J/AJ/155/241 Chandra X-ray detection of YSOs in Serpens South (Winston+, 2018)
Chandra detection of an evolved population of young stars in Serpens South.
Winston E., Wolk S.J., Gutermuth R., Bourke T.L.
<Astron. J., 155, 241-241 (2018)>
=2018AJ....155..241W 2018AJ....155..241W (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; YSOs ; Stars, pre-main sequence ;
X-ray sources ; Photometry, infrared
Keywords: circumstellar matter - infrared: stars - stars: pre-main sequence -
stars: protostars - X-rays: stars
Abstract:
We present a Chandra study of the deeply embedded Serpens South
star-forming region, examining cluster structure and disk properties
at the earliest stages. In total, 152 X-ray sources are detected. Combined
with Spitzer and 2MASS photometry, 66 X-ray sources are reliably matched
to an IR counterpart. We identify 21 class I, 6 flat spectrum, 16 class II,
and 18 class III young stars; 5 were unclassified. Eighteen sources were
variable in X-rays, 8 exhibiting flare-like emission and one source being
periodic. The cluster's X-ray luminosity distance was estimated: the best
match was to the nearer distance of 260 pc for the front of the Aquila
Rift complex. The ratio of NH to AK is found to be ∼0.68x1022,
similar to that measured in other young low-mass regions, but lower than
that measured in the interstellar medium and high-mass clusters
(~(1.6-2)x1022). We find that the spatial distribution closely follows
that of the dense filament from which the stars have formed, with the
class II population still strongly associated with the filament. There
are four subclusters in the field, with three forming knots in the
filament, and a fourth to the west, which may not be associated but may be
contributing to the distributed class III population. A high percentage of
diskless class IIIs (upper limit 30% of classified X-ray sources) in
such a young cluster could indicate that processing of disks is influenced
by the cluster environment and is not solely dependent on timescale.
Description:
The Serpens South cluster was observed by Chandra with the ACIS instrument
on 2010 June 7, in a single epoch with an exposure time of 97.49 ks/pix
as part of OBSID 11013. The ACIS-I field was centered on the J2000
coordinates 18h30m03s, -02°01'58", with a field of view of 17'x17'.
The observation was taken with ACIS-I in FAINT mode, and TE exposure mode
with no grating, and included two of the ACIS-S chips adjacent to the
ACIS-I array.
Serpens South was observed with Spitzer (Werner et al. 2004ApJS..153....1S 2004ApJS..153....1S)
as part of the 5.1 deg2 Serpens-Aquila Rift observation in the Gould Belt
Legacy Survey, PID 30574, on 2006 October 27. IRAC imaging (Fazio et al.
2004ApJS..154...10F 2004ApJS..154...10F) at 3.6, 4.5, 5.8, 8.0 µm was obtained in High
Dynamic Range mode, which obtained integrations of 0.4 and 10.4 s for four
dithered images at each mosaic position. MIPS mosaics (Rieke et al.
2004ApJS..154...25R 2004ApJS..154...25R) (24, 70, 160 µm) were taken at medium scan rate
with full-width scan stepping. Due to the high background and low angular
resolution of the 70 and 160 µm bands, point-source extraction was
applied only to the 24 µm mosaic. The mid-IR photometry was supplemented
by J-, H-, and K-band photometry from the Two Micron All Sky Survey (2MASS)
point-source catalog (Skrutskie et al. 2006, Cat. VII/233).
