J/ApJ/745/56 Upper Sco members rotational velocities (Dahm+, 2012)
A correlation between circumstellar disks and rotation in the upper Scorpius OB
association.
Dahm S.E., Slesnick C.L., White R.J.
<Astrophys. J., 745, 56 (2012)>
=2012ApJ...745...56D 2012ApJ...745...56D
ADC_Keywords: Radial velocities ; Rotational velocities ; Photometry, infrared ;
Equivalent widths ; Stars, early-type ; Stars, late-type
Keywords: binaries: spectroscopic - stars: pre-main sequence - stars: rotation
Abstract:
We present projected rotational velocities for 20 early-type (B8-A9)
and 74 late-type (F2-M8) members of the ∼5 Myr old Upper Scorpius OB
Association derived from high-dispersion optical spectra obtained with
the High Resolution Echelle Spectrometer on Keck I and the Magellan
Inamori Kyocera Echelle on the Magellan Clay telescope. The
spectroscopic sample is composed of stars and brown dwarfs with
infrared signatures of circumstellar disks, both primordial and
debris, and non-excess sources of comparable spectral type. We merge
projected rotational velocities, accretion diagnostics, and Spitzer
Space Telescope Infrared Array Camera and Multiband Imaging Photometer
for Spitzer 24 µm photometry to examine the relationship between
rotation and circumstellar disks. The rotational velocities are
strongly correlated with spectral type, a proxy for mass, such that
the median vsin i for B8-A9-type stars is: 195±70km/s, F2-K4:
37.8±7.4km/s, K5-K9: 13.8+21.3-8.2km/s, M0-M5: 16.52±5.3km/s,
and M5.5-M8: 17.72±8.1km/s. We find with a probability of ≥0.99
that M-type stars and brown dwarfs having infrared excess suggestive
of circumstellar disks rotate more slowly than their non-excess
counterparts. A similar correlation is present among F2-K9-type stars,
but only at the ∼97% confidence level. Among the early-type (B8-A9)
members, rotational velocities of the debris-disk and non-disk
populations are indistinguishable. Considering the late-type (F2-M8)
stars and brown dwarfs, we find a low fraction of slowly rotating,
non-excess sources relative to younger star-forming regions,
suggesting that most have spun up following disk dissipation. The few
late-type (F2-M5) debris disk sources, which may be representative of
stars that have recently dispersed their inner disks, are evenly
divided between slow and moderate rotators.
Description:
The Upper Scorpius sample was drawn from the Spitzer 4.5-16um
photometric survey of Carpenter et al. (2006, Cat. J/ApJ/651/L49) and
the optical imaging and spectroscopic survey of Slesnick et al. (2006,
Cat.J/AJ/131/3016, 2008, Cat. J/ApJ/688/377).
The HIRES is a grating cross-dispersed spectrograph permanently
mounted on the Nasmyth platform of Keck I. High-dispersion spectra
were obtained for 50 Upper Scorpius members on the nights of 2006 June
16, 2007 May 24-25, 2011 March 19, and 2011 April 24. The B2 and C5
deckers, which have projected slit widths of 2 and 4 pixels, were used
to provide spectral resolutions of ∼66000 and 37500, respectively.
Near complete spectral coverage from ∼4800-9200Å was achieved.
The MIKE is a double echelle spectrograph on the Magellan Clay
telescope at Las Campanas Observatory. High-dispersion red and blue
spectra were obtained for 44 stars and brown dwarfs in Upper Scorpius
using MIKE over four nights from 2008 May 12-15 (resolution of ∼30000
except ∼22000 for the faintest brown dwarf sources).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 155 94 Properties of the Upper Scorpius spectroscopic sample
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See also:
J/MNRAS/431/3222 : UKIDSS GCS Upper Sco members (Lodieu, 2013)
J/A+A/527/A24 : Spectra of low-mass stars in Upper Sco (Lodieu+, 2011)
J/MNRAS/418/1231 : New brown dwarfs in upper Sco (Dawson+, 2011)
J/AJ/139/1338 : UV-selected stars in Tau and Upper Sco (Findeisen+, 2010)
J/ApJ/705/1646 : Debris disks in Upper Sco (Carpenter+, 2009)
J/ApJ/688/377 : Low-mass objects in Upper Scorpius. II. (Slesnick+, 2008)
J/ApJ/651/L49 : Upper Sco OB association IRAC observations (Carpenter+, 2006)
J/AJ/131/3016 : Low-mass objects in Upper Scorpius (Slesnick+, 2006)
J/MNRAS/373/95 : ZYJHK survey of Upper Sco association (Lodieu+, 2006)
J/AJ/121/1040 : PMS members of upper Sco OB association (Preibisch+, 2001)
J/AJ/120/479 : Low-mass stars in the Upper Sco association (Ardila+, 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 22 A22 --- Name Source name
24- 28 A5 --- SpT MK spectral type
30- 35 F6.2 km/s HRV [-50.92/14.6]? Heliocentric radial velocity
37- 40 F4.2 km/s e_HRV [0.1/7.1]? HRV uncertainty
42 A1 --- f_HRV [i] double-lined spectroscopic binary (1)
44- 50 F7.2 mJy [4.5] [1.9/4020]? Spitzer/IRAC 4.5um flux density (2)
52- 59 F8.3 mJy [8.0] [0.8/2269]? Spitzer/IRAC 8um flux density (2)
61 A1 --- l_[24] Limit flag on [24]
63- 69 F7.2 mJy [24] [0.2/1170]? Spitzer/MIPS 24um flux density (2)
71- 72 A2 --- l_vsini [≤ ] Limit flag on vsini
74- 79 F6.2 km/s vsini [4.48/400]? Projected rotational velocity
81- 85 F5.2 km/s e_vsini [0.13/26]? vsini uncertainty
87 A1 --- f_vsini [g] rotational velocity of primary (1)
89- 95 F7.2 0.1nm W(Ha) [-219.51/-0.1]? Hα equivalent width
(negative values imply emission)
97 A1 --- f_W(Ha) [a] a = abs (blank value for W(Ha))
99-104 F6.2 km/s Ha10 [88.46/616.5]? Velocity width of Hα
emission profiles at 10% of peak flux
106-115 A10 --- Disk Disk status (Debris, Non-excess or Primordial)
117-125 A9 --- Epoch UT Date of observation (YYYYMMDD) with
prefix: H=HIRES, M=MIKE
127-153 A27 --- Comm Comments
155 A1 --- K07 [h] h=Binary identified by Kouwenhoven et al.
(2007A&A...474...77K 2007A&A...474...77K)
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Note (1): Flag as follows:
i = Systemic velocity reported for double-line spectroscopic binaries
g = HIP 78207: vsini provided for primary (400km/s) and secondary
component has vsini =38.2km/s.
Note (2): IRAC and MIPS fluxes from Carpenter et al. (2006, Cat. J/ApJ/651/L49)
and Carpenter et al. (2009, Cat. J/ApJ/705/1646), respectively.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 23-Jul-2013