J/AJ/152/198 Periods of 4-10 Myr old T Tauri members of Orion OB1 (Karim+, 2016)
The rotation period distributions of 4-10 Myr T Tauri stars in Orion OB1: new
constraints on pre-main-sequence angular momentum evolution.
Karim M.T., Stassun K.G., Briceno C., Vivas A.K., Raetz S., Mateu C.,
Downes J.J., Calvet N., Hernandez J., Neuhauser R., Mugrauer M.,
Takahashi H., Tachihara K., Chini R., Cruz-Dias G.A., Aarnio A.,
James D.J., Hackstein M.
<Astron. J., 152, 198-198 (2016)>
=2016AJ....152..198K 2016AJ....152..198K (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Stars, pre-main sequence
Keywords: stars: evolution - stars: pre-main sequence - stars: rotation
Abstract:
Most existing studies of the angular momentum evolution of young
stellar populations have focused on the youngest (≲1-3Myr) T Tauri
stars. In contrast, the angular momentum distributions of older T
Tauri stars (∼4-10Myr) have been less studied, even though they hold
key insights to understanding stellar angular momentum evolution at a
time when protoplanetary disks have largely dissipated and when models
therefore predict changes in the rotational evolution that can in
principle be tested. We present a study of photometric variability
among 1974 confirmed T Tauri members of various subregions of the
Orion OB1 association, and with ages spanning 4-10Myr, using optical
time series from three different surveys. For 564 of the stars (∼32%
of the weak-lined T Tauri stars and ∼13% of the classical T Tauri
stars in our sample) we detect statistically significant periodic
variations, which we attribute to the stellar rotation periods, making
this one of the largest samples of T Tauri star rotation periods yet
published. We observe a clear change in the overall rotation period
distributions over the age range 4-10Myr, with the progressively older
subpopulations exhibiting systematically faster rotation. This result
is consistent with angular momentum evolution model predictions of an
important qualitative change in the stellar rotation periods starting
at ∼5Myr, an age range for which very few observational constraints
were previously available.
Description:
The Astronomia Variability Survey of Orion (CVSO) was carried out at
the Llano del Hato National Astronomical Observatory in Venezuela,
with the QUEST CCD mosaic camera (8000*8000pixels) on the 1m (clear
aperture) Schmidt telescope, with a plate scale of 1.02''/pixel and
field of view of 5.4 deg2. This V-, RC-, and IC-band multi-epoch
survey, covering ∼180deg2 of the Orion OB1 association, spans a time
baseline of 12yr, from 1998 December to 2011 February.
The 25 Ori cluster was observed by the 0.6/0.9m Schmidt-type telescope
at Jena Observatory (Germany), the two 5.9'' telescopes at
Observatorio Cerro Armazones (OCA, Chile), and the 1.5m reflector at
the Gunma Astronomical Observatory in Japan, over four observing
campaigns during the years 2010-2013. The Jena Schmidt-type telescope
was equipped with the optical Schmidt Telescope Camera (STK), with an
e2v 42-10 2048*2048 detector, yielding a plate scale of 1.55''/pixel
and a field of view of 53'*53', thus encompassing most of the cluster.
The Jena 50s exposures, all taken through the R filter, were centered
on 25 Ori. A total of 8506 individual exposures were obtained in 108
nights. The Gunma 1.5m reflector observations were carried out by
obtaining 60s integrations in R with the Gunma Low-resolution
Spectrograph and Imager (GLOWS), which has an e2v CCD55-30 1250*1152
pixel detector with a 0.6''/pixel scale, covering a field of view of
12.5'*11.5'. Observations were obtained during four nights in year
2010. The Observatorio Cerro Armazones observations were done in the R
band using the RoBoTT (Robotic Bochum TWin Telescope), which consists
of twin Takahashi 150mm aperture apochromatic astrographs, each
equipped with an Apogee U16M camera with a KAF-16803 4096*4096 pixel
CCD, providing a 2.7°*2.7° field of view with 2.37''/pixel
scale. The 60s exposures were centered on 25 Ori, spanning an area
much larger than the cluster. OCA data were obtained during all YETI
seasons.
