J/A+A/597/A63 Slow-rotator sequence radii (Lanzafame+, 2017)
Evidence of radius inflation in stars approaching the slow-rotator sequence.
Lanzafame A.C., Spada F., Distefano E.
<Astron. Astrophys. 597, A63 (2017)>
=2017A&A...597A..63L 2017A&A...597A..63L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, diameters
Keywords: stars: rotation - open clusters and associations: general -
open clusters and associations: The Pleiades -
stars: fundamental parameters
Abstract:
Average stellar radii in open clusters can be estimated from rotation
periods and projected rotational velocities under the assumption of
random orientation of the spin axis. Such estimates are independent of
distance, interstellar absorption, and models, but their validity can
be limited by missing data (truncation) or data that only represent
upper/lower limits (censoring).
We present a new statistical analysis method to estimate average
stellar radii in the presence of censoring and truncation.
We use theoretical distribution functions of the projected stellar
radius Rsini to define a likelihood function in the presence of
censoring and truncation. Average stellar radii in magnitude bins are
then obtained by a maximum likelihood parametric estimation procedure.
This method is capable of recovering the average stellar radius within
a few percent with as few as ∼10 measurements. Here it is applied for
the first time to the dataset available for the Pleiades. We find an
agreement better than ∼10 percent between the observed R vs MK
relationship and current standard stellar models for
1.2≥M/M☉≥0.85 with no evident bias. Evidence of a systematic
deviation at 2sigma level are found for stars with 0.8≥M/M☉=0.6
approaching the slow-rotator sequence. Fast-rotators (P<2d) agree
with standard models within 15 percent with no systematic deviations
in the whole 1.2≥M/M☉≥0.5 range.
The evidence found of a possible radius inflation just below the lower
mass limit of the slow-rotator sequence indicates a possible
connection with the transition from the fast to the slow-rotator
sequence.
Description:
File table1.dat contains the data used in this work with the
rotational sequence classification based on the P vs (B-V) diagram
adapted from Lanzafame and Spada (2015A&A...584A..30L 2015A&A...584A..30L). Mass and
radius are derived from MK according to the Baraffe et al.
(2015A&A...577A..42B 2015A&A...577A..42B) models. Periods are truncated to the 6th decimal
figure. Upper vsini limits are flagged with l_vsini=1, lower limits
with l_vsini=2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 82 217 Data used with the classification in rotational
sequences
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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- 15 A15 --- Name HATNet Designation (HAT-NNN-NNNNNNN) (1)
17- 26 F10.6 deg RAdeg Right ascension J2000 (2)
28- 37 F10.6 deg DEdeg Declination J2000 (2)
39- 43 F5.2 mag B-V ?=-9.99 B-V colour index (2)
45- 49 F5.3 mag KMAG Absolute magnitude in K filter (3)
51- 56 F6.3 Msun Mass ?=-9.999 Stellar mass from MK and
Baraffe et al. (2015A&A...577A..42B 2015A&A...577A..42B) models
58- 63 F6.3 Rsun Radius ?=-9.999 Stellar radius from MK and
Baraffe et al. (2015A&A...577A..42B 2015A&A...577A..42B) models
65- 72 F8.6 d Prot Rotation period, truncated to the 6th decimal
figure (1)
74 I1 --- l_vsini [0/2] Upper or lower-limit flag on vsini (1)(4)
76- 80 F5.1 km/s vsini Projected equatorial rotation velocity (1)
82 A1 --- seq Rotational sequence
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Note (1): from Hartman et al., 2010, Cat. J/MNRAS/408/475.
Note (2): from Stauffer et al., 2007, Cat. J/ApJS/172/663.
Note (3): Obtained from the apparent K magnitude from Stauffer et al. (2007,
Cat. J/ApJS/172/663), the adopted distance to the Pleiades of 136.2pc
(Melis et al., 2014Sci...345.1029M 2014Sci...345.1029M) and an extinction of AK=0.01mag
(Stauffer et al., 2007, Cat. J/ApJS/172/663).
Note (4): Upper or lower-limit flag as follows:
1 = upper vsini limit
2 = lower vsini limit
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Acknowledgements:
Alessandro Lanzafame, a.lanzafame(at)unict.it
(End) Alessandro Lanzafame [UniCt], Patricia Vannier [CDS] 31-Oct-2016