J/ApJS/179/249 Low-luminosity embedded protostar population (Dunham+, 2008)
Identifying the low-luminosity population of embedded protostars in the c2d
observations of clouds and cores.
Dunham M.M., Crapsi A., Evans II N.J., Bourke T.L., Huard T.L., Myers P.C.,
Kauffmann J.
<Astrophys. J. Suppl. Ser., 179, 249-282 (2008)>
=2008ApJS..179..249D 2008ApJS..179..249D (SIMBAD/NED BibCode)
ADC_Keywords: YSOs ; Stars, nearby ; Infrared sources ; Cross identifications
Keywords: stars: formation - stars: low-mass, brown dwarfs
Abstract:
We present the results of a search for all embedded protostars with
internal luminosities ≤1.0L☉ in the full sample of nearby,
low-mass star-forming regions surveyed by the Spitzer Space Telescope
Legacy Project "From Molecular Cores to Planet Forming Disks" (c2d).
We present a set of selection criteria used to identify candidates
from the Spitzer data and examine complementary data to decide whether
each candidate is truly an embedded protostar. Between 75% and 85% of
cores classified as starless prior to being observed by Spitzer remain
starless to our luminosity sensitivity; the remaining 15%-25% harbor
low-luminosity, embedded protostars. We compile complete spectral
energy distributions for all 50 objects and calculate standard
evolutionary signatures (Lbol, Tbol, and Lbol/Lsmm) and argue
that these objects are inconsistent with the simplest picture of star
formation, wherein mass accretes from the core onto the protostar at a
constant rate.
Description:
The c2d project obtained complete 3.6-160um Spitzer maps of five
nearby, large molecular clouds.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 104 49 Candidate low-luminosity embedded objects in cores
table4.dat 104 70 Candidate low-luminosity embedded objects in Per
table5.dat 104 16 *Candidate low-luminosity embedded objects in Cha II
table6.dat 104 42 Candidate low-luminosity embedded objects in Lup
table7.dat 104 22 Candidate low-luminosity embedded objects in Oph
table8.dat 104 19 Candidate low-luminosity embedded objects in Ser
table10.dat 62 218 Candidates divided into groups
table11.dat 75 515 SEDs (Spectral Energy Distributions) of groups 1-3
refs.dat 76 29 References
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Note on table5.dat: For source 127, initial group "5" modified into "6",
according to tables 9 and 10 of the paper.
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See also:
J/ApJ/663/1149 : MIPS and IRAC Serpens YSO population (Harvey+, 2007)
J/AJ/133/1560 : Spitzer c2d small clouds and cores (Wu+, 2007)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJ/676/427 : MIPS and IRAC Chamaeleon II PMS data (Alcala+, 2008)
J/ApJS/177/551 : Spitzer c2d survey of Lupus dark clouds (Merin+, 2008)
Byte-by-byte Description of file: table[345678].dat
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Bytes Format Units Label Explanations
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1- 3 I03 --- [DCE2008] Source number
5- 6 A2 --- Group Group number (G1)
8- 26 A19 --- SSTc2d Spitzer source name (JHHMMSS.ss+DDMMSS.s) (2)
28- 42 A15 --- Region Region designation (3)
44- 46 I3 pc Dist ? Distance to the core region for table 3 (4)
48- 50 I3 pc e_Dist ? Error in Dist
52- 53 I2 h RAh Hour of right ascension (J2000)
55- 56 I2 min RAm Minute of right ascension (J2000)
58- 62 F5.2 s RAs Second of right ascension (J2000)
64 A1 --- DE- Declination sign (J2000)
65- 66 I2 deg DEd Degree of declination (J2000)
68- 69 I2 arcmin DEm Arcminute of declination (J2000)
71- 74 F4.1 arcsec DEs Arcsecond of declination (J2000)
76- 80 F5.3 solLum LIr Integrated luminosity (5)
81 A1 --- f_LIr [e] No 70um data (6)
83- 88 F6.1 arcsec dIRAS Distance to the nearest IRAS source
90- 93 A4 --- --- [IRAS]
95-104 A10 --- IRAS Nearest IRAS source name (IRAS HHMMm-DDMM)
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Note (2): All source names are preceded by the prefix "SSTc2d."
