The effect of screening factors and thermonuclear reaction rates in the pre-main sequence evolution of low mass stars

2010 ◽  
Vol 31 (3) ◽  
pp. 135-145
Author(s):  
İ. Küçük ◽  
Ş. Çalışkan
Keyword(s):  
Main Sequence ◽  
Reaction Rates ◽  
Sequence Evolution ◽  
Thermonuclear Reaction ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals The rotational evolution of young low mass stars

2007 ◽  
Vol 3 (S243) ◽  
pp. 231-240 ◽  
Author(s):  
Jérôme Bouvier
Keyword(s):  
Angular Momentum ◽  
Accretion Disk ◽  
Main Sequence ◽  
Young Stars ◽  
Sequence Evolution ◽  
Main Sequence Stars ◽  
Low Mass Stars ◽  
Rotational Evolution ◽  
Low Mass

AbstractStar-disk interaction is thought to drive the angular momentum evolution of young stars. In this review, I present the latest results obtained on the rotational properties of low mass and very low mass pre-main sequence stars. I discuss the evidence for extremely efficient angular momentum removal over the first few Myr of pre-main sequence evolution and describe recent results that support an accretion-driven braking mechanism. Angular momentum evolution models are presented and their implication for accretion disk lifetimes discussed.

scholarly journals Effect of mass gain on stellar evolution

1981 ◽  
Vol 59 ◽  
pp. 361-371
Author(s):  
R. Ebert ◽  
H. Zinnecker
Keyword(s):  
Stellar Evolution ◽  
Main Sequence ◽  
Accretion Rate ◽  
Mass Gain ◽  
Point Mass ◽  
Sequence Evolution ◽  
Main Sequence Stars ◽  
Low Mass Stars ◽  
Low Mass ◽  
Cloud Material

AbstractIn this paper we present a fully hydrodynamical treatment of the stationary isothermal accretion problem onto a moving gravitating point mass. The derivation is purely analytical. We find that the accretion rate is more than a factor of 50 higher than the accretion rate derived from the partially non-hydrodynamical treatment by Hoyle and Lyttleton (1939) or Bondi and Hoyle (1944). This result may have some bearing on the evolutionary tracks of young pre-Main Sequence stars still embedded in their parent protocluster cloud. We discuss the work by Federova (1979) who investigated the pre-Main Sequence evolution of degenerate low mass ‘stars’ with strong accretion of protocluster cloud material. We suggest that the stars which lie below the Main Sequence in young clusters could strongly accrete matter at the pre-Main Sequence stage.

scholarly journals X-Ray Emission from Distant Stellar Clusters

1998 ◽  
Vol 188 ◽  
pp. 220-221
Author(s):  
N.S. Schulz ◽  
J.H. Kastner
Keyword(s):  
Main Sequence ◽  
Sequence Evolution ◽  
Late Type ◽  
Low Mass Stars ◽  
Dwarf Stars ◽  
X Ray ◽  
T Tauri ◽  
Low Mass ◽  
M Stars ◽  
M Dwarf Stars

Observations with the Einstein Observatory indicated that stellar X-ray activity diminishes in clusters older than 70 Myr (Pleiades). ROSAT observations of older clusters also support this result (see Caillault 1995 and references therein). The timescales over which young stars diminish in X-ray luminosity depends on spectral type (Randich et al. 1996), leading to the conclusion that X-ray activity in late type PMS depends on age and stellar mass. F and G-stars approach the main sequence much faster and the diminishing rates of X-ray activity from F to M stars start to differ considerably. Kastner et al. (1997) observed that the mean of the ratio Lx/Lbol for K and M dwarf stars increases monotonically for low-mass stars from the very early T Tauri stage through the age of the Pleiades cluster, reflecting the contraction and spin-up of such stars during pre-main sequence evolution. This ratio then decreases towards middle aged stars, as late-type main sequence stars spin down. Here we extend this result by including more distant clusters that are younger overall than those considered by Kastner et al. and also including earlier spectral types.

