2009ApJ...691..672O


Query : 2009ApJ...691..672O

2009ApJ...691..672O - Astrophys. J., 691, 672-686 (2009/January-3)

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. and MONTESINOS B.

Abstract (from CDS):

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. Individual ages and masses for the YSOs are inferred based on theoretical evolutionary models. The models indicate a spread in stellar ages from 1 Myr to 15 Myr, peaking at 2-6 Myr, and a mass distribution of 0.2-1.2 M with median value around 0.8 M. Strong Hα emission lines (EW[Hα] > 3 Å) have been detected in more than half of the sample (35 stars). The mass accretion rates as derived from the Hα line widths span a broad distribution over four orders of magnitude with median accretion rate of 10–8 M/yr. Our analysis shows that the majority of the IR excess objects detected in Serpens are actively accreting, young T-Tauri stars.

Abstract Copyright:

Journal keyword(s): Hertzsprung-Russell diagram - ISM: individual: Serpens - planetary systems: protoplanetary disks - stars: pre-main sequence

VizieR on-line data: <Available at CDS (J/ApJ/691/672): table2.dat>

Nomenclature: Table 2: [OMP2009] NNN N=78 among (Nos 1-150).

Simbad objects: 82

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Number of rows : 82
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 IC 348 OpC 03 44 34 +32 09.8           ~ 1268 1
2 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1031 1
3 NAME Cha II MoC 12 54 -77.2           ~ 309 0
4 2MASS J18275383-0002335 Y*O 18 27 53.8220872353 -00 02 33.363061455           K2: 10 0
5 2MASS J18280505+0006593 Y*O 18 28 05.0551704399 +00 06 59.077276608           M4: 3 0
6 2MASS J18280848-0001065 Y*O 18 28 08.48 -00 01 06.5           M0: 10 0
7 2MASS J18281102-0001391 Y*O 18 28 11.0180480105 -00 01 39.456562162           M5: 5 0
8 SSTc2d J182813.1+000313 * 18 28 13.1642725959 +00 03 12.759289235           M3: 3 0
9 HBC 665 Em* 18 28 13.5200738002 -00 02 49.355955640   15.1       K5: 19 0
10 2MASS J18281502-0002592 Y*O 18 28 15.0330110308 -00 02 59.113913303           M0: 10 0
11 2MASS J18282143+0010409 Y*O 18 28 21.4453481856 +00 10 41.142892766           M2: 10 0
12 2MASS J18282432+0034543 Y*O 18 28 24.3295133312 +00 34 54.383433949           M0: 5 0
13 IRAS 18258-0013 Y*O 18 28 27.3951283176 -00 11 50.252078372           M5: 5 0
14 [OMP2009] 22 * 18 28 30.0172393394 +00 20 14.751307135           M4: 2 0
15 [OMP2009] 23 * 18 28 37.3624877937 +00 19 27.560542803           M7.5: 2 0
16 2MASS J18284481+0048085 Y*O 18 28 44.8127138351 +00 48 08.509667538           M2: 10 0
17 2MASS J18284499+0045239 Y*O 18 28 45.00 +00 45 23.9       16.6   M1: 11 0
18 [OMP2009] 34 * 18 28 48.2758538568 -00 05 30.004581138           M5.5: 2 0
19 [OMP2009] 35 * 18 28 49.3883456655 -00 06 04.516509185           M5: 2 0
20 2MASS J18285021+0009494 TT? 18 28 50.2158480251 +00 09 49.560287045           K5: 17 0
21 2MASS J18285249+0020257 Y*O 18 28 52.50 +00 20 25.8           M7: 9 1
22 2MASS J18285277+0028463 Y*O 18 28 52.779 +00 28 46.37           K2: 15 1
23 2MASS J18285396+0045528 Y*O 18 28 53.9680843595 +00 45 52.781650414       18.7   M0.5: 11 0
24 SSTc2d J182854.0+002930 Y*O 18 28 54.05 +00 29 30.0           M6: 14 2
25 [DCE2008] 204 cor 18 28 54.91 +00 18 32.7           M5: 16 2
26 2MASS J18285530+0020520 Y*O 18 28 55.3039610719 +00 20 52.214212544           M5.5: 10 0
27 2MASS J18285808+0017243 Y*O 18 28 58.0896494487 +00 17 24.384651405       21.9   G3: 16 1
28 2MASS J18285862+0048593 Y*O 18 28 58.6294183545 +00 48 59.264208431           M2.5: 10 0
29 2MASS J18290025+0016578 Y*O 18 29 00.2543426546 +00 16 57.848837376       17.7   K2: 12 0
30 2MASS J18290088+0029312 Y*O 18 29 00.8921044469 +00 29 31.360084271       17.0   K7: 19 0
31 HBC 668 Em* 18 29 01.2258619468 +00 29 33.113212934   16.8       M0.5: 24 0
32 2MASS J18290174+0029463 Y*O 18 29 01.7476648893 +00 29 46.619094383     19.7     M0: 20 0
33 HBC 671 Em* 18 29 01.8367751476 +00 29 54.753564712   18.4       K0: 25 0
34 2MASS J18290394+0020212 Y*O 18 29 03.9404740943 +00 20 21.260486426       15.6   K5: 12 0
35 2MASS J18290576+0022324 Y*O 18 29 05.7679576358 +00 22 32.407861276           A3: 9 0
