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J/ApJ/691/672   Spectrocopy 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
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:
FileName Lrecl Records Explanations
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
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
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
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).
Byte-by-byte Description of file: table3.dat
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
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)
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
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
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 22-Feb-2011
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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