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Single star evolution does not allow extremely low-mass stars to cross the classical instability strip (IS) during the Hubble time. However, within binary evolution framework low-mass stars can appear inside the IS once the mass transfer…

Solar and Stellar Astrophysics · Physics 2017-01-25 P. Karczmarek , G. Wiktorowicz , K. Iłkiewicz , R. Smolec , K. Stępień , G. Pietrzyński , W. Gieren , K. Belczynski

The stars within our Galactic halo presents a snapshot of its ongoing growth and evolution, probing galaxy formation directly. Here, we present our first analysis of the stellar halo from detailed maps of Blue Horizontal Branch (BHB) stars…

Astrophysics of Galaxies · Physics 2018-08-01 Zhen Wan , Prajwal R. Kafle , Geraint F. Lewis , Dougal Mackey , Sanjib Sharma , Rodrigo A. Ibata

The observed lithum (Li) abundance of Galactic halo stars mainly fall within the range of 2.0--2.4 dex. This nearly constant value, known as the Spite plateau, is approximately a factor of three lower than the value predicted from cosmic…

Solar and Stellar Astrophysics · Physics 2026-02-27 Wuming Yang , Shuya Dou , Xiangcun Meng , Yaqian Wu , Shaolan Bi

The discovery of a binary comprising a black hole (BH) and a millisecond pulsar (MSP) would yield insights into stellar evolution and facilitate exquisitely sensitive tests of general relativity. Globular clusters (GCs) are known to harbor…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Drew Clausen , Steinn Sigurdsson , David F. Chernoff

The discovery of extended gamma-ray emission toward a number of middle-aged pulsars suggests the possibility of long-lived particle confinement beyond the classical pulsar wind nebula (PWN) stage. How this emerging source class can be…

High Energy Astrophysical Phenomena · Physics 2022-10-05 Pierrick Martin , Luigi Tibaldo , Alexandre Marcowith , Soheila Abdollahi

Context. Recent astrometric and spectroscopic surveys of OB stars have revealed a few stellar-mass black holes (BHs) with orbital periods as low as 10 days. No X-ray counterpart has been detected, due to the absence of a radiatively…

High Energy Astrophysical Phenomena · Physics 2024-10-23 Koushik Sen , Ileyk El Mellah , Norbert Langer , Xiao-Tian Xu , Martin Quast , Daniel Pauli

Galactic white dwarf binaries (WDBs) and black hole binaries (BHBs) will be gravitational wave (GW) sources for LISA. Their detection will provide insights into binary evolution and the evolution of our Galaxy through cosmic history. Here,…

Astrophysics of Galaxies · Physics 2024-10-24 Petra Tang , Jan Eldridge , Renate Meyer , Astrid Lamberts , Guillaume Boileau , Wouter van Zeist

If confirmed, a wide binary system of 70 $M_{\odot}$ black hole (BH) and an 8 $M_{\odot}$ main sequence star (LB-1) is observed to reside in the Milky Way (MW). We show that long term evolution of an 8 $M_{\odot}$ star around a BH with mass…

High Energy Astrophysical Phenomena · Physics 2020-10-07 Mohammadtaher Safarzadeh , Enrico Ramirez-Ruiz , Charles Kilpatrick

Excitation of radial oscillations in population I (X=0.7, Z=0.02) red supergiants is investigated using the solution of the equations of radiation hydrodynamics and turbulent convection. The core helium burning stars with masses 8M_odot <=…

Solar and Stellar Astrophysics · Physics 2015-06-03 Yuri A. Fadeyev

Stellar evolution calculations to the stage of the cooling white dwarf were done for population~I stars with masses on the main sequence $1M_\odot\le M_0\le 1.5M_\odot$. The final helium flash LTP is shown to occur in post--AGB stars with…

Solar and Stellar Astrophysics · Physics 2019-12-03 Yu. A. Fadeyev

Recent pieces of evidence have revealed that most, and possibly all, globular star clusters are composed of groups of stars that formed in multiple episodes with different chemical compositions. In this sense, it has also been argued that…

Astrophysics of Galaxies · Physics 2015-06-18 A. A. R. Valcarce , M. Catelan , J. Alonso-García , C. Cortés , J. R. De Medeiros

To investigate the asymptotic giant branch (AGB) population in the Galactic halo, we search for pulsating AGB stars at a heliocentric distance over 50kpc. Our research is based on the Catalina Southern Survey (CSS) catalogue of variables,…

Astrophysics of Galaxies · Physics 2021-06-30 Nicolas Mauron , Kamo S. Gigoyan , Tim R. Kendall , Kelly M. Hambleton

The Milky Way in-situ halo, also known as the Splash, consists of old (Age $>$ 10 Gyr), metal-rich ([Fe/H] $> -0.7$), high-$\alpha$ stars, i.e., thick disk-like chemistry, on halo-like orbits (eccentricity > 0.6). Its origin is linked to…

Preflare activities contain critical information about the pre-cursors and causes of solar eruptions. Here we investigate the characteristics and origin of a group of broadband pulsations (BBPs) in the decimetric-metric wavelengths, taking…

Solar and Stellar Astrophysics · Physics 2023-06-14 Maoshui Lv , Baolin Tan , Ruisheng Zheng , Zhao Wu , Bing Wang , Xiangliang Kong , Yao Chen

We report the results of a long-term spectroscopic monitoring of the A-type supergiant with the B[e] phenomenon 3 Pup = HD 62623. We confirm earlier findings that it is a binary system. The orbital parameters were derived using…

This is the third paper of a series dedicated to the study of the star formation rates, star formation histories, metallicities and dust contents of a sample of blue compact galaxies (BCGs). We constrain the stellar contents of 73 blue…

Astrophysics · Physics 2009-11-07 Xu Kong , Stephane Charlot , Achim Weiss , Fuzhen Cheng

We have used millisecond pulsars (MSPs) from the southern High Time Resolution Universe (HTRU) intermediate latitude survey area to simulate the distribution and total population of MSPs in the Galaxy. Our model makes use of the scale…

We present the stellar density profile of the outer halo of the Galaxy traced over a range of Galactocentric radii from $15< R_{GC} < 220$ kpc by blue horizontal branch (BHB) stars. These stars are identified photometrically using deep…

We characterize the population of blue horizontal-branch (BHB) stars in the bulge-halo transition region of the Milky Way using the VISTA Variables in the V\'ia L\'actea (VVV) ESO Public Survey data. The selection of BHB stars is made using…

Solar and Stellar Astrophysics · Physics 2019-03-06 Katherine Montenegro , Dante Minniti , Javier Alonso-García , Maren Hempel , Roberto K. Saito , Timothy C. Beers , David Brown

A stellar common envelope occurs in a binary system when the atmosphere of an evolving star expands to encompass an orbiting companion object. Such systems are predicted to evolve rapidly, ejecting the stellar envelope and leaving the…