scholarly journals IRAS 22150+6109 – a young B-type star with a large disc

2018 ◽  
Vol 477 (1) ◽  
pp. 977-982 ◽  
Author(s):  
Olga V Zakhozhay ◽  
Anatoly S Miroshnichenko ◽  
Kenesken S Kuratov ◽  
Vladimir A Zakhozhay ◽  
Serik A Khokhlov ◽  
...  
Keyword(s):  
Type Star ◽  
Large Disc

Symbiotic Stars at Optical, Infrared and Radio Wavelengths

1979 ◽  
Vol 46 ◽  
pp. 125-149 ◽  
Author(s):  
David A. Allen
Keyword(s):  
Temperature Regime ◽  
Type Star ◽  
Stellar Systems ◽  
Symbiotic Stars ◽  
Lower Excitation ◽  
Definition Of ◽  
Original Type

No paper of this nature should begin without a definition of symbiotic stars. It was Paul Merrill who, borrowing on his botanical background, coined the termsymbioticto describe apparently single stellar systems which combine the TiO absorption of M giants (temperature regime ≲ 3500 K) with He II emission (temperature regime ≳ 100,000 K). He and Milton Humason had in 1932 first drawn attention to three such stars: AX Per, CI Cyg and RW Hya. At the conclusion of the Mount Wilson Ha emission survey nearly a dozen had been identified, and Z And had become their type star. The numbers slowly grew, as much because the definition widened to include lower-excitation specimens as because new examples of the original type were found. In 1970 Wackerling listed 30; this was the last compendium of symbiotic stars published.

scholarly journals Formation rate of LB-1-like systems through dynamical interactions

2020 ◽  
Vol 72 (3) ◽  
Author(s):  
Ataru Tanikawa ◽  
Tomoya Kinugawa ◽  
Jun Kumamoto ◽  
Michiko S Fujii
Keyword(s):  
Open Cluster ◽  
Formation Rate ◽  
Open Clusters ◽  
Type Star ◽  
Dynamical Mechanism ◽  
Milky Way Galaxy ◽  
Triple Systems ◽  
Stellar Collisions ◽  
Solar Metallicity ◽  
Helium Star

Abstract We estimate formation rates of LB-1-like systems through dynamical interactions in the framework of the theory of stellar evolution before the discovery of the LB-1 system. The LB-1 system contains a ∼70 ${M_{\odot}}$ black hole (BH), a so-called pair instability (PI) gap BH, and a B-type star with solar metallicity, and has nearly zero eccentricity. The most efficient formation mechanism is as follows. In an open cluster, a naked helium star (with ∼20 ${M_{\odot}}$) collides with a heavy main sequence star (with ∼50 ${M_{\odot}}$) which has a B-type companion. The collision results in a binary consisting of the collision product and the B-type star with a high eccentricity. The binary can be circularized through the dynamical tide with radiative damping of the collision product envelope. Finally, the collision product collapses to a PI-gap BH, avoiding pulsational pair instability and pair instability supernovae because its He core is as massive as the pre-colliding naked He star. We find that the number of LB-1-like systems in the Milky Way galaxy is ∼0.01(ρoc/104 ${M_{\odot}}$ pc−3), where ρoc is the initial mass densities of open clusters. If we take into account LB-1-like systems with O-type companion stars, the number increases to ∼0.03(ρoc/104 ${M_{\odot}}$ pc−3). This mechanism can form LB-1-like systems at least ten times more efficiently than the other mechanisms: captures of B-type stars by PI-gap BHs, stellar collisions between other types of stars, and stellar mergers in hierarchical triple systems. We conclude that no dynamical mechanism can explain the presence of the LB-1 system.

scholarly journals Chemical Composition of the RS CNn-Type Star 33 Piscium

2011 ◽  
Vol 20 (1) ◽  
Author(s):  
G. Barisevišius ◽  
G. Tautvaišienė ◽  
S. Berdyugina ◽  
Y. Chorniy ◽  
I. Ilyin
Keyword(s):  
Chemical Composition ◽  
Chemical Elements ◽  
Type Star

AbstractAbundances of 22 chemical elements, including the key elements and isotopes such as

