scholarly journals What Can Pre-Main Sequence Binary Star Populations Tell Us about Binary Formation Mechanisms?

2001 ◽  
Vol 200 ◽  
pp. 210-218 ◽  
Author(s):  
Andrea M. Ghez
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Main Sequence ◽  
Binary Star ◽  
Open Clusters ◽  
Formation Mechanisms ◽  
Primary Star ◽  
Binary Formation ◽  
Review Current ◽  
Made In

We review current observations of binary star populations with particular attention to what insight these populations can give us into the problem of how binary stars form. Significant progress has been made in the past few years, revealing variations as a function of site, primary star mass, and binary star separations. The variations in the binary star population with type of star formation site in comparison with the field, suggests that ∼30% of the field binaries formed in loose T associations and ∼70% formed in the dense progenitors of open clusters. Variations with mass and separation on the whole are well matched by the predictions of fragmentation followed by competitive accretion. However, there remains much work to be done on both the observational and theoretical end before a complete picture of binary star formation can be developed.

scholarly journals Binary Star Formation Simulations

2011 ◽  
Vol 7 (S282) ◽  
pp. 409-416
Author(s):  
C. J. Clarke
Keyword(s):  
Star Formation ◽  
Magnetic Fields ◽  
Binary Stars ◽  
Binary Star ◽  
Statistical Properties ◽  
Future Research ◽  
Mass Ratio ◽  
Theoretical Comparison ◽  
Wide Pairs ◽  
Binary Formation

AbstractBinary stars provide an excellent calibration of the success or otherwise of star formation simulations, since the reproduction of their statistical properties can be challenging. Here, I summarise the direction that the field has taken in recent years, with an emphasis on binary formation in the cluster context, and discuss which observational diagnostics are most ripe for meaningful theoretical comparison. I focus on two issues: the prediction of binary mass ratio distributions and the formation of the widest binaries in dissolving clusters, showing how in the latter case the incidence of ultra-wide pairs constrains the typical membership number of natal clusters to be of order a hundred. I end by drawing attention to recent works that include magnetic fields and which will set the direction of future research in this area.

scholarly journals A binary star formation mechanism through the fragmentation of prolate dense cores rotating end over end

1991 ◽  
Vol 147 ◽  
pp. 526-528
Author(s):  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Formation Mechanism ◽  
Binary Stars ◽  
Binary Star ◽  
Initial Structure ◽  
Eccentric Orbit ◽  
Dense Cores ◽  
Molecular Core ◽  
Low Mass

I propose and briefly elaborate on a major new mechanism for the formation of wide, low-mass binary stars: the fragmentation of a collapsing, initially elongated dense molecular core rotating end over end. This initial structure will develop into two independent gravitationally bound stellar condensations orbiting each other in a rather eccentric orbit.

scholarly journals A binary star formation mechanism through the fragmentation of prolate dense cores rotating end over end

1991 ◽  
Vol 147 ◽  
pp. 526-528
Author(s):  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Formation Mechanism ◽  
Binary Stars ◽  
Binary Star ◽  
Initial Structure ◽  
Eccentric Orbit ◽  
Dense Cores ◽  
Molecular Core ◽  
Low Mass

I propose and briefly elaborate on a major new mechanism for the formation of wide, low-mass binary stars: the fragmentation of a collapsing, initially elongated dense molecular core rotating end over end. This initial structure will develop into two independent gravitationally bound stellar condensations orbiting each other in a rather eccentric orbit.

scholarly journals Astronomy in Uzbekistan

2001 ◽  
Vol 24 (3) ◽  
pp. 231-232
Author(s):  
Sabit P. Ilyasov
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Solar Physics ◽  
Open Clusters ◽  
Image Motion ◽  
Close Binary ◽  
Atmospheric Conditions ◽  
Ccd Photometry ◽  
Close Binary Stars ◽  
Star Formation Regions

