J/AJ/152/36 Low-mass star-forming cores observed with SHARC-II (Suresh+, 2016)
A catalog of low-mass star-forming cores observed with SHARC-II at 350 µm.
Suresh A., Dunham M.M., Arce H.G., Evans II N.J., Bourke T.L., Merello M.,
Wu J.
<Astron. J., 152, 36 (2016)>
=2016AJ....152...36S 2016AJ....152...36S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Molecular clouds ; Millimetric/submm sources
Keywords: ISM: clouds - stars: formation - stars: low-mass - submillimeter: ISM
Abstract:
We present a catalog of low-mass dense cores observed with the
SHARC-II instrument at 350µm. Our observations have an effective
angular resolution of 10'', approximately 2.5 times higher than
observations at the same wavelength obtained with the Herschel Space
Observatory, albeit with lower sensitivity, especially to extended
emission. The catalog includes 81 maps covering a total of 164
detected sources. For each detected source, we tabulate basic source
properties including position, peak intensity, flux density in fixed
apertures, and radius. We examine the uncertainties in the pointing
model applied to all SHARC-II data and conservatively find that the
model corrections are good to within ∼3'', approximately 1/3 of the
SHARC-II beam. We examine the differences between two array scan modes
and find that the instrument calibration, beam size, and beam shape
are similar between the two modes. We also show that the same flux
densities are measured when sources are observed in the two different
modes, indicating that there are no systematic effects introduced into
our catalog by utilizing two different scan patterns during the course
of taking observations. We find a detection rate of 95% for
protostellar cores but only 45% for starless cores, and demonstrate
the existence of a SHARC-II detection bias against all but the most
massive and compact starless cores. Finally, we discuss the
improvements in protostellar classification enabled by these 350µm
observations.
Description:
We present a catalog of low-mass dense cores observed with the
SHARC-II instrument at 350µm. Our observations have an effective
angular resolution of 10'', approximately 2.5 times higher than
observations at the same wavelength obtained with the Herschel Space
Observatory, albeit with lower sensitivity, especially to extended
emission. The catalog includes 81 maps covering a total of 164
detected sources. Table1 lists the targets of this survey. Table4
lists each of these detected sources. In addition to the detected
sources listed in Table4, Table8 lists an additional 48 cores covered
by our maps but not detected in our SHARC-II observations.
Observations were conducted at the Caltech Submillimeter Observatory
(CSO) in 14 observing runs spread over seven years, ranging from 2003
May through 2010 December. All of the data obtained between 2003 May
and 2005 November were previously published (Wu et al. 2007, Cat.
J/AJ/133/1560); here we present updated images and catalogs using a
newer version of the data reduction software (see Section 3). These
data were obtained using the sweep mode of Submillimeter High Angular
Resolution Camera II (SHARC-II), which moves the telescope following
Lissajous curves in both the x and y dimensions. This mode, which
utilizes scan rates between 5 and 10arcsec/s depending on the exact
size mapped, results in a map with a fully sampled central region of
uniform coverage, beyond which the coverage decreases and thus the
noise increases. The size of this central region depends on the exact
observing parameters, but is typically ∼1'-2' for our observations.
Beginning in December 2006, we began experimenting with using the
box-scan observing mode to map larger areas. This mode, which utilizes
faster scan rates (typically in the range of 20-40arcsec/s), moves the
telescope in a straight line at a 45° angle until it hits the
boundary of a box, changes direction such that the angle of reflection
equals the angle of incidence, and continues until the box is fully
sampled. The exact size of the box depends on the observing
parameters, but is typically ∼6'-10' for our observations. As the
box-scan mode is optimized for mapping both larger areas and regions
with extended emission, all data obtained during and after 2008 July
were obtained exclusively in this mode. Some sources were observed in
both the Lissajous and box-scan observing modes. In those cases, only
the box-scan observations are listed in Table1.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 98 81 Observing information
table4.dat 108 164 Source properties
table7.dat 108 29 Lissajous source properties for sources
observed in both scan modes
table8.dat 69 48 Undetected sources
refs.dat 71 63 References
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See also:
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/ApJS/218/1 : BGPS. XI. SHARC-II 350um observations (Merello+, 2015)
J/AJ/145/94 : Protostars luminosities from 2 Spitzer surveys (Dunham+, 2013)
J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)
J/ApJS/179/249 : Low-luminosity embedded protostar population (Dunham+, 2008)
J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/AJ/133/1560 : Spitzer c2d small clouds and cores (Wu+, 2007)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 17 A17 --- Target Core/cloud target name
19- 31 A13 --- OName Other target name
33 A1 --- Scan [BL] Scan type (B=Box-scan, or L=Lissajous) (1)
35- 36 I2 h RAh Hour of Right Ascension (J2000) (2)
38- 39 I2 min RAm Minute of Right Ascension (J2000) (2)
41- 44 F4.1 s RAs Second of Right Ascension (J2000) (2)
46 A1 --- DE- Sign of the Declination (J2000) (2)
47- 48 I2 deg DEd Degree of Declination (J2000) (2)
50- 51 I2 arcmin DEm Arcminute of Declination (J2000) (2)
53- 56 F4.1 arcsec DEs Arcsecond of Declination (J2000) (2)
58- 60 I3 pc Dist [110/440] Assumed distance to the target
62- 63 I2 --- r_Dist [1/22] Reference to where the distance
measurement was obtained; in refs.dat file
65- 66 I2 --- Ref [1/63] Discovery or other representative
reference; in refs.dat file (3)
68- 90 A23 --- Date Observation date
92- 94 I3 mJy/beam rms [8/536] The 1σ rms noise (4)
96- 98 A3 --- Cloud Large cloud complex or region in which the
target is located (5)
--------------------------------------------------------------------------------
Note (1): Core/cloud mapped using the following mode:
B = Box-scan mode. Beginning in December 2006, we began experimenting with
using the box-scan observing mode to map larger areas. This mode, which
utilizes faster scan rates (typically in the range of 20-40arcsec/s),
moves the telescope in a straight line at a 45° angle until it hits
the boundary of a box, changes direction such that the angle of
reflection equals the angle of incidence, and continues until the box
is fully sampled. The exact size of the box depends on the observing
parameters, but is typically ∼6'-10' for our observations. As the
box-scan mode is optimized for mapping both larger areas and regions
with extended emission, all data obtained during and after 2008 July
were obtained exclusively in this mode. Some sources were observed in
both the Lissajous and box-scan observing modes. In those cases, only
the box-scan observations are listed in the table;
L = Lissajous mode. The 2003 May-2005 November data were obtained using the
sweep mode of Submillimeter High Angular Resolution Camera II
(SHARC-II), which moves the telescope following Lissajous curves in
both the x and y dimensions. This mode, which utilizes scan rates
between 5 and 10arcsec/s depending on the exact size mapped, results in
a map with a fully sampled central region of uniform coverage, beyond
which the coverage decreases and thus the noise increases. The size of
this central region depends on the exact observing parameters, but is
typically ∼1'-2' for our observations.
