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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 99 254 Data for rotator sample
table2.dat 55 16 Data for rotators with 1%<FAP<5%
(FAP = false alarm probability)
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Byte-by-byte Description of file: table1.dat table2.dat
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Bytes Format Units Label Explanations
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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 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 1998ApJ...492..540H)
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Note (1): Source: Jones & Walker, 1988AJ.....95.1755J 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.
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History: From electronic AJ version
(End) James Marcout, Patricia Bauer [CDS] 14-Sep-1999