Ulugh Beg Astronomical Institute (UBAI) of the Uzbek Academy of Sciences is one of the oldest scientific institutions not only in Uzbekistan, but in the whole of Central Asia as well. There are five departments in the institute. The main directions of research are solar physics, young non-stationary and close binary stars in star formation regions, satellite geodynamics, non-linear and non-stationary evolution of galaxies. Helioseismology studies carried out in the frame of the IRIS (International Research on the Interior of the Sun) and TON (Taiwan Oscillation Network) projects. Astrophysical programmes such as a search for periodicity in star-formation regions, study of close binary stars in the same regions, as well as in open clusters, CCD photometry of extra-galactic objects as gravitation lenses have been made at the Maidanak Observatory, which is located in the south-east of Uzbekistan. Monitoring of the seeing at Mt. Maidanak from 1996 to 1999, using ESO Differential Image Motion Monitor, showed that its atmospheric conditions are comparable with the best international observatories. The present status of the main fields of research and prospects are discussed. (Co-author is Shurat A. Ehgamberdiev, Uzbekistan.)

scholarly journals The single-sided pulsator CO Camelopardalis

2020 ◽  
Vol 494 (4) ◽  
pp. 5118-5133 ◽  
Author(s):  
D W Kurtz ◽  
G Handler ◽  
S A Rappaport ◽  
H Saio ◽  
J Fuller ◽  
...  
Keyword(s):  
Binary Stars ◽  
Binary Star ◽  
Spectral Energy Distribution ◽  
Radial Velocities ◽  
Close Binary ◽  
Theoretical Modelling ◽  
Spectral Energy ◽  
Primary Star ◽  
Pulsating Stars ◽  
Secondary Star

ABSTRACT CO Cam (TIC 160268882) is the second ‘single-sided pulsator’ to be discovered. These are stars where one hemisphere pulsates with a significantly higher amplitude than the other side of the star. CO Cam is a binary star comprised of an Am δ Sct primary star with Teff = 7070 ± 150 K, and a spectroscopically undetected G main-sequence secondary star. The dominant pulsating side of the primary star is centred on the L1 point. We have modelled the spectral energy distribution combined with radial velocities, and independently the TESS light curve combined with radial velocities. Both of these give excellent agreement and robust system parameters for both stars. The δ Sct star is an oblique pulsator with at least four low radial overtone (probably) f modes with the pulsation axis coinciding with the tidal axis of the star, the line of apsides. Preliminary theoretical modelling indicates that the modes must produce much larger flux perturbations near the L1 point, although this is difficult to understand because the pulsating star does not come near to filling its Roche lobe. More detailed models of distorted pulsating stars should be developed. These newly discovered single-sided pulsators offer new opportunities for astrophysical inference from stars that are oblique pulsators in close binary stars.

scholarly journals Fragile Binaries: Observational Leverage on Difficult Astrophysical Problems

2006 ◽  
Vol 2 (S240) ◽  
pp. 300-305
Author(s):  
T.D. Oswalt ◽  
K.B. Johnston ◽  
M. Rudkin ◽  
T. Vaccaro ◽  
D. Valls-Gabaud
Keyword(s):  
Binary Stars ◽  
White Dwarfs ◽  
Main Sequence ◽  
Age Determination ◽  
Open Clusters ◽  
Mass Relation ◽  
Space Motion ◽  
Sequence Components ◽  
Determination Methods ◽  
Cool White Dwarfs

AbstractLoosely bound,fragilebinary stars, whose separations may reach ∼ 0.1 pc, are like open clusters with two coeval components. They provide a largely overlooked avenue for the investigation of many astrophysical questions. For example, the orbital distribution of fragile binaries with two long-lived main-sequence components provides a sensitive test of the cumulative effects of the Galactic environment. In pairs where one component is evolved, the orbits have been amplified by post-main-sequence mass loss, potentially providing useful constraints on the initial-to-final mass relation for white dwarfs. The nearly featureless spectra of cool white dwarfs usually provide little information about intrinsic radial velocity, full space motion, population membership, metallicity, etc. However, distant main sequence companions provide benchmarks against which those properties can be determined. In addition, the cooling ages of white dwarf components provide useful limits on the ages of their main sequence companions, independent of other stellar age determination methods. This paper summarizes some of the ways fragile binaries provide useful leverage on these and other problems of interest.