During the nights of 2006 January 8-15, we used the 0.9m telescope
with the 8000*8000 pixel MOSAIC imager at the Kitt Peak National
Observatory (KPNO), Arizona, USA, to obtain IC-band time-series
observations of several regions in the Orion OB1 association,
including the 25 Ori cluster in the OB1a subassociation, and fields in
the OB1b subassociation, under NOAO program 2005B-0529.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 116 564 Final periods and False Alarm Probabilities
(FAPs) of all periodic stars
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See also:
II/36 : UBV and uvby-beta obs. of Orion OB1 (Warren+ 1977)
J/MNRAS/444/1793 : 25 Ori group low-mass stars (Downes+, 2014)
J/MNRAS/427/3374 : QUEST RR Lyrae Survey III. (Mateu+, 2012)
J/ApJ/671/1784 : Ori OB1 IRAC/MIPS observations (Hernandez+, 2007)
J/ApJ/661/1119 : Spectroscopy in the 25 Ori group (Briceno+, 2007)
J/AJ/129/907 : New Ori OB1 members (Briceno+, 2005)
J/AJ/117/2941 : Rotation periods of Orion PMS stars (Stassun+, 1999)
J/A+A/289/101 : Orion OB1 association. I. (Brown+, 1994)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- CVSO [4/1975] Running index number from the Centro de
investigaciones de astronomia Variability
Survey of Orion (CVSO)
6- 7 I2 h RAh Hour of Right Ascension (J2000)
9- 10 I2 min RAm Minute of Right Ascension (J2000)
12- 16 F5.2 s RAs Second of Right Ascension (J2000)
18 A1 --- DE- Sign of the Declination (J2000)
19- 20 I2 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 28 F4.1 arcsec DEs Arcsecond of Declination (J2000)
30- 36 A7 --- Loc Source location in the Orion OB1 star-forming
complex (1a, 1b, 25Ori, A cloud, B cloud, or
HR1833) (1)
38- 41 A4 --- Type Source type (CTTS, Ge, or WTTS) (2)
43- 45 I3 --- NI [0/183] Number of I-band observations
47- 51 F5.2 d IPer [0.18/29.57]? Period from I-band observations (3)
53 A1 --- l_IFAP [<] Upper limit flag on IFAP
54- 61 E8.2 --- IFAP ? False Alarm Probability from I-band
observations (3)
63- 67 I5 --- NR [0/13255] Number of R-band observations
69- 73 F5.2 d RPer [0.1/29.35]? Period from R-band observations (3)
75 A1 --- l_RFAP [<] Upper limit flag on RFAP
76- 83 E8.2 --- RFAP ? False Alarm Probability from R-band
observations (3)
85- 87 I3 --- NV [0/174] Number of V-band observations
89- 93 F5.2 d VPer [0.11/29.77]? Period from V-band observations (3)
95 A1 --- l_VFAP [<] Upper limit flag on VFAP
96-103 E8.2 --- VFAP ? False Alarm Probability from V-band
observations (3)
105-109 F5.2 d PMult [0.1/29.62]? Multiband period (3)
111-115 F5.2 d PAdopt [0.11/29.77] Final, adopted period (3)
116 A1 --- f_PAdopt [*] Best period flag (4)
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Note (1): The location of the source is defined as follows:
1a = The ∼10Myr old Orion OB1a subassociation;
1b = The ∼4Myr old Orion OB1b subassociation;
25Ori = The ∼8Myr old 25 Orionis cluster in the Orion OB1a subassociation;
A cloud = Orion A cloud;
B cloud = Orion B cloud;
HR1833 = HR 1833 stellar aggregate.
Note (2): The type of the source is defined as follows:
CTTS = Classical T Tauri Star;
WTTS = Weak-line T Tauri Star;
Ge = Periodic G-type star with Hα emission, which we classify as an
Intermediate-Mass T Tauri Star (IMTTS).
Note (3): We used several methods to determine the most probable period for each
T Tauri Stars (TTSs). We applied the Generalized Lomb-Scargle (GLS)
periodogram (Zechmeister & Kurster 2009A&A...496..577Z 2009A&A...496..577Z) and the Multiband
periodogram (VanderPlas & Ivezic 2015ApJ...812...18V 2015ApJ...812...18V) to calculate the
probable periods, the uncertainty formula described by Kovacs
1981Ap&SS..78..175K 1981Ap&SS..78..175K to calculate the uncertainties in periods, and the
Baluev method (Baluev 2008MNRAS.385.1279B 2008MNRAS.385.1279B) to calculate the False-Alarm
Probability (FAP; we considered a peak to be significant if its FAP is less
than 0.01%). We also used the Wavelet transform method (Bravo et al.
2014A&A...568A..34B 2014A&A...568A..34B) to determine the probable periods for stars with
conflicting periods. All of these methods were combined into a single
pipeline (see Figure 2 in the paper) that provides the most likely period
for each time series while reducing the effect of bias.
Note (4): The best period was adopted on the basis of the wavelet transform
method (Bravo et al. 2014A&A...568A..34B 2014A&A...568A..34B). Further explanation is given in
Section 3.2.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 03-Feb-2017