Note (3): Name of the core region from Evans et al. (2007, Final Delivery
of Data from the c2d Legacy Project: IRAC and MIPS (Pasadena: SSC),
http://ssc.spitzer.caltech.edu/legacy/all.html ) in which this source
is located for table 3. Name of the Lupus region (I, III, or IV) in
which this source is located for table 6.
Note (4): These distances have been derived by reddening or association
with regions with known distances (T. Bourke 2008, private
communication). The full list of distances to core regions will be
presented by T. Huard et al. (2008, in preparation).
Note (5): Integrated luminosity using all available detections between 1.25
(2MASS J band) and 70um.
Note (6): A flag "e" denotes that the calculation only extends to 24um due
to no flux information available at 70um.
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Group Group number (G1)
4- 6 I03 --- [DCE2008] Source number
7 A1 --- f_[DCE2008] [c] Flag on source (1)
9- 23 A15 --- Region Core/cloud name
25- 29 F5.3 solLum LIr Integrated luminosity, as in tables 3-8
30 A1 --- f_LIr [e] No 70um data, as in tables 3-8
32- 34 A3 --- MIPS3 Status of 160um observations (4)
36- 62 A27 --- SName Simbad name (5)
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Note (1): Source 132 is the same as Source 017 and thus, has been removed
from table 11.
Note (4): Indicates whether each candidate is associated with a 160um
source. Status as follows:
Y = Yes
N = No
U = Unknown - located off the edge of the 160um map
C/S = Unknown - located in a region that is confused
and/or saturated at 160um
N/A = Not applicable for the dense cores
Note (5): For source 80, IRAS 03267+3218 corrected into IRAS 03267+3128.
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Byte-by-byte Description of file: table11.dat
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Bytes Format Units Label Explanations
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1- 3 I03 --- [DCE2008] Source number
5- 11 F7.2 um lambda Wavelength λ
13- 20 F8.2 mJy Flux Flux density at λ
22- 30 F9.3 mJy e_Flux ? The 1σ uncertainty in Flux
32- 35 A4 arcsec Aper Aperture (1)
37- 42 A6 --- Ref Reference in refs.dat file
44- 75 A32 --- Evol Evolutionary indicator comments
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Note (1): Diameter of the aperture used for photometry at λ>100um,
where the sources are likely to be extended, when specified. A "T"
indicates the photometry is an attempt to derive the total source flux
density rather than the flux density in a fixed aperture; see
individual references for descriptions of the methods used to
derive this quantity.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference number
4- 22 A19 --- BibCode Bibcode
24- 40 A17 --- Aut Author's name
42- 76 A35 --- Com Comment
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Global notes:
Note (G1): Group indicating likelihood of being an embedded protostar.
Group number as follows (see section 5.2 for more details):
1 = Candidates that are confirmed as embedded, low-luminosity protostars
2 = candidates that have a very high likelihood of being embedded,
low-luminosity protostars.
3 = Candidates that have a high likelihood of being embedded,
low-luminosity protostars, although not as high as group 2 candidates.
4 = Candidates that show evidence for being embedded, low-luminosity
protostars but lack confirmation that either level of certainty is
fulfilled. This group is subdivided into 3 groups:
4a = Sources associated with regions of high column density and show
extended nebulosity and/or jets in 4.5um Spitzer images,
4b = Sources only associated with regions of high column density,
4c = Sources only show extended nebulosity and/or jets in 4.5um
Spitzer images.
5 = Candidates that might be embedded, low-luminosity protostars, but
show no sign of being such objects in their limited available data.
6 = Candidates that are most likely not embedded, low-luminosity protostars.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 16-Sep-2009