Objects:
------------------------------------------------------------------------
RA (ICRS) DE Designation(s)
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18 30 03.00 -02 01 58.2 Serpens South = NAME Serpens South Cluster
------------------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 134 152 Chandra X-ray detections
table3.dat 109 66 Infrared photometry of X-ray detections
in Serpens South
table4.dat 130 299 IR properties of identified YSOs in Serpens
South IR-field
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See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/463/275 : Chandra obs. of Serpens star-forming region (Giardino+, 2007)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/149/103 : Spectroscopy of candidate YSOs in Serpens (Erickson+, 2015)
J/ApJ/805/9 : Gould's Belt VLA Survey. II. Serpens region
(Ortiz-Leon+, 2015)
J/A+A/463/275 : Chandra obs. of Serpens star-forming region (Giardino+, 2007)
J/A+A/615/A9 : Distribution of Serpens South protostars (Plunkett+, 2018)
J/AJ/155/99 : IR variability among YSOs in the Serpens South cluster
(Wolk+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/152] Chandra index number
5- 6 A2 --- f_ID [IR] Infrared source counterpart flag (1)
8- 9 I2 h RAh Hour of Right Ascension (J2000)
11- 12 I2 min RAm Minute of Right Ascension (J2000)
14- 20 F7.4 s RAs Second of Right Ascension (J2000)
22 A1 --- DE- Sign of the Declination (J2000)
23 I1 deg DEd Degree of Declination (J2000)
25- 26 I2 arcmin DEm Arcminute of Declination (J2000)
28- 34 F7.4 arcsec DEs Arcsecond of Declination (J2000)
36- 40 F5.2 --- Signi [0.23/32.27]? Source significance
42- 46 F5.2 deg Off [0.05/18.18] Off axis angle
48- 54 F7.2 ct NCts [-22.57/1047.91] Net counts
56- 60 F5.2 ct e_NCts [1.73/32.4] Uncertainty in NCts
62- 66 F5.2 10+22/cm2 NH [0.13/42.28]? H I column density
68- 71 F4.2 10+22/cm2 e_NH [0.03/9.39]? Lower uncertainty in NH
73- 76 F4.2 10+22/cm2 E_NH [0.03/9.39]? Upper uncertainty in NH
78- 82 F5.2 keV kT [0.24/64]? Plasma temperature
84- 88 F5.2 keV e_kT [0.03/43.64]? Lower uncertainty in kT
90- 95 F6.2 keV E_kT [0.03/175.5]? Upper uncertainty in kT
97-104 E8.2 mW/m2 AbsFX [1.83e-41/3.25e-13]? Absorbed X-ray flux (2)
106-113 E8.2 mW/m2 e_AbsFX [1.48e-15/3.09e-13]? Uncertainty in AbsFX (2)
115-122 E8.2 mW/m2 FX [1.54e-29/7.21e-06]? Corrected, unabsorbed
X-ray flux (2)
124-131 E8.2 mW/m2 e_FX [1.11e-15/3.08e-13]? Uncertainty in FX (2)
133-134 A2 --- Var Variable flag (3)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
IR = X-ray source has IR counterpart.
Note (2): In units of erg/s/cm2.
Note (3): Variable flag as follows:
V = Source is X-ray variable;
wV = Source is possibly/weakly X-ray variable.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/152] Chandra index number
5- 9 F5.2 mag Jmag [8.93/16.43]? 2MASS J band magnitude
11- 14 F4.2 mag e_Jmag [0.02/0.14]? Uncertainty in Jmag
16- 20 F5.2 mag Hmag [8.66/15.79]? 2MASS H band magnitude
22- 25 F4.2 mag e_Hmag [0.02/0.18]? Uncertainty in Hmag
27- 31 F5.2 mag Ksmag [8.56/15.05]? 2MASS Ks band magnitude
33- 36 F4.2 mag e_Ksmag [0.02/0.17]? Uncertainty in Ksmag
38- 42 F5.2 mag 3.6mag [6.19/16.21]? Spitzer/IRAC 3.6 micron band
magnitude
44- 47 F4.2 mag e_3.6mag [0/0.27]? Uncertainty in 3.6mag
49- 53 F5.2 mag 4.5mag [5/16.42]? Spitzer/IRAC 4.5 micron band
magnitude
55- 58 F4.2 mag e_4.5mag [0/0.19]? Uncertainty in 4.5mag
60- 64 F5.2 mag 5.8mag [4.05/15.15]? Spitzer/IRAC 5.8 micron band
magnitude
66- 69 F4.2 mag e_5.8mag [0/0.36]? Uncertainty in 5.8mag
71- 75 F5.2 mag 8.0mag [3.39/15.95]? Spitzer/IRAC 8.0 micron band
magnitude
77- 80 F4.2 mag e_8.0mag [0/1.91]? Uncertainty in 8.0mag
82- 85 F4.2 mag 24mag [0.58/8.48]? Spitzer/MIPS 24 micron band
magnitude
87- 90 F4.2 mag e_24mag [0/0.17]? Uncertainty in 24mag
92-100 F9.7 mag AK [0.0189474/8.34302]? K band extinction
102-104 A3 --- SClass SED classification; see Section 3.1 (1)
106-109 I4 --- CClass [-100/99]? Color classification; see Section 3.1
(G1)
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Note (1): SED classification as follows:
FS = Flat spectrum object;
I = Protostar with an infalling envelope;
II = Pre-main sequence star with an optically thick disk;
III = Pre-main-sequence star and unrelated field star;
UNK = Unclassified.
