scholarly journals Gaia’s detectability of black hole–main sequence star binaries formed in open clusters

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Minori Shikauchi ◽  
Jun Kumamoto ◽  
Ataru Tanikawa ◽  
Michiko S Fujii
Keyword(s):  
Black Hole ◽  
Main Sequence ◽  
Star Clusters ◽  
Interstellar Extinction ◽  
Open Clusters ◽  
Main Sequence Star ◽  
Chemical Abundance ◽  
Good Test ◽  
Orbital Periods ◽  
Chemical Anomalies

Abstract Black hole–main sequence star (BH–MS) binaries are one of the targets of future data releases of the astrometric satellite Gaia. They are supposed to be formed in two main sites: a galactic field and star clusters. However, previous work has never predicted the number of BH–MS binaries originating in the latter sites. In this paper we estimate the number of BH–MS binaries formed in open clusters and detectable with Gaia based on the results of N-body simulations. By considering interstellar extinction in the Milky Way and observational constraints, we predict that ∼10 BH–MS binaries are observable. We also find that chemical abundance patterns of companion MSs will help us to identify the origin of the binaries as star clusters. Such MSs are not polluted by outflows of the BH progenitors, such as stellar winds and supernova ejecta. Chemical anomalies might be a good test to confirm the origin of binaries with relatively less massive MSs (≲5 M⊙), short orbital periods (∼1.5 yr), and higher eccentricities (e ≳0.1).

scholarly journals Observations of low mass stars in clusters: Some constraints and puzzles for stellar evolution theory

1984 ◽  
Vol 105 ◽  
pp. 123-138
Author(s):  
R.D. Cannon
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Star Clusters ◽  
Variable Stars ◽  
Open Clusters ◽  
Low Mass Stars ◽  
Theory Of Evolution ◽  
Theoretical Predictions ◽  
Low Mass ◽  
Red Giant

This review will attempt to do two things: (i) discuss some of the data which are available for testing the theory of evolution of low mass stars, and (ii) point out some problem areas where observations and theory do not seem to agree very well. This is of course too vast a field of research to be covered in one brief review, so I shall concentrate on one particular aspect, namely the study of star clusters and especially their colour-magnitude (CM) diagrams. Star clusters provide large samples of stars at the same distance and with the same age, and the CM diagram gives the easiest way of comparing theoretical predictions with observations, although crucial evidence is also provided by spectroscopic abundance analyses and studies of variable stars. Since this is primarily a review of observational data it is natural to divide it into two parts: (i) galactic globular clusters, and (ii) old and intermediate-age open clusters. Some additional evidence comes from Local Group galaxies, especially now that CM diagrams which reach the old main sequence are becoming available. For each class of cluster I shall consider successive stages of evolution from the main sequence, up the hydrogen-burning red giant branch, and through the helium-burning giant phase.

scholarly journals The Unusual Evolutionary State of Nova Scorpii 1994

2002 ◽  
Vol 187 ◽  
pp. 373-378
Author(s):  
Christopher A. Tout ◽  
Enikő Regős ◽  
Dayal Wickramasinghe
Keyword(s):  
Black Hole ◽  
Main Sequence ◽  
Main Sequence Star ◽  
Chemical Pollution ◽  
Evolutionary Status ◽  
Low Velocity ◽  
Alternative Scenario ◽  
X Ray ◽  
The Core ◽  
Evolutionary State

AbstractWe have investigated possible models for the evolutionary status of the black-hole soft X-ray transient Nova Scorpii. We propose that it is a main-sequence star in which convective overshooting, or some equivalent mixing, occurs at the core-envelope boundary. Recent detections of chemical pollution on the surface of the secondary suggest that the black hole formed in a supernova whose ejecta left and fell back at a sufficiently low velocity to accrete on to the secondary. We examine the effects of increased opacity, increased metallicity and reduced hydrogen abundance on the evolution of the secondary in the hope that these might lead to an alternative scenario. All these only exacerbate the problem.

scholarly journals Photometry of the Lower Main Sequences of Nearby Clusters

1980 ◽  
Vol 85 ◽  
pp. 255-257
Author(s):  
A. R. Upgren ◽  
E. W. Weis
Keyword(s):  
Gallium Arsenide ◽  
Main Sequence ◽  
Star Clusters ◽  
Open Clusters ◽  
National Observatory ◽  
Photoelectric Photometry ◽  
Spectral Class ◽  
Hyades Cluster

Photoelectric photometry in BVRI colors has been obtained at the Kitt Peak National Observatory of many stars in the regions of the Hyades, Praesepe and Coma star clusters which had no previous photometry. The stars were limited mostly to the lower main sequence. Their range is approximately 0.6 to 1.5 (and to 1.7 in the Hyades) in B-V and 0.25 to 0.85 (and to 1.3 in the Hyades) in R-I. Their ranges correspond from mid G through early M in spectral class. The purpose of this project is to detect and examine the main sequences of the nearest open clusters. It continues the results reported earlier in this program for the Hyades cluster [Upgren (1974), Upgren and Weis (1977)] and extends them to include Praesepe and Coma as well, by means of the new sensitive gallium-arsenide photocells which permit fainter stars to be observed with moderate sized telescopes, especially in the R and I bands.