Note (2): Map center coordinates ordered by increasing right ascension.
Note (3): As there is significant ambiguity in choosing a single representative
reference for each target, we refer the reader to the SIMBAD database for a
comprehensive list of references for each object.
Note (4): The noise is measured as the standard deviation of all off-source
pixels, calculated using the sky procedure in the IDL Astronomy Library.
Two versions of each map are produced, one with and one without extended
emission preserved (see Section 3 for details); the noise is measured in
the maps without extended emission preserved.
Note (5): The code for the cloud or region associated with the target is defined
as follows:
P = Perseus;
T = Taurus;
O = Ophiuchus;
Pi = Pipe;
S/A = Serpens/Aquila;
CA = Corona Australis;
C = Cepheus;
I = Isolated.
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Byte-by-byte Description of file: table[47].dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Source Name of the extracted source
27- 43 A17 --- Target Core/cloud target name (map in which the
source is covered)
45- 46 I2 h RAh Hour of Right Ascension for the peak (J2000)
48- 49 I2 min RAm Minute of Right Ascension for the peak (J2000)
51- 54 F4.1 s RAs Second of Right Ascension for the peak (J2000)
56 A1 --- DE- Sign of the Declination (J2000)
57- 58 I2 deg DEd Degree of Declination for the peak (J2000)
60- 61 I2 arcmin DEm Arcminute of Declination for the peak (J2000)
63- 66 F4.1 arcsec DEs Arcsecond of Declination for the peak (J2000)
68- 71 F4.1 arcsec Rad [3/81]? Deconvolved angular source radius (1)
73- 76 F4.1 Jy/beam Spk [0.1/68.3] Peak intensity (Speak) (2)
78- 82 F5.2 Jy/beam e_Spk [0.03/14.3] Uncertainty in Spk
84- 88 F5.1 Jy S20 [0.2/253.9]? Flux density in a 20'' diameter
aperture
90- 94 F5.2 Jy e_S20 [0.05/65.5]? Uncertainty in S20
96-100 F5.1 Jy S40 [0.1/249.7]? Flux density in a 40'' diameter
aperture
102-106 F5.2 Jy e_S40 [0.03/81.5]? Uncertainty in S40
108 A1 --- S [PS] Source status (P=protostellar core,
or S=starless core) (3)
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Note (1): As determined by Bolocat (see Rosolowsky et al. 2010,
Cat. J/ApJS/188/123, for details).
Note (2): The peak intensities are given in units of Jy/beam (for the SHARC-II
beam, 1Jy/beam=519.7MJy/sr).
Note (3): Determined mostly from a search for an infrared point source in
Spitzer Space Telescope images from the c2d (e.g., Evans et al. 2009,
Cat. J/ApJS/181/321) and Gould Belt (e.g., Dunham et al. 2015,
Cat. J/ApJS/220/11) legacy projects.
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Byte-by-byte Description of file: table8.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 22 A22 --- Source Name of the undetected source (1)
24- 40 A17 --- Target Core/cloud target name
42- 43 I2 h RAh Hour of Right Ascension (J2000)
45- 46 I2 min RAm Minute of Right Ascension (J2000)
48- 51 F4.1 s RAs Second of Right Ascension (J2000)
53 A1 --- DE- Sign of the Declination (J2000)
54- 55 I2 deg DEd Degree of Declination (J2000)
57- 58 I2 arcmin DEm Arcminute of Declination (J2000)
60- 63 F4.1 arcsec DEs Arcsecond of Declination (J2000)
65 A1 --- S [PS] Status (P=protostellar core, or S=starless
core)
67- 69 I3 mJy/beam rms [52/478] The 1σ noise
--------------------------------------------------------------------------------
Note (1): Additional 48 cores covered by our maps but not detected in our
SHARC-II observations. These are cores identified by other observations at
submillimeter and millimeter wavelengths, based on SIMBAD searches of the
total area covered by our maps.
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Byte-by-byte Description of file: refs.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Ref [1/63] Reference identifier
4- 22 A19 --- BibCode Bibliographic Code
24- 51 A28 --- Aut Author's name
53- 71 A19 --- Cat VizieR catalog
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 16-Sep-2016