Pre-Main-Sequence evolution of rotating low-mass stars

1989 ◽  
Vol 154 (2) ◽  
pp. 255-269 ◽  
Author(s):  
Nilgün Kiziloğlu
Keyword(s):  
Main Sequence ◽  
Sequence Evolution ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals Effect of accretion on the pre-main-sequence evolution of low-mass stars and brown dwarfs

2017 ◽  
Vol 605 ◽  
pp. A77 ◽  
Author(s):  
Eduard I. Vorobyov ◽  
Vardan Elbakyan ◽  
Takashi Hosokawa ◽  
Yuya Sakurai ◽  
Manuel Guedel ◽  
...  
Keyword(s):  
Main Sequence ◽  
Brown Dwarfs ◽  
Sequence Evolution ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals Early and Main Sequence Evolution of Low-Mass Stars.

1966 ◽  
Vol 71 ◽  
pp. 384
Author(s):  
D. Ezer ◽  
A. G. W. Cameron
Keyword(s):  
Main Sequence ◽  
Sequence Evolution ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals New low-mass members of the Lupus 3 dark cloud: Further indications of pre-main-sequence evolution strongly affected by accretion

2003 ◽  
Vol 406 (3) ◽  
pp. 1001-1017 ◽  
Author(s):  
F. Comerón ◽  
M. Fernández ◽  
I. Baraffe ◽  
R. Neuhäuser ◽  
A. A. Kaas
Keyword(s):  
Main Sequence ◽  
Sequence Evolution ◽  
Dark Cloud ◽  
Low Mass

scholarly journals Globular clusters and the evolution of their multiple stellar populations

2015 ◽  
Vol 12 (S316) ◽  
pp. 328-333
Author(s):  
W. Chantereau ◽  
C. Charbonnel ◽  
G. Meynet
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Chemical Properties ◽  
Stellar Populations ◽  
Chemical Compositions ◽  
Low Mass Stars ◽  
Sequence Band ◽  
Low Mass ◽  
Chemical Distribution ◽  
Host Stars

AbstractOur knowledge of the formation and early evolution of globular clusters (GCs) has been totally shaken with the discovery of the peculiar chemical properties of their long-lived host stars. Therefore, the interpretation of the observed Colour Magnitude Diagrams (CMD) and of the properties of the GC stellar populations requires the use of new stellar models computed with relevant chemical compositions. In this paper we use the grid of evolution models for low-mass stars computed by Chantereau et al. (2015) with the initial compositions of second-generation stars as predicted by the fast rotating massive stars scenario to build synthesis models of GCs. We discuss the implications of the assumed initial chemical distribution on 13 Gyr isochrones. We build population synthesis models to predict the fraction of stars born with various helium abundances in present day globular clusters (assuming an age of 13 Gyr). With the current assumptions, 61 % of stars on the main sequence are predicted to be born with a helium abundance in mass fraction, Yini, smaller than 0.3 and only 11 % have a Yini larger than 0.4. Along the horizontal branch, the fraction of stars with Yini inferior to 0.3 is similar to that obtained along the main sequence band (63 %), while the fraction of very He-enriched stars is significantly decreased (only 3 % with Yini larger than 0.38).

scholarly journals Asteroseismological Probing of the Thermal Evolution of White Dwarf Stars

1992 ◽  
Vol 9 ◽  
pp. 643-645
Author(s):  
G. Fontaine ◽  
F. Wesemael
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Main Sequence ◽  
Thermal Evolution ◽  
Sequence Evolution ◽  
Helium Burning ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
The Galaxy ◽  
Low Mass

AbstractIt is generally believed that the immediate progenitors of most white dwarfs are nuclei of planetary nebulae, themselves the products of intermediate- and low-mass main sequence evolution. Stars that begin their lifes with masses less than about 7-8 M⊙ (i.e., the vast majority of them) are expected to become white dwarfs. Among those which have already had the time to become white dwarfs since the formation of the Galaxy, a majority have burnt hydrogen and helium in their interiors. Consequently, most of the mass of a typical white dwarf is contained in a core made of the products of helium burning, mostly carbon and oxygen. The exact proportions of C and 0 are unknown because of uncertainties in the nuclear rates of helium burning.

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