J/MNRAS/399/432 Fitted UBV magnitude for MS stars (Naylor+, 2009)
Are pre-main-sequence stars older than we thought?
Naylor T.
<Mon. Not. R. Astron. Soc., 399, 432-442 (2009)>
=2009MNRAS.399..432N 2009MNRAS.399..432N
ADC_Keywords: Models ; Clusters, open ; Stars, early-type ; Photometry, UBV
Keywords: methods: statistical - stars: early-type - stars: formation -
stars: fundamental parameters - stars: pre-main-sequence -
open clusters and associations: general
Abstract:
We fit the colour-magnitude diagrams of stars between the zero-age
main-sequence and terminal-age main sequence in young clusters and
associations. The ages we derive are a factor of 1.5-2 longer than
the commonly used ages for these regions, which are derived from the
positions of pre-main-sequence stars in colour-magnitude diagrams.
From an examination of the uncertainties in the main-sequence and
pre-main-sequence models, we conclude that the longer age scale is
probably the correct one, which implies that we must revise upwards
the commonly used ages for young clusters and associations. Such a
revision would explain the discrepancy between the observational
lifetimes of protoplanetary discs and theoretical calculations of the
time to form planets. It would also explain the absence of clusters
with ages between 5 and 30Myr.
Description:
To compare a set of ages derived from MS evolution with contraction
ages, we need a sample of clusters and associations which have
contraction ages, and for each of which data are available for MS
fitting. Our sample is, therefore, based on the groups we placed in
age order using the PMS in Mayne & Naylor (2008MNRAS.386..261M 2008MNRAS.386..261M).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 86 10 Estimated MS and PMS ages of 10 clusters
tables.dat 86 201 Fitted data set for 10 clusters
(tables 2-11 of the paper)
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Cluster Cluster or group name
11- 14 F4.1 Myr AgePMS ? Pre-main sequence age
16- 20 F5.1 Myr AgeMS Main sequence age best fit
22 A1 --- l_AgeMSl Limit flag on AgeMS68
23- 27 F5.1 Myr AgeMSl Lower limit of 68% AgeMS confidence interval
28 A1 --- --- [-]
29- 33 F5.1 Myr AgeMSu ? Upper limit of 68% AgeMS confidence interval
confidence interval
35- 38 F4.2 --- Pr(tau2) Cumulative distribution of the expected
value of τ2 (2)
40- 44 F5.2 mag m-M Cluster distance modulus
46- 49 F4.2 mag E(B-V) B-V colour excess
50 A1 --- n_E(B-V) [ab] Origin of E(B-V) (1)
52- 86 A35 --- Ref Numbering reference system
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Note (1): Origin if of E(B-V):
a = Median from individual extinctions
b = From Brown et al. (1994, Cat. J/A+A/289/101)
Note (2): the τ2 statistics is more adapted to a color-magnitude
diagram where the data points have uncertainties in 2 dimensions;
the method was developped by Naylor and Jeffries (2006MNRAS.373.1251N 2006MNRAS.373.1251N)
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Byte-by-byte Description of file: tables.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Cluster Cluster or group name
12- 17 I6 --- Seq Sequential number
20- 25 F6.3 mag Vmag V magnitude
27- 31 F5.3 mag e_Vmag rms uncertainty on Vmag
34- 39 F6.3 mag B-V B-V colour index
41- 45 F5.3 mag e_B-V rms uncertainty on B-V
48- 53 F6.3 mag U-B ? U-B colour index
55- 59 F5.3 mag e_U-B ? rms uncertainty on U-B
63- 67 F5.3 mag E(B-V) ? B-V colour excess
69- 86 A18 --- SName Simbad name
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 09-Mar-2010