GRAVITATIONAL COLLAPSE AND FRAGMENTATION OF MOLECULAR CLOUD CORES

2001 ◽  
Vol 10 (02) ◽  
pp. 115-211 ◽  
Author(s):  
LEONARDO DI G. SIGALOTTI ◽  
JAIME KLAPP
Keyword(s):  
Star Formation ◽  
Binary Stars ◽  
Molecular Cloud ◽  
Main Sequence ◽  
Numerical Models ◽  
Present Theory ◽  
Main Sequence Stars ◽  
Consistent Manner ◽  
Cloud Cores ◽  
Observational Knowledge

The detected multiplicity of main-sequence and pre-main-sequence stars along with the emerging evidence for binary and multiple protostars, imply that stars may ultimately form by fragmentation of collapsing molecular cloud cores. These discoveries, coupled with recent observational knowledge of the structure of dense cloud cores and of the properties of young binary stars, provide serious constraints to the theory of star formation. Most theoretical progress in the field of star formation is largely based on numerical calculations of the early collapse and fragmentation of protostellar clouds. Although these models have been quite successful at predicting the formation of binary protostars, a direct comparison between theory and observations has not yet been established. The results of recent observations as well as of early and recent analytic and numerical models, on which the present theory of star formation is based, are reviewed here in a self-consistent manner.

scholarly journals What Can Observations of Young Binaries Tell Us about Binary Formation?

2001 ◽  
Vol 200 ◽  
pp. 346-360 ◽  
Author(s):  
Cathie J. Clarke
Keyword(s):  
Main Sequence ◽  
Binary Star ◽  
Spectral Energy ◽  
Strong Impact ◽  
Energy Distributions ◽  
Star Forming ◽  
Star Forming Regions ◽  
Binary Formation ◽  
Future Task ◽  
Cloud Core

In this paper I discuss three areas in which observational data is likely to have a strong impact on theoretical ideas about binary star formation: the collation of binary statistics for different primary masses, the acquisition of spectral energy distributions for individual components within pre-main sequence binaries and the use of binary statistics to constrain the mix of star forming regions that must combine to form the field. Theoretical and observational work is ongoing in each of these areas. It is suggested that for observers an important future task is to remeasure the wide binary population among local field stars, whilst for theorists a problem yet to be addressed is how the mass of a molecular cloud core affects its binary fragmentation properties.

scholarly journals Modelling Early-type Stars in Eclipsing Binaries of Open Clusters: A New Method for Age Determination from the Ratio of Radii

2011 ◽  
Vol 28 (1) ◽  
pp. 66-76 ◽  
Author(s):  
M. Yıldız
Keyword(s):  
Binary Systems ◽  
Main Sequence ◽  
Age Determination ◽  
Primary Component ◽  
Open Clusters ◽  
Eclipsing Binaries ◽  
Primary Star ◽  
Fundamental Properties ◽  
Sources Of Knowledge ◽  
The Difference

AbstractBinary systems, in particular eclipsing binaries, are essential sources of knowledge of the fundamental properties of stars. The ages of binaries, members of open clusters, are constrained by their own fundamental properties and by those of the hosting cluster. The ages of eleven open clusters are here found by constructing models for the components of twelve eclipsing binaries. The difference between the ages we find and the ages of the clusters derived from isochrone fitting is up to 40%. For the binary system V497 Cep in NGC 7160, the difference is about 100%. Binary systems whose primary component is about to complete its main-sequence lifetime, such as V453 Cyg and V906 Sco, are the most suitable systems for age determination. Using model results for these stars, we derive an expression for sensitive and uncomplicated relative age determination of binary systems (age divided by the main-sequence lifetime of the primary star). The expression is given as a logarithm of radii ratio divided by a logarithm of mass ratio. Two advantages of this expression are that: (i) it is nearly independent of the assumed chemical composition of the models because of the appearance of the ratio of radii; and (ii) the ratios of radii and masses are observationally much more precise than their absolute values. We also derive another expression using luminosities rather than radii and compare results.

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