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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 (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). Mass and radius are derived from MK according to the Baraffe et al. (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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 82 217 Data used with the classification in rotational sequences
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
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) models 58- 63 F6.3 Rsun Radius ?=-9.999 Stellar radius from MK and Baraffe et al. (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
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) 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
Acknowledgements: Alessandro Lanzafame, a.lanzafame(at)unict.it
(End) Alessandro Lanzafame [UniCt], Patricia Vannier [CDS] 31-Oct-2016
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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