J/AJ/145/15 Photometry of YSOs in BRC 27 and BRC 34 (Rebull+, 2013)
New young star candidates in BRC 27 and BRC 34.
Rebull L.M., Johnson C.H., Gibbs J.C., Linahan M., Sartore D., Laher R.,
Legassie M., Armstrong J.D., Allen L.E., McGehee P., Padgett D.L.,
Aryal S., Badura K.S., Canakapalli T.S., Carlson S., Clark M., Ezyk N.,
Fagan J., Killingstad N., Koop S., McCanna T., Nishida M.M., Nuthmann T.R.,
O'Bryan A., Pullinger A., Rameswaram A., Ravelomanantsoa T., Sprow H.,
Tilley C.M.
<Astron. J., 145, 15 (2013)>
=2013AJ....145...15R 2013AJ....145...15R
ADC_Keywords: Molecular clouds ; Photometry, infrared ; Photometry, ugriz ; YSOs
Keywords: circumstellar matter - infrared: stars - stars: formation -
stars: pre-main sequence
Abstract:
We used archival Spitzer Space Telescope mid-infrared data to search
for young stellar objects (YSOs) in the immediate vicinity of two
bright-rimmed clouds, BRC 27 (part of CMa R1) and BRC 34 (part of the
IC 1396 complex). These regions both appear to be actively forming
young stars, perhaps triggered by the proximate OB stars. In BRC 27,
we find clear infrared excesses around 22 of the 26 YSOs or YSO
candidates identified in the literature, and identify 16 new YSO
candidates that appear to have IR excesses. In BRC 34, the one
literature-identified YSO has an IR excess, and we suggest 13 new YSO
candidates in this region, including a new Class I object. Considering
the entire ensemble, both BRCs are likely of comparable ages, within
the uncertainties of small number statistics and without spectroscopy
to confirm or refute the YSO candidates. Similarly, no clear
conclusions can yet be drawn about any possible age gradients that may
be present across the BRCs.
Description:
We used the IRAC data for BRC (Bright-Rimmed Cloud) 27 from Spitzer
program 30050, AORKEY 17512192 (an AOR is an Astronomical Observation
Request, the fundamental unit of Spitzer observing. An AORKEY is the
unique eight-digit integer identifier for the AOR, which can be used
to retrieve these data from the Spitzer Archive); for BRC 34, we used
data from Spitzer program 202, AORKEY 6031616. The BRC 27 data were
obtained on 2006 November 22, and were centered on α=07:03:59,
δ=-11:23:09 (J2000); the BRC 34 data were obtained on 2004 July
4 and were centered on α=21:33:32, δ=+58:16:12.8 (J2000).
We used the MIPS data for BRC 27 from Spitzer program 30050, AORKEY
17512448, obtained on 2006 November 4; for BRC 34, we used data from
Spitzer program 202, AORKEY 6031872, obtained on 2004 October 19.
These observations are centered on the same location as the four-band
IRAC data.
We obtained optical observations of our target region from the 2m Las
Cumbres Observatory Global Telescope (LCOGT) Network member telescope,
Faulkes Telescope North (FTN), on Haleakala. The Faulkes telescope has
an ∼10' field of view, easily encompassing our region of interest in
both BRCs. The spatial resolution of the telescope is ∼1.1", most
often seeing-limited; this is well matched to our ∼1.5" resolution
IRAC data. The pixel scale is 0.3"/pixel. The BRC 34 data were
obtained on 2011 October 21 and the BRC 27 data were obtained on 2012
January 2. The filters that we used were Sloan r and i bands.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 177 56 Multiband measurements of known YSOs, literature YSO
candidates, and new Spitzer-identified YSO candidates
in BRC 27 and BRC 34
table3.dat 58 56 Notes on the known YSOs, literature YSO candidates,
and new Spitzer-identified YSO candidates in BRC 27
and BRC 34
notes.dat 322 56 Notes
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See also:
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
J/AJ/143/61 : Hα spectroscopy in IC 1396 HII region (Nakano+, 2012)
J/ApJS/193/25 : The NAN complex. II. MIPS observations (Rebull+, 2011)
J/ApJS/196/4 : New young star candidates in Taurus-Auriga (Rebull+, 2011)
J/MNRAS/415/103 : IPHAS T Tauri candidates in IC 1396 (Barentsen+, 2011)
J/ApJS/186/259 : Taurus Spitzer survey: new candidate members (Rebull+, 2010)
J/ApJ/717/1067 : Triggered star formation in SFO 38 (Choudhury+, 2010)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJ/697/787 : The NAN complex. I. IRAC observations (Guieu+, 2009)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/A+A/506/711 : Canis Major R1 X-ray sources (Gregorio-Hetem+, 2009)
J/MNRAS/396/964 : T Tauri in and around bright-rimmed clouds (Chauhan+, 2009)
J/ApJ/674/336 : Spitzer observations of NGC 1333 (Gutermuth+, 2008)
J/AJ/135/2323 : Hα stars and HH objects near BRCs (Ikeda+, 2008)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/ApJ/660/1532 : Spitzer/IRAC-MIPS survey of NGC 2244 (Balog+, 2007)
J/ApJ/654/316 : X-ray sources in IC 1396N (Getman+, 2007)
J/PASJ/58/L29 : Low-mass stars JHK photometry in BRC 14 (Matsuyanagi+, 2006)
J/AJ/123/2597 : Hα stars and HH objects near BRCs (Ogura+, 2002)
J/AJ/119/3026 : Circumstellar disk candidates in Orion (Rebull+, 2000)
J/MNRAS/310/210 : Stellar composition of CMa R1 (Shevchenko+, 1999)
