2017ApJ...842..123F


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.28CET11:45:58

2017ApJ...842..123F - Astrophys. J., 842, 123-123 (2017/June-3)

Age spreads and the temperature dependence of age estimates in Upper Sco.

FANG Q., HERCZEG G.J. and RIZZUTO A.

Abstract (from CDS):

Past estimates for the age of the Upper Sco Association are typically 11-13 Myr for intermediate-mass stars and 4-5 Myr for low-mass stars. In this study, we simulate populations of young stars to investigate whether this apparent dependence of estimated age on spectral type may be explained by the star formation history of the association. Solar and intermediate mass stars begin their pre-main sequence evolution on the Hayashi track, with fully convective interiors and cool photospheres. Intermediate-mass stars quickly heat up and transition onto the radiative Henyey track. As a consequence, for clusters in which star formation occurs on a timescale similar to that of the transition from a convective to a radiative interior, discrepancies in ages will arise when ages are calculated as a function of temperature instead of mass. Simple simulations of a cluster with constant star formation over several Myr may explain about half of the difference in inferred ages versus photospheric temperature; speculative constructions that consist of a constant star formation followed by a large supernova-driven burst could fully explain the differences, including those between F and G stars where evolutionary tracks may be more accurate. The age spreads of low-mass stars predicted from these prescriptions for star formation are consistent with the observed luminosity spread of Upper Sco. The conclusion that a lengthy star formation history will yield a temperature dependence in ages is expected from the basic physics of pre-main sequence evolution, and is qualitatively robust to the large uncertainties in pre-main sequence evolutionary models.

Abstract Copyright: © 2017. The American Astronomical Society. All rights reserved.

Journal keyword(s): stars: evolution - stars: formation - stars: pre-main sequence - stars: pre-main sequence

Simbad objects: 18

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Number of rows : 18

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME THA As* 00 00 -62.0           ~ 324 0
2 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 2928 0
3 NAME Taurus Dark Cloud SFR 04 41.0 +25 52           ~ 3360 0
4 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 1924 1
5 * eta Cha * 08 41 19.5144242735 -78 57 48.102318990 5.02 5.351 5.453     B8V 209 0
6 NAME TW Hya Association As* 11 01.9 -34 42           ~ 801 0
7 NAME Cha Dark Cloud SFR 11 55 -78.0           ~ 536 1
8 * eps Cha * 11 59 37.57634 -78 13 18.6179   4.869 4.916     B9V(n) 93 1
9 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 338 1
10 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 534 0
11 NAME Upper Centaurus Lupus As* 15 24 -41.9           ~ 345 1
12 HD 142361 TT* 15 54 59.8690406838 -23 47 18.187188652   9.68 8.960   8.092 G3V 68 0
13 HD 142989 ** 15 58 29.3048238096 -21 24 03.994931861   9.55 9.10     F2/3IV/V 22 1
14 NAME Upper Sco Association As* 16 12 -23.4           ~ 972 1
15 2MASS J16123604-2723031 Y*O 16 12 36.0528093605 -27 23 02.978477029   13.18 11.21     K4.0e 6 0
16 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1088 1
17 * rho Oph ** 16 25 35.11766 -23 26 49.8150 4.30 4.85 4.63 4.27 3.96 B2IV+B2V 594 2
18 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 2964 0

    Equat.    Gal    SGal    Ecl

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2020.01.28-11:45:58

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