KIC 7732964 – A Possible Candidate FK Com-Type Star

Astrophysics ◽  
2021 ◽  
Author(s):  
E. S. Dmitrienko ◽  
I. S. Savanov ◽  
V. B. Puzin
Keyword(s):  
Type Star

scholarly journals Data reduction and calibration for LAMOST survey

2013 ◽  
Vol 9 (S298) ◽  
pp. 428-428 ◽  
Author(s):  
Ali Luo ◽  
Jiannan Zhang ◽  
Jianjun Chen ◽  
Yihan Song ◽  
Yue Wu ◽  
...  
Keyword(s):  
Data Reduction ◽  
Effective Temperature ◽  
Type Star ◽  
First Year ◽  
General Survey ◽  
Analysis Pipeline ◽  
Spectra Analysis ◽  
Pilot Survey ◽  
Fitting Method ◽  
Data Policy

AbstractThere are three data pipelines for LAMOST survey. The raw data is reduced to one dimension spectra by the data reduction pipeline(2D pipeline), the extracted spectra are classified and measured by the spectral analysis pipeline(1D pipeline), while stellar parameters are measured by LASP pipeline.(a) The data reduction pipeline. The main tasks of the data reduction pipeline include bias calibration, flat field, spectra extraction, sky subtraction, wavelength calibration, exposure merging and wavelength band connection.(b) The spectra analysis pipeline. This pipeline is designed to classify and identify objects from the extracted spectra and to measure their redshift (or radial velocity). The PCAZ (Glazebrook et al. 1998) method is applied to do the classification and redshift measurement.(c) Stellar parameters LASP. Stellar parameters pipeline (LASP) is to estimate stellar atmospheric parameters, e.g. effective temperature Teff, surface gravity log g, and metallicity [Fe/H], for F, G and K type stars. To effectively determine those fundamental stellar measurements, three steps with different methods are employed. The first step utilizes the line indices to approximately define the effective temperature range of the analyzed star. Secondly, a set of the initial approximate values of the three parameters are given based on template fitting method. Finally, we exploit ULySS (Koleva et al. 2009) to give the final values of parameters through minimizing the χ 2 value between the observed spectrum and a multidimensional grid of model spectra which is generated by an interpolating of ELODIE library. There are two other classification for A type star and M type star. For A type star, standard MK system is employed (Gray et al. 2009) to give each object temperature class and luminosity type. For M type star, they are classified into subclasses by an improved Hammer method, and metallicity of each objects is also given.During the pilot survey, algorithms were improved and the pipelines were tested. The products of LAMOST survey will include extracted and calibrated spectra in FITS format, a catalog of FGK stars with stellar parameters, a catalog of M dwarf with subclass and metallicity, and a catalog of A type star with MK classification. A part of the pilot survey data, including about 319 000 high quality spectra with SNR > 10, a catalog of stellar parameters of FGK stars and another catalog of a subclass of M type stars have been released to the public in August 2012 (Luo et al. 2012). The general survey started from October 2012, and completed the first year survey. The formal data release one (DR1) is being prepared, which will include both pilot survey and first year general survey, and planed to be released under the LAMOST data policy.

scholarly journals Seismic modelling of the rotating, slowly pulsating B-type star HD 21071

2015 ◽  
Vol 453 (1) ◽  
pp. 277-286 ◽  
Author(s):  
W. Szewczuk ◽  
J. Daszyńska-Daszkiewicz
Keyword(s):  
Type Star ◽  
Seismic Modelling

scholarly journals Forming a large disc galaxy from az< 1 major merger

2009 ◽  
Vol 398 (1) ◽  
pp. 312-320 ◽  
Author(s):  
F. Governato ◽  
C. B. Brook ◽  
A. M. Brooks ◽  
L. Mayer ◽  
B. Willman ◽  
...  
Keyword(s):  
Disc Galaxy ◽  
Large Disc ◽  
Major Merger

The high-galactic-latitude O-type star HD 93521

1977 ◽  
Vol 48 (2) ◽  
pp. 483-489 ◽  
Author(s):  
Margherita Hack ◽  
Nihal Yilmaz
Keyword(s):  
Type Star ◽  
Galactic Latitude ◽  
High Galactic Latitude

scholarly journals First Detection of Period Doubling in a BL Herculis Type Star: Observations and Theoretical Models

2012 ◽  
pp. 85-89
Author(s):  
R. Smolec ◽  
I. Soszyński ◽  
P. Moskalik ◽  
A. Udalski ◽  
M. K. Szymański ◽  
...  
Keyword(s):  
Period Doubling ◽  
Theoretical Models ◽  
Type Star
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