scholarly journals Evolutionary Models for Low Mass Stars and Brown Dwarfs at Young Ages

2003 ◽  
Vol 211 ◽  
pp. 41-50 ◽  
Author(s):  
Isabelle Baraffe ◽  
Gilles Chabrier ◽  
France Allard ◽  
Peter Hauschildt
Keyword(s):  
Initial Conditions ◽  
Brown Dwarfs ◽  
Evolutionary Models ◽  
Low Mass Stars ◽  
Low Mass

We analyse evolutionary tracks at young ages for low mass stars with masses m ≤ 1.4 M⊙ and brown dwarfs down to one mass of Jupiter. We analyse current theoretical uncertainties due to initial conditions. Simple tests on initial conditions show the high uncertainties of models at ages ≲ 1 Myr.

scholarly journals The early evolution of low mass stars and brown dwarfs

2009 ◽  
Vol 5 (H15) ◽  
pp. 755-755
Author(s):  
Isabelle Baraffe
Keyword(s):  
Magnetic Field ◽  
Star Formation ◽  
Brown Dwarfs ◽  
Early Evolution ◽  
Evolutionary Models ◽  
Low Mass Stars ◽  
Low Mass ◽  
Effects Of Rotation ◽  
Star Formation Regions

My talk will focus on the early evolution of low mass objects. I will discuss the main uncertainties on current evolutionary models and the effects of rotation, magnetic field and early accretion history on young object's structure. I will also present possible solutions to the well known spread in HRD observed in star formation regions for objects of a few Myr old.

scholarly journals Peter Pan discs: finding Neverland’s parameters

2020 ◽  
Vol 496 (1) ◽  
pp. L111-L115
Author(s):  
Gavin A L Coleman ◽  
Thomas J Haworth
Keyword(s):  
Initial Conditions ◽  
Mass Star ◽  
Evolutionary Models ◽  
Peter Pan ◽  
Low Mass Stars ◽  
Star Forming ◽  
Star Forming Regions ◽  
Accretion Rates ◽  
Order Of Magnitude ◽  
Low Mass

ABSTRACT Peter Pan discs are a recently discovered class of long-lived discs around low-mass stars that survive for an order of magnitude longer than typical discs. In this paper, we use disc evolutionary models to determine the required balance between initial conditions and the magnitude of dispersal processes for Peter Pan discs to be primordial. We find that we require low transport (α ∼ 10−4), extremely low external photoevaporation (${\le}10^{-9}\, {\rm M}_{\odot }\, {\rm yr^{-1}}$), and relatively high disc masses (>0.25M*) to produce discs with ages and accretion rates consistent with Peter Pan discs. Higher transport (α = 10−3) results in disc lifetimes that are too short and even lower transport (α = 10−5) leads to accretion rates smaller than those observed. The required external photoevaporation rates are so low that primordial Peter Pan discs will have formed in rare environments on the periphery of low-mass star-forming regions, or deeply embedded, and as such have never subsequently been exposed to higher amounts of UV radiation. Given that such an external photoevaporation scenario is rare, the required disc parameters and accretion properties may reflect the initial conditions and accretion rates of a much larger fraction of the discs around low-mass stars.

scholarly journals Pre-Main Sequence Models for Low-Mass Stars and Brown Dwarfs

2001 ◽  
Vol 200 ◽  
pp. 483-491
Author(s):  
Isabelle Baraffe ◽  
Gilles Chabrier ◽  
France Allard ◽  
Peter Hauschildt
Keyword(s):  
Equation Of State ◽  
Main Sequence ◽  
Brown Dwarfs ◽  
Evolutionary Models ◽  
Recent Improvement ◽  
Low Mass Stars ◽  
Theory Equation ◽  
Low Mass

We present evolutionary models for young low mass stars (m ≤ 1M⊙) based on recent improvement of the theory: equation of state, atmosphere models, etc. We concentrate on early evolutionary phases from the initial deuterium burning phase to the zero-age Main Sequence. Evolutionary models for young brown dwarfs are also presented. We discuss the uncertainties of the present models. We analyse the difficulties arising when comparing models with observations for very young objects, in particular concerning the problem of reddening.

scholarly journals Evolutionary models for low-mass stars and brown dwarfs: Uncertainties and limits at very young ages

2002 ◽  
Vol 382 (2) ◽  
pp. 563-572 ◽  
Author(s):  
I. Baraffe ◽  
G. Chabrier ◽  
F. Allard ◽  
P. H. Hauschildt
Keyword(s):  
Brown Dwarfs ◽  
Evolutionary Models ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals Evolutionary Models for Very Low‐Mass Stars and Brown Dwarfs with Dusty Atmospheres

2000 ◽  
Vol 542 (1) ◽  
pp. 464-472 ◽  
Author(s):  
G. Chabrier ◽  
I. Baraffe ◽  
F. Allard ◽  
P. Hauschildt
Keyword(s):  
Brown Dwarfs ◽  
Evolutionary Models ◽  
Low Mass Stars ◽  
Low Mass

scholarly journals Primeval very low-mass stars and brown dwarfs – II. The most metal-poor substellar object

2017 ◽  
Vol 468 (1) ◽  
pp. 261-271 ◽  
Author(s):  
Z. H. Zhang 张曾华 ◽  
D. Homeier ◽  
D. J. Pinfield ◽  
N. Lodieu ◽  
H. R. A. Jones ◽  
...  
Keyword(s):  
Brown Dwarfs ◽  
Low Mass Stars ◽  
Low Mass
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