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J/AJ/117/2941      Rotation periods of Orion PMS stars       (Stassun+, 1999)

The rotation period distribution of pre-main-sequence stars in and around the Orion nebula. Stassun K.G., Mathieu R.D., Mazeh T., Vrba F.J. <Astron. J. 117, 2941 (1999)> =1999AJ....117.2941S
ADC_Keywords: Stars, pre-main sequence ; Radial velocities ; Equivalent widths Keywords: stars: evolution - stars: pre-main-sequence - stars: rotation - stars: spots Abstract: We report rotation periods for 254 stars in an area 40'x80' centered on the Orion Nebula. We show that these stars are likely members of the young (∼106yr) Orion OBIc/d association. The rotation period distribution we determine, which is sensitive to periods 0.1<P<8days, shows a sharp cutoff for periods P<0.5days, corresponding to breakup velocity for these stars. Above 0.5days the distribution is consistent with a uniform distribution; we do not find evidence for a "gap" of periods at 4-5days. We find signatures of active accretion among stars at all periods; active accretion does not occur preferentially among slow rotators in our sample. We find no correlation between rotation period and near-IR signatures of circumstellar disks. In addition, we show that the distribution of vsini among stars in our sample bears striking resemblance to that of low-mass Pleiades stars. We discuss the implications of our findings for the evolution of stellar angular momentum during the pre-main-sequence phase. We argue that all stars in our sample must still deplete angular momentum by factors of roughly 5-10, if they are to preserve their vsini distribution over approximately the next 100Myr. We consider in detail whether our findings are consistent with disk-regulated stellar rotation. We do not find observational evidence that magnetic disk-locking is the dominant mechanism in angular momentum evolution during the premain-sequence phase. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 99 254 Data for rotator sample table2.dat 99 16 Data for rotators with 1%<FAP<5% (FAP = false alarm probability)
Byte-by-byte Description of file: table1.dat table2.dat
Bytes Format Units Label Explanations
1- 4 I4 --- [SMM99] Star number 6- 9 I4 --- JW ? JW number (1) 10 A1 --- n_JW [k] Hillenbrand (1997, Cat. J/AJ/113/1733) identifies this star as JW466 11- 12 I2 h RAh Right ascension (J2000.0) (2) 14- 15 I2 min RAm Right ascension (J2000.0) 17- 21 F5.2 s RAs Right ascension (J2000.0) 23 A1 --- DE- Declination sign (J2000.0) 24- 25 I2 deg DEd Declination (J2000.0) 27- 28 I2 arcmin DEm Declination (J2000.0) 30- 33 F4.1 arcsec DEs Declination (J2000.0) 35- 38 F4.1 mag Imag I magnitude 40- 44 F5.2 d Per Rotation period 45 A1 --- n_Per [j] j: Detected at limit of period search 46- 49 F4.2 d e_Per ? rms uncertainty on Per (3) 51- 55 F5.2 d PerCH ? Rotation period from Choi & Herbst, 1996AJ....111..283C 57- 60 F4.1 0.1nm EWHa ? Hα equivalent width (4) 61 A1 --- n_EWHa [i] i: Strong Hα emitter 62- 65 F4.2 0.1nm EWLi ? Li equivalent width (5) 67- 69 F3.1 0.1nm FWHMLi ? Li FWHM (5) 71- 74 F4.1 km/s RV ? Radial velocity 76- 77 I2 % Memb ? Membership probability (1) 79- 83 F5.2 solMass Mass ? Mass (Hillenbrand, 1997, Cat. J/AJ/113/1733) 85- 88 F4.2 solRad Rad ? Radius (Hillenbrand, Cat. J/AJ/113/1733) 90- 93 F4.2 --- v/vbr ? Velocity to break-up velocity ratio 95- 99 F5.2 --- D(I-K) ? Near-IR excess emission (Hillenbrand et al. 1998ApJ...492..540H)
Note (1): Source: Jones & Walker, 1988AJ.....95.1755J ID numbers 3000- and 5000- correspond to ID numbers from Hillenbrand, 1997, Cat. J/AJ/113/1733 Note (2): Coordinates referenced to USNO-A1.0 astrometric database. Note (3): Uncertainty computed as in text. A value of zero indicates an uncertainty less than 0.005 days. Note (4): A value of zero indicates no detected Hα emission outside the nebular line. Values indicate emission strength. Note (5): A value of zero indicates no detected Li absorption. Values indicate absorption strength.
History: From electronic AJ version
(End) James Marcout, Patricia Bauer [CDS] 14-Sep-1999
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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