J/A+A/309/581 : CO observations of clouds in IC 1396 region (Weikard +, 1996)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/56] Running sequence number
4- 6 A3 --- --- [BRC]
8- 9 I2 --- BRC Bright-Rimmed Cloud number (27 or 34) (G1)
11- 25 A15 --- Name Name of the Young Stellar Object (YSO)
<[RJG2013] JHHMMSS.s+DDMMSS> in Simbad
27- 52 A26 --- OName Other(s) name(s) of the YSO
54 A1 --- l_rmag [>] Lower limit flag on rmag
55- 59 F5.2 mag rmag Sloan r band magnitude (AB system)
61- 64 F4.2 mag e_rmag ? Error in rmag
66 A1 --- l_imag [>] Lower limit flag on imag
67- 71 F5.2 mag imag Sloan i band magnitude (AB system)
73- 76 F4.2 mag e_imag ? Error in imag
78 A1 --- l_Jmag [>] Lower limit flag on Jmag
79- 83 F5.2 mag Jmag ? 2MASS J band magnitude (VEGA system)
85- 88 F4.2 mag e_Jmag ? Error in Jmag
90 A1 --- l_Hmag [>] Lower limit flag on Hmag
91- 95 F5.2 mag Hmag 2MASS H band magnitude (VEGA system)
97-100 F4.2 mag e_Hmag ? Error in Hmag
102-106 F5.2 mag Kmag 2MASS Ks band magnitude (VEGA system)
108-111 F4.2 mag e_Kmag Error in Kmag
113-117 F5.2 mag [3.6] Spitzer/IRAC 3.6µm band VEGA magnitude
119-122 F4.2 mag e_[3.6] Error in [3.6]
124-128 F5.2 mag [4.5] Spitzer/IRAC 4.5µm band VEGA magnitude
130-133 F4.2 mag e_[4.5] Error in [4.5]
135-139 F5.2 mag [5.8] Spitzer/IRAC 5.8µm band VEGA magnitude
141-144 F4.2 mag e_[5.8] Error in [5.8]
146-150 F5.2 mag [8.0] Spitzer/IRAC 8.0µm band VEGA magnitude
152-155 F4.2 mag e_[8.0] Error in [8.0]
157 A1 --- l_[24] [>] Lower limit flag on [24]
158-161 F4.2 mag [24] ? Spitzer/MIPS 24µm band VEGA magnitude
163-166 F4.2 mag e_[24] ? Error in [24]
168-172 F5.2 mag [70] ? Spitzer/MIPS 70µm band VEGA magnitude
174-177 F4.2 mag e_[70] ? Error in [70]
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/56] Running sequence number
4- 6 A3 --- --- [BRC]
8- 9 I2 --- BRC Bright-Rimmed Cloud number (27 or 34) (G1)
11- 25 A15 --- Name Name of the Young Stellar Object (YSO)
<[RJG2013] JHHMMSS.s+DDMMSS> in Simbad
27- 40 A14 --- YSO YSO status (1)
42- 47 A6 --- IRx IR excess status (2)
49- 53 F5.2 --- alpha Slope α of the SED between 2 and 24µm (3)
55- 58 A4 --- Cl SED class (I, II, III, or Flat) (4)
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Note (1): YSO status can be decoded as belows:
Lit. YSO cand. = literature YSO candidate;
YSO = literature likely YSO;
New YSO can. = new YSO candidate identified here.
Note (2): IR excess status can be decoded as:
IRx = IR excess detected here;
IRx: = uncertain IR excess identified here;
no IRx = no IR excess detected here.
Note (3): Obtained as described in Section 5.3.2
(α=dlogλFλ/dlogλ).
Note (4): Obtained by binning up the SED slope (α) values as described in
Section 5.3.2 into the classes defined in Section 2.1. The nomenclature we
use here is consistent with (if not actually identical to) the definitions
presented in Evans et al. (2009, cat. J/ApJS/181/321). See Section 2.1 for
more details. Star formation stage as follows:
I = Is likely to last ∼0.5Myr (Evans et al., 2009, cat. J/ApJS/181/321).
This phase is again defined with respect to the shape of the SED-the slope
of the SED between ∼2 and ∼20µm, α, is ≥0.3. In this phase, the
energy emitted is still dominated by that from the envelope, but it is
possible to still detect some evidence of a "photosphere" of the YSO at
the shortest bands (see, e.g., Fig. 11 in Bachiller, 1996ARA&A..34..111B 1996ARA&A..34..111B).
Flat = This stage arises from the group of objects whose SED is in transition
from an SED with a positive slope (where the peak of the energy
distribution is due to the circumstellar material) to a negative slope
(where the peak of the energy distribution is due to the YSO
photosphere). For these objects, -0.3≤α<0.3.
II = This phase may last ∼2Myr (Evans et al., 2009, cat. J/ApJS/181/321), and
physically corresponds to a phase in which there is no more circumstellar
envelope, but an optically thick circumstellar disk remains. The SED
indicates that most of the energy come from the YSO photosphere, though
there is still a substantial contribution from the circumstellar accretion
disk: -1.6≤α< -0.3.
III = Class III objects have little or no excess emission in the infrared due
to a circumstellar disk; for these objects, α< -1.6. These objects
may have tenuous dust disks but substantial gas disks from which they are
still accreting; they may have no disk at all, but their youth is
suggested by e.g., fast rotation or bright X-ray emission. Class III
objects cannot be completely identified using only the IR; since so many
of them have little or no disk, other wavelengths must be employed.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/56] Running sequence number
4-322 A319 --- Note Notes on individual objects as described in the text
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Global notes
Note (G1): BRC 27 is part of the Canis Major (CMa) R1 molecular cloud, and
BRC 34 is one of several BRCs located along the rim of the IC 1396 HII complex.
History:
From electronic version of the journal
(End) Sylvain Guehenneux [CDS] 04-Mar-2014