scholarly journals The Present Data Situation for Stars in Open Clusters. II

1980 ◽  
Vol 85 ◽  
pp. 129-133
Author(s):  
J.-C. Mermilliod
Keyword(s):  
Present State ◽  
Spectral Type ◽  
Main Sequence ◽  
Open Clusters ◽  
Photometric Data ◽  
Main Sequence Star ◽  
The Sun ◽  
Previous Version

The present state of astrometric, spectroscopic and photometric data for stars in 63 open clusters nearer to the Sun than 750 pc is summarized. Table I reports the limits of the available data in terms of the apparent V magnitude, in the same way as the previous version (Mermilliod 1977). Information on the apparent V magnitude of the brightest main sequence star (Vbr) and on the number of stars brighter than V=10 (n∗) has been included. In addition, the bluest spectral type on the main sequence has been used as an age estimator (TS).

scholarly journals A precise asteroseismic age and metallicity for HD 139614: a pre-main-sequence star with a protoplanetary disc in Upper Centaurus–Lupus

2021 ◽  
Vol 502 (2) ◽  
pp. 1633-1646
Author(s):  
Simon J Murphy ◽  
Meridith Joyce ◽  
Timothy R Bedding ◽  
Timothy R White ◽  
Mihkel Kama
Keyword(s):  
Main Sequence ◽  
Main Sequence Star ◽  
Radial Pulsation ◽  
Chemical Abundance ◽  
Abundance Pattern ◽  
Intermediate Mass Stars ◽  
Metal Abundance ◽  
Ring Structures ◽  
Stellar Oscillation

ABSTRACT HD 139614 is known to be a ∼14-Myr-old, possibly pre-main-sequence star in the Sco-Cen OB association in the Upper Centaurus-Lupus subgroup, with a slightly warped circumstellar disc containing ring structures hinting at one or more planets. The star’s chemical abundance pattern is metal-deficient except for volatile elements, which places it in the λ Boo class and suggests it has recently accreted gas-rich but dust-poor material. We identify seven dipole and four radial pulsation modes among its δ Sct pulsations using the TESS light curve and an échelle diagram. Precision modelling with the mesa stellar evolution and gyre stellar oscillation programs confirms it is on the pre-main sequence. Asteroseismic, grid-based modelling suggests an age of 10.75 ± 0.77 Myr, a mass of 1.52 ± 0.02 M ⊙, and a global metal abundance of Z = 0.0100 ± 0.0010. This represents the first asteroseismic determination of the bulk metallicity of a λ Boo star. The precise age and metallicity offer a benchmark for age estimates in Upper Centaurus–Lupus, and for understanding disc retention and planet formation around intermediate-mass stars.

GRAVITATIONAL THERMODYNAMICS AND BLACK-HOLE MERGERS

2000 ◽  
Vol 15 (30) ◽  
pp. 4871-4875 ◽  
Author(s):  
SIMON F. PORTEGIES ZWART ◽  
STEPHEN L. W. MCMILLAN
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Neutron Star ◽  
Gravitational Waves ◽  
Star Clusters ◽  
Black Hole Binaries ◽  
Orbital Periods ◽  
Binary Evolution ◽  
Event Rates ◽  
Gravitational Thermodynamics

Black holes become the most massive objects early in the evolution of star clusters. Dynamical relaxation then causes them to sink to the cluster core, where they form binaries which become more tightly bound by superelastic encounters with other cluster members. Ultimately, these binaries are ejected from the cluster. The majority of escaping black-hole binaries have orbital periods short enough and eccentricities high enough that the emission of gravitational waves causes them to coalesce within a few billion years. The rate at which such collisions occur is on the order of 10-7 per year per cubic megaparsec. This implies event rates for gravitational-wave detectors substantially greater than current estimates of the corresponding rates from neutron-star mergers or black-hole mergers stemming from pure binary evolution.

scholarly journals Spatial Structure of Star Clusters by the 2MASS Database

2001 ◽  
Vol 183 ◽  
pp. 331-332
Author(s):  
J.W. Chen ◽  
W.P. Chen
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Star Clusters ◽  
Young Star ◽  
Open Clusters ◽  
Main Sequence Stars ◽  
Giant Stars ◽  
Sky Survey ◽  
Mass Segregation ◽  
Young Star Clusters

AbstractWe present some results of a pilot program to study star clusters with the Two-Micron All-Sky Survey (2MASS) observations. While 2MASS cannot resolve the cores or detect much of the main sequence of globular clusters, the homogeneity and large angular coverages make the database suitable to study young star clusters. We show that member stars are centrally concentrated in open clusters, with a density distribution markedly shallower than that for globular clusters. In NGC2506 (age 3 Gyr) giant stars appear to occupy a smaller region than main sequence stars—a natural consequence of mass segregation.

scholarly journals Chemical Abundance Signature of J0023+0307: A Second-generation Main-sequence Star with [Fe/H] < −6

2019 ◽  
Vol 871 (2) ◽  
pp. 146 ◽  
Author(s):  
Anna Frebel ◽  
Alexander P. Ji ◽  
Rana Ezzeddine ◽  
Terese T. Hansen ◽  
Anirudh Chiti ◽  
...  
Keyword(s):  
Second Generation ◽  
Main Sequence ◽  
Main Sequence Star ◽  
Chemical Abundance
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