J/ApJ/691/672 Spectroscopy of YSOs in Serpens molecular cloud (Oliveira+ 2009)
Optical characterization of a new young stellar population in the Serpens
molecular cloud.
Oliveira I., Merin B., Pontoppidan K.M., van Dishoeck E.F., Overzier R.A.,
Hernandez J., Sicilia-Aguilar A., Eiroa C., Montesinos B.
<Astrophys. J., 691, 672-686 (2009)>
=2009ApJ...691..672O 2009ApJ...691..672O
ADC_Keywords: YSOs ; Spectral types ; Extinction ; Cross identifications ;
Molecular clouds
Keywords: Hertzsprung-Russell diagram - ISM: individual (Serpens) - planetary
systems: protoplanetary disks - stars: pre-main sequence
Abstract:
We report on the results of an optical spectroscopic survey designed
to confirm the youth and determine the spectral types among a sample
of young stellar object (YSO) candidates in the Serpens molecular
cloud. We observed 150 infrared (IR) excess objects previously
discovered by the Spitzer Legacy Program "From Molecular Cores to
Planet-Forming Disks" (c2d), bright enough for subsequent
Spitzer/InfraRed Spectrograph (IRS) spectroscopy. We obtained 78
optical spectra of sufficient signal-to-noise for analysis.
Extinctions, effective temperatures, and luminosities are estimated
for this sample, and used to construct Hertzsprung-Russell (H-R)
diagrams for the population. We identified 20 background giants
contaminating the sample, based on their relatively high extinction,
position in the H-R diagram, the lack of Hα emission and
relatively low IR excess. Such strong background contamination (25%)
is consistent with the location of Serpens being close to the Galactic
plane (5° Galactic latitude). The remaining 58 stars (75%) were
all confirmed to be young, mostly K- and M-type stars that are
presumed to belong to the cloud. Our analysis shows that the majority
of the IR excess objects detected in Serpens are actively accreting,
young T-Tauri stars.
Description:
The spectroscopic data were obtained during observing runs at three
telescopes: two runs with the multi-object Wide Field Fibre Optical
Spectrograph (WYFFOS) at the 4.2m William Herschel Telescope (WHT) in
2006 May and 2007 June, and one run with the 3.6m Device Optimized for
the LOw RESolution (DOLORES) at the Telescopio Nazionale Galileo (TNG)
in 2006 June, both telescopes are located at the Observatorio del
Roque de los Muchachos in La Palma, and one run with the Calar Alto
Faint Object Spectrograph (CAFOS) at the 2.2m Calar Alto Telescope in
2008 June.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 55 78 Spectral types for the YSO candidates in Serpens
table3.dat 111 78 Other stellar parameters for the YSO candidates
table4.dat 33 58 Hα equivalent widths and line widths and mass
accretion rates for YSOs in Serpens
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See also:
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJ/684/1240 : Prestellar cores in Perseus, Serpens and Ophiuchus (Enoch+,
2008)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/A+A/463/275 : Chandra obs. of Serpens star-forming region (Giardino+, 2007)
J/ApJ/669/493 : Spitzer/Chandra YSOs in Serpens cloud core (Winston+, 2007)
J/A+A/421/623 : ISOCAM survey of YSOs in Serpens Cloud Core (Kaas+, 2004)
J/A+A/337/403 : Low-mass stars evolutionary models (Baraffe+ 1998)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Running number (<[OMP2009] NNN> in Simbad)
5- 7 I3 --- HMH07 ? Identification from Harvey et al. 2007,
Cat. J/ApJ/663/1149 (<[HMH2007] NNN> in Simbad)
9- 24 A16 --- SSTc2d SSTc2d identification (HHMMSSss+DDMMSSs)
(<SSTc2d JHHMMSS.s+DDMMSS> in Simbad)
26- 30 F5.2 --- alpha α2-24um slope (1)
32- 35 A4 --- SpT MK spectral type
37- 39 F3.1 --- e_SpT Subtype uncertainty
41- 44 F4.1 mag AVobs Extinction found in this work
46- 50 F5.2 mag AVCl Extinction found by "c2d" over 5' region
52- 55 F4.1 mag AV ? Final extinction
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Note (1): Obtained from a linear fit to the logarithm of the fluxes between
the 2MASS K (2um) and the MIPS1 (24um) bands (Harvey et al. 2007, Cat.
J/ApJ/663/1149).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq Running number (<[OMP2009] NNN> in Simbad)
4- 6 A3 --- f_Seq [a,bc ] Flag on Seq (1)
8- 11 I4 K Teff Effective temperature
13- 16 I4 K E_Teff Positive error on Teff
18- 21 I4 K e_Teff Negative error on Teff
23- 28 F6.2 Lsun L* ? Luminosity
30- 35 F6.2 Lsun E_L* ? Positive error on L*
37- 42 F6.2 Lsun e_L* ? Negative error on L*
44- 49 F6.2 Myr AgeB ? Age (2)
51- 56 F6.2 Myr E_AgeB ? Positive error on AgeB
58- 63 F6.2 Myr e_AgeB ? Negative error on AgeB
65- 68 F4.2 Msun MassB ? Mass (2)
70- 73 F4.2 Msun E_MassB ? Positive error on MassB
75- 78 F4.2 Msun e_MassB ? Negative error on MassB
80- 84 F5.2 Myr AgeS ? Age (3)
86- 90 F5.2 Myr E_AgeS ? Positive error on AgeS
92- 96 F5.2 Myr e_AgeS ? Negative error on AgeS
98-101 F4.2 Msun MassS ? Mass (3)
103-106 F4.2 Msun E_MassS ? Positive error on MassS
108-111 F4.2 Msun e_MassS ? Negative error on MassS
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Note (1): Flag as follows:
a = background objects
b = Post-AGB stars, confirmed with Spitzer IRS spectra
c = Objects without 2MASS J, H, and K magnitudes
Note (2): Values derived from the Baraffe et al. models
(1998, Cat. J/A+A/337/403)
Note (3): Values derived from the Siess et al. models (2000A&A...358..593S 2000A&A...358..593S)
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Running number (<[OMP2009] NNN> in Simbad)
5- 9 F5.1 --- EWHa ? Hα (6563Å) equivalent width
(positive value = emission)
11 A1 --- f_EWHa [t] t for classical T Tauri star (CTTS)
based on EWHa
13- 15 I3 km/s Ha10 ? Hα full width at 10% of the peak
intensity
17- 19 I3 km/s e_Ha10 ? Ha10 uncertainty
21 A1 --- f_Ha10 [t] t for CTTS based on Ha10
23- 28 F6.2 [Msun/yr] logdM/dt ? Mass accretion rate
30- 33 F4.2 [Msun/yr] e_logdM/dt ? logM uncertainty
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 22-Feb-2011