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Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/299] Spitzer/IRAC index number
5- 6 I2 h RAh Hour of Right Ascension (J2000)
8- 9 I2 min RAm Minute of Right Ascension (J2000)
11- 17 F7.4 s RAs Second of Right Ascension (J2000)
19 A1 --- DE- Sign of the Declination (J2000)
20 I1 deg DEd Degree of Declination (J2000)
22- 23 I2 arcmin DEm Arcminute of Declination (J2000)
25- 31 F7.4 arcsec DEs Arcsecond of Declination (J2000)
33- 37 F5.2 mag Jmag [10.43/17.21]? 2MASS J band magnitude
39- 42 F4.2 mag e_Jmag [0.02/0.27]? Uncertainty in Jmag
44- 48 F5.2 mag Hmag [7.09/16.44]? 2MASS H band magnitude
50- 53 F4.2 mag e_Hmag [0.02/0.26]? Uncertainty in Hmag
55- 59 F5.2 mag Ksmag [5.42/15.11]? 2MASS Ks band magnitude
61- 64 F4.2 mag e_Ksmag [0.02/0.16]? Uncertainty in Ksmag
66- 70 F5.2 mag 3.6mag [5.04/16.95]? Spitzer/IRAC 3.6 micron band
magnitude
72- 75 F4.2 mag e_3.6mag [0/0.16]? Uncertainty in 3.6mag
77- 81 F5.2 mag 4.5mag [4.66/15.01]? Spitzer/IRAC 4.5 micron band
magnitude
83- 86 F4.2 mag e_4.5mag [0/0.09]? Uncertainty in 4.5mag
88- 92 F5.2 mag 5.8mag [3.86/13.98]? Spitzer/IRAC 5.8 micron band
magnitude
94- 97 F4.2 mag e_5.8mag [0/0.43]? Uncertainty in 5.8mag
99-103 F5.2 mag 8.0mag [3.05/13.54]? Spitzer/IRAC 8.0 micron band
magnitude
105-108 F4.2 mag e_8.0mag [0/0.78]? Uncertainty in 8.0mag
110-113 F4.2 mag 24mag [0.58/9.83]? Spitzer/MIPS 24 micron band
magnitude
115-118 F4.2 mag e_24mag [0/0.53]? Uncertainty in 24mag
120-128 F9.7 mag AK [0.0280822/8.34302]? K band extinction
130 I1 --- CClass [0/3]? Color classification; see Section 3.1
(G1)
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Global notes:
Note (G1): Color classification as follows:
0/1 = (Deeply) embedded protostar;
2 = Disk-bearing pre-main-sequence object;
3 = Object with weak/anaemic disk;
9 = Shock emission dominated source;
99 = Field star;
-100 = Unclassified.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 18-Dec-2018