J/A+A/588/A30 Properties of cores in OMC 2/3 (Sadavoy+, 2016)
Dust emissivity in the star-forming filament OMC 2/3.
Sadavoy S.I., Stutz A., Schnee S., Mason B., Di Francesco J., Friesen R.
<Astron. Astrophys. 588, A30 (2016)>
=2016A&A...588A..30S 2016A&A...588A..30S (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Millimetric/submm sources ; Infrared sources
Keywords: stars: formation - dust, extinction - ISM: clouds -
submillimeter: ISM
Abstract:
We present new measurements of the dust emissivity index, β, for
the high-mass, star-forming OMC 2/3 filament. We combined 160-500um
data from Herschel with long-wavelength observations at 2mm and fit
the spectral energy distributions across a≃