation of the cloud. The total mass of the cloud is of the order of one solar mass. If the individual fragments of the cloud are gravitationally unstable, then in the later stage of the evolution only low-mass stars are formed. One can therefore expect that young OB stars are most frequently accompanied by low-mass pre-Main Sequence stars.

scholarly journals On the mass distribution of stars in the solar neighborhood

2006 ◽  
pp. 17-20 ◽  
Author(s):  
S. Ninkovic ◽  
V. Trajkovska
Keyword(s):  
Mass Distribution ◽  
Main Sequence ◽  
Solar Neighborhood ◽  
The Sun ◽  
Main Sequence Stars ◽  
M Dwarfs ◽  
Solar Mass ◽  
Low Mass Stars ◽  
Low Mass ◽  
The Mean

The present authors analyze samples consisting of Hipparcos stars. Based on the corresponding HR diagrams they estimate masses of Main-Sequence stars from their visual magnitudes. They find that already beyond the heliocentric radius of 10 pc the effects of observational selection against K and M dwarfs become rather strong. For this reason the authors are inclined to think that the results concerning this heliocentric sphere appear as realistic, i. e. the fraction of low-mass stars (under half solar mass) is about 50% and, as a consequence, the mean star mass should be about 0.6 solar masses and Agekyan's factor about 1.2. That stars with masses higher than 5 M? are very rare is confirmed also from the data concerning more remote stars. It seems that white dwarfs near the Sun are not too frequent so that their presence cannot affect the main results of the present work significantly.

scholarly journals An Unsuccessful Search for White Dwarf Companions to Nearby Main Sequence Stars

1989 ◽  
Vol 114 ◽  
pp. 134-137
Author(s):  
Harry L. Shipman ◽  
Jeanne Geczi
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Binary Systems ◽  
Main Sequence ◽  
Main Sequence Star ◽  
Main Sequence Stars ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
M Stars

AbstractMany of the nearest white dwarf stars (e.g., Sirius B and Procyon B) are in such binaries and would have remained undiscovered if they were even a little bit further away. White dwarfs which are sufficiently hot (T(eff) > 10,000 K) would, if present in binary systems with a relatively cool (F, G, K, or M) main–sequence secondary, be visible in IUE images as a hot companion to the main sequence star. We systematically examined 318 IUE images of 280 different G, K, and M stars which had been observed for other purposes. No previously undiscovered white dwarf stars were found.

scholarly journals Are sdAs helium core stars?

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Ingrid Pelisoli ◽  
S. O. Kepler ◽  
Detlev Koester
Keyword(s):  
Main Sequence ◽  
Galactic Disk ◽  
Physical Nature ◽  
Sloan Digital Sky Survey ◽  
Distance Modulus ◽  
Main Sequence Stars ◽  
Sky Survey ◽  
Balmer Lines ◽  
Low Mass ◽  
Binary Evolution

AbstractEvolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

scholarly journals The discovery of low-mass pre-main-sequence stars in Cepheus OB3b

2003 ◽  
Vol 341 (3) ◽  
pp. 805-822 ◽  
Author(s):  
M. Pozzo ◽  
T. Naylor ◽  
R. D. Jeffries ◽  
J. E. Drew
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Low Mass

scholarly journals V392 Orionis: Observations and Evolutionary State of a Low-Mass System

1998 ◽  
Vol 11 (1) ◽  
pp. 371-371
Author(s):  
S. Narusawa ◽  
A. Yamasaki ◽  
Y. Nakamura
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Circumstellar Matter ◽  
Small Mass ◽  
Primary Component ◽  
Close Binary ◽  
Mass System ◽  
Future Evolution ◽  
Short Period ◽  
Low Mass

Although the evolution of binary systems has been qualitatively interpreted with the evolutionary scenario, the quantitative interpretation of any observed system is still unsatisfactory due to the difficulty of the quantitative treatment of mass and angular momentum transfer/loss. To reach a true understanding of the evolution of binary systems, we have to accumulate more observational evidence. So far, we have observed several binaries that are short-period and noncontact, and found the existence of extremely small-mass systems. In the present paper, we study another short-period (P=0.659d), noncontact, eclipsing binary system, V392 Ori. We have made photometric and spectroscopic observations of V392 Ori. The light curves are found to vary, suggesting the existence of circumstellar matter around the system. Combining the photometric and spectroscopic results, we obtain parameters describing the system; we find the mass of the primary component is only 0.6Mʘ- undermassive for its spectral and luminosity class A5V, suggesting that a considerable amount of its original mass has been lost from the system during the course of evolution. The low-mass problem is very important for investigation of the evolution of close binary systems: largemass loss within and/or after the main-sequence will have a significant influence on the future evolution of binary systems.

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