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J/ApJS/123/233 Catalog of Optically selected cores (Lee+, 1999)
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A catalog of optically selected cores.
Lee C.W., Myers P.C.
<Astrophys. J. Suppl. Ser. 123, 233 (1999)>
=1999ApJS..123..233L
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ADC_Keywords: Photographic catalog ; Interstellar medium ;
Stars, pre-main sequence
Keywords: catalogs - ISM: clouds - stars: pre-main-sequence
Abstract:
We present a new catalog of 406 dense cores optically selected by
using the STScI Digitized Sky Survey (DSS). In this catalog 306 cores
have neither an embedded young stellar object (EYSO) nor a
pre-main-sequence (PMS) star, 94 cores have EYSOs (one core has both
an EYSO and a PMS star), and six cores have PMS stars only. Our sample
of dense cores in the catalog is fairly complete within a category of
northern Lynds class 5 and 6 clouds and southern Hartley et al. class
A clouds, providing a database useful for the systematic study of
dense cores. Most of the cores listed in the catalog have diameters
between 0.05 and 0.36 pc with a mean of ~0.24pc. The sizes (~0.33pc in
the mean) of cores with EYSOs are found to be usually larger than the
sizes (~0.22pc in the mean) of starless cores. The typical mean gas
density of the cores is ~7x10^3^cm^-3^. Most of the cores are more
likely elongated than spherical (mean aspect ratio: ~2.4). The ratio
of the number of cores with EYSOs to the number of starless cores for
our sample is about 0.3, suggesting that the typical lifetime of
starless cores is 0.3-1.6Myr, about 3 times longer than the duration
of the class 0 and class I phases. This lifetime is shorter than
expected from models of ambipolar diffusion, by factors of 2-44.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 44 250 Searched reference regions
table2.dat 78 406 Optically Selected Cores
table3.dat 84 133 IRAS Point Sources and PMS Stars Associated
with Optically Selected Cores
refs.dat 155 32 References to table2
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Region Region designation
14 A1 --- n_Region [*] for region of larger size (1)
16- 17 I2 h RAh Right ascension (B1950)
19- 20 I2 min RAm Right ascension (B1950)
22- 25 F4.1 s RAs Right ascension (B1950)
27 A1 --- DE- Declination sign (B1950)
28- 29 I2 deg DEd Declination (B1950)
31- 32 I2 arcmin DEm Declination (B1950)
34- 35 I2 arcsec DEs Declination (B1950)
37- 41 A5 --- Ref Reference (2)
43- 44 I2 --- Ncore Number of cores selected in each reference region
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Note (1): Searched size of all regions is 30'x30' except for the five
regions marked with an asterisk, whose searched area is 60'x60'
Note (2): References:
Lynds: Lynds, 1962, Cat. <VII/7>
BM: Benson & Myers, 1989ApJS...71...89B
Le: Lemme et al., 1996A&A...312..585L
ON: Onishi et al., 1996ApJ...465..815O
CO: Codella et al., 1997A&A...324..203C
HMSTG: Hartley et al., 1986, Cat. <VII/191>
VMP: Vilas-Boas et al., 1994ApJ...433...96V
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [LM99] Sequential number (1)
5- 22 A18 --- Source Source name
24- 25 I2 h RAh Right ascension (B1950)
27- 28 I2 min RAm Right ascension (B1950)
30- 33 F4.1 s RAs Right ascension (B1950)
35 A1 --- DE- Declination sign (B1950)
36- 37 I2 deg DEd Declination (B1950)
39- 40 I2 arcmin DEm Declination (B1950)
42- 43 I2 arcsec DEs Declination (B1950)
45- 48 F4.1 arcmin Smaj ? Size of major axis of FWHM of selected cores
50- 53 F4.1 arcmin Smin ? Size of minor axis of FWHM of selected cores
55- 58 F4.1 arcmin Diam Equivalent diameter (2)
60- 62 I3 deg PA [-90/90]? Position angle of the core
(- clockwise and + counterclockwise with
respect to equatorial north)
64- 67 A4 --- EYSO [NYPM/* ] Core structure (3)
69 I1 --- DC [1,4] Darkness contrast (4)
71 A1 --- Class Lynds opacity class and Hartley A class
73- 75 I3 pc Dist ? Distance to the cores
77- 78 I2 --- r_Dist ? Reference for core distances in refs.dat file
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Note (1): These 406 sources are positions showing local intensity minima
in the STScI Digitized Sky Survey (DSS).
Note (2): Geometric mean (ab)^0.5^ for the cores whose a and b are
measured, or the equivalent diameter 2x(A/{pi})^0.5^ (where A is the
area within the FWHM contour of the core) for the cores in which a and
b are not measured owing to its irregularity.
Note (3): the structure is described as:
N: starless cores
Y: cores with embedded YSOs
PM: cores with pre-main-sequence (PMS) stars
PM*: PMSs that are determined by optical spectroscopy
(Herbig & Bell, 1988, cat. <V/73>).
Note (4): Darkness contrast of the opaque core to the background, where
1 corresponds to the least dark and 4 to the most dark.
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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 --- RefNo Reference number
4- 22 A19 --- BibCode BibCode
24- 41 A18 --- Aut Authors' names
43-160 A118 --- Object Objects considered
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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- 16 A16 --- Source Source name
18- 27 A10 --- IRAS IRAS or PMS Name
28 A1 --- --- [(]
29 I1 --- n_IRAS [1,4]? Note on IRAS (1)
32- 33 I2 h RAh Right ascension (B1950)
35- 36 I2 min RAm Right ascension (B1950)
38- 41 F4.1 s RAs Right ascension (B1950)
43 A1 --- DE- Declination sign (B1950)
44- 45 I2 deg DEd Declination (B1950)
47- 48 I2 arcmin DEm Declination (B1950)
50- 51 I2 arcsec DEs Declination (B1950)
53- 57 F5.2 Jy F12um ? 12{mu}m flux density
58 A1 --- f_F12um [L] for lower limit
60- 65 F6.2 Jy F25um ? 25{mu}m flux density
66 A1 --- f_F25um [L] for lower limit
68- 74 F7.2 Jy F60um ? 60{mu}m flux density
75 A1 --- f_F60um [L] for lower limit
77- 83 F7.2 Jy F100um ? 100{mu}m flux density
84 A1 --- f_F100um [L] for lower limit
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Note (1): the additional digit is:
1 for class 0 YSO by Bachiller (1996ARA&A..34..111B)
2 for class 0 YSO by Mardones et al. (1997ApJ...489L..79F)
3 for PMS star by the criteria of Weintraub (1990ApJS...74..575W)
4 for PMS star from Herbig & Bell (1988, Cat. <V/73>)
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History: From ApJS electronic version
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(End) James Marcout, Patricia Bauer [CDS] 14-Sep-1999