36 2MASS J18290615+0019442 Y*O 18 29 06.1572284330 +00 19 44.287886834       18.8   M3: 10 0
37 2MASS J18290776+0054036 Y*O 18 29 07.7685940537 +00 54 03.603621305           M1: 10 0
38 2MASS J18290809-0007372 Y*O 18 29 08.1043793619 -00 07 37.309786110           M4: 6 0
39 2MASS J18290980+0034456 Y*O 18 29 09.8083212924 +00 34 45.738464278           M5: 11 0
40 2MASS J18291149+0020385 Y*O 18 29 11.4971777199 +00 20 38.583998009           M0: 12 0
41 2MASS J18291409+0002588 Y*O 18 29 14.0908781726 +00 02 58.556712306           M3: 3 0
42 SSTc2d J182914.8-000424 * 18 29 14.7806530180 -00 04 24.029883105           M3: 3 0
43 2MASS J18291509+0052122 Y*O 18 29 15.1095916114 +00 52 12.068908234           M5.5: 7 0
44 2MASS J18291514+0039377 Y*O 18 29 15.1518493769 +00 39 37.734116211           M4: 8 0
45 2MASS J18291540-0012520 Y*O 18 29 15.4087737877 -00 12 52.099828649           M0.5: 10 0
46 2MASS J18291558+0039116 Y*O 18 29 15.5866195494 +00 39 11.696250588           K5: 11 0
47 IRAS 18267+0016 Y*O 18 29 16.1808329339 +00 18 21.995909986       21.0   K7: 15 0
48 2MASS J18291969+0018030 Y*O 18 29 19.7000213995 +00 18 02.997697362           M0: 10 0
49 2MASS J18292001+0024497 Y*O 18 29 20.0197288753 +00 24 49.770927869           M2: 4 0
50 2MASS J18292184+0019385 Y*O 18 29 21.84 +00 19 38.5           M1: 10 0
51 2MASS J18292249+0034117 Y*O 18 29 22.5124857365 +00 34 12.242206761           M2: 4 0
52 2MASS J18292253+0034176 Y*O 18 29 22.5339347147 +00 34 17.658682831           A3: 6 0
53 2MASS J18292619+0020515 Y*O 18 29 26.1828459000 +00 20 51.577015631           M4: 3 0
54 2MASS J18292928+0017598 Y*O 18 29 29.2805806835 +00 17 59.998055515           M3: 9 0
55 TYC 5099-24-1 Y*O 18 29 32.5544 -00 13 23.617   12.54 10.94     K5: 6 0
56 2MASS J18293320+0012119 Y*O 18 29 33.2055570260 +00 12 12.069843882           M6: 3 0
57 2MASS J18293382+0053115 Y*O 18 29 33.8251294443 +00 53 11.669676075           M7: 3 0
58 2MASS J18293563+0035035 Y*O 18 29 35.632 +00 35 03.52       18.2   K7: 15 0
59 2MASS J18293620+0042163 Y*O 18 29 36.2144674932 +00 42 16.522979163       18.8   F9: 13 0
60 2MASS J18293672+0047577 Y*O 18 29 36.7250748690 +00 47 57.865934718           M0.5: 10 0
61 2MASS J18294021+0015127 Y*O 18 29 40.2165011093 +00 15 12.964573605           K2: 12 0
62 SSTc2d J182940.7-000703 * 18 29 40.6700104594 -00 07 03.442501622           M4: 2 0
63 2MASS J18294122+0049020 Y*O 18 29 41.23 +00 49 02.0       19.3   K7: 10 0
64 2MASS J18294170+0044268 Y*O 18 29 41.7054802301 +00 44 26.934260548           A2: 8 0
65 2MASS J18294301-0016084 Y*O 18 29 43.0147072140 -00 16 08.514957923           K7: 2 0
66 2MASS J18294410+0033559 Y*O 18 29 44.1101340149 +00 33 56.112852732           M0: 14 0
67 2MASS J18294502+0035264 Y*O 18 29 45.0309443971 +00 35 26.577103095       21.6   M0: 12 0
68 2MASS J18294726+0032229 Y*O 18 29 47.2701210458 +00 32 23.072873875           M0: 12 0
69 2MASS J18294727+0039555 Y*O 18 29 47.2746162115 +00 39 55.613737690           M0: 9 0
70 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 986 2
71 2MASS J18295003+0051014 Y*O 18 29 50.0328632913 +00 51 01.451215834       18.0   M2: 10 0
72 2MASS J18295042+0043435 Y*O 18 29 50.4251659988 +00 43 43.582934191           K6: 9 0
73 2MASS J18295130+0027477 Y*O 18 29 51.3046054206 +00 27 47.901317336           A3: 10 0
74 2MASS J18295323+0033127 Y*O 18 29 53.2378072423 +00 33 12.985481341           M0: 3 0
75 2MASS J18295424+0045074 Y*O 18 29 54.2506172125 +00 45 07.602344141       13.5   A4: 9 0
76 IRAS 18273+0047 Y*O 18 29 55.3359837396 +00 49 39.107868476           A3: 6 0
77 2MASS J18295594+0040150 Y*O 18 29 55.9466980976 +00 40 14.960004885           M4: 10 0
78 2MASS J18295715+0033182 Y*O 18 29 57.1600130932 +00 33 18.325416462           G2.5: 8 0
79 IRAS 18274+0112 Y*O 18 29 57.73680 +01 14 05.6940           M4: 137 2
80 2MASS J18300179+0032161 Y*O 18 30 01.798 +00 32 16.14           K7: 10 0
81 2MASS J18300349+0023445 Y*O 18 30 03.5158681315 +00 23 44.985773514           M0: 10 0
82 2MASS J18300865+0058461 Y*O 18 30 08.65 +00 58 46.2           K5: 8 0

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2021.10.27-05:19:08

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