J/ApJ/714/778 YSOs in the Serpens Molecular Cloud (Oliveira+, 2010)
A Spitzer survey of protoplanetary disk dust in the young Serpens cloud: how do dust characteristics evolve with time? Oliveira I., Pontoppidan K.M., Merin B., van Dishoeck E.F., Lahuis F., Geers V.C., Jorgensen J.K., Olofsson J., Augereau J.-C., Brown J.M. <Astrophys. J., 714, 778-798 (2010)> =2010ApJ...714..778O
ADC_Keywords: Molecular clouds ; Spectra, infrared ; YSOs ; Spectral types ; Cross identifications Keywords: circumstellar matter - infrared: stars - planetary systems - protoplanetary disks - stars: pre-main sequence Abstract: We present Spitzer InfraRed Spectrograph (IRS) mid-infrared (5-35um) spectra of a complete flux-limited sample (≥3mJy at 8um) of young stellar object (YSO) candidates selected on the basis of their infrared colors in the Serpens Molecular Cloud. Spectra of 147 sources are presented and classified. Background stars (with slope consistent with a reddened stellar spectrum and silicate features in absorption), galaxies (with redshifted polycyclic aromatic hydrocarbon (PAH) features), and a planetary nebula (with high ionization lines) amount to 22% of contamination in this sample, leaving 115 true YSOs. Sources with rising spectra and ice absorption features, classified as embedded Stage I protostars, amount to 18% of the sample. The remaining 82% (94) of the disk sources are analyzed in terms of spectral energy distribution shapes, PAHs, and silicate features. The presence, strength, and shape of these silicate features are used to infer disk properties for these systems. About 8% of the disks have 30/13um flux ratios consistent with cold disks with inner holes or gaps, and 3% of the disks show PAH emission. Description: Out of the 147 objects in our sample (the same as in Oliveira et al. 2009, Cat. J/ApJ/691/672), 22 were observed between 2004 September and 2006 June, as part of the c2d IRS 2nd Look campaign. The other 125 targets were observed as part of Spitzer Space Telescope's cycle 3 program (GO3 30223, PI: Pontoppidan) in the low resolution module (SL and Long Low (LL), 14.0-38.0um) in 35 acousto-optical spectrometers (AORs), between 2006 October and 2007 April. All objects were observed in IRS staring mode. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 73 147 Observed objects in Serpens table2.dat 44 115 Characteristics of YSOs in Serpens
See also: J/ApJ/692/973 : Protostars in Perseus, Serpens and Ophiuchus (Enoch+, 2009) J/ApJ/691/672 : Spectrocopy of YSOs in Serpens molecular cloud (Oliveira+ 2009) J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007) J/ApJ/669/493 : Spitzer/Chandra YSOs in Serpens cloud core (Winston+, 2007) J/A+A/463/275 : Chandra obs. of Serpens star-forming region (Giardino+, 2007) J/A+A/458/789 : ISOCAM survey of Serpens/G3-G6 (Djupvik+, 2006) J/A+A/421/623 : ISOCAM survey of YSOs in Serpens Cloud Core (Kaas+, 2004) http://irsa.ipac.caltech.edu/data/SPITZER/docs/spitzermission/ observingprograms/legacy/c2d/ : Spitzer c2d data deliveries page Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [OMP2009] Number as in Oliveira et al. (2009, Cat. J/ApJ/691/672) 5- 7 I3 --- [HMH2007] ? Identification number from Harvey et al. (2007, Cat. J/ApJ/663/1149) 9- 24 A16 --- SSTc2d (HHMMSSss+DDMMSSs; J2000; <SSTc2d JHHMMSS.s+DDMMSS> in Simbad) 26- 30 F5.2 --- alpha 2um-24um spectral slope (1) 32- 34 A3 --- Prog [GO3/c2d] Program identification (2) 36- 43 I8 --- AOR AOR number 45- 54 A10 "YYYY/MM/DD" Date Date of observation 56- 60 F5.2 --- F30/F13 ? Flux ratio between 30 and 13um 62- 73 A12 --- Class Classification (BG star, Cold disk, Disk, Emb, Galaxy or PN candidate)
Note (1): dlog(λFλ)/dlog(λ) between the 2MASS K (2um) and the MIPS1 (24um) bands (Harvey et al. 2007, Cat. J/ApJ/663/1149). Note (2): Program as follows: GO3 = the object was observed as part of the Spitzer Space Telescope's cycle 3 program 30223, PI: K. Pontoppidan. c2d = the object was observed as part of the c2d 2nd Look program, PI: N. Evans.
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 3 I3 --- [OMP2009] Number as in Oliveira et al. (2009, Cat. J/ApJ/691/672) 5 A1 --- Emb [Y/ ] Embedded? 7 A1 --- PAH [Y/ ] PAH emission? (3) 9- 12 F4.2 mJy S9.8 ? 9.8um peak flux 14- 17 F4.2 mJy S11.3 ? 11.3um peak flux 19- 22 F4.2 mJy S10 ? 10um peak flux 24- 27 F4.2 mJy S19 ? 19.0um peak flux 29- 32 F4.2 mJy S23.8 ? 23.8um peak flux 34- 37 F4.2 mJy S20 ? 20um peak flux 39 A1 --- Cl [A-E]? Cluster membership (4) 41- 44 A4 --- SpT MK spectral type
Note (3): All disk sources with PAH in emission show the features at 6.2, 7.7, 8.6, 11.2, and 12.8um. Note (4): The brightest YSOs in Serpens appear to be concentrated in clusters, but a more extended young stellar population exists outside these clusters. For the determination of clusters and their boundaries, we follow the method developed by Jorgensen et al. (2008, Cat. J/ApJ/683/822) for Ophiuchus and Perseus. Using volume density and number of YSOs as criteria, the method consists of a nearest neighbor algorithm, and has as input the complete sample of YSOs in Serpens (Harvey et al. 2007, Cat. J/ApJ/663/1149). The associations are divided into loose (volume density of 1M☉/pc3) and tight (volume density of 25M☉/pc3). Furthermore, the associations are divided into clusters (more than 35 members) and groups (less than 35 members). The results of this method in Serpens yield 2 clusters (A and B) and 3 groups (C, D, and E), that can be seen in Figure 12. Individual memberships are marked in this column. See section 4.1 for further details.
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 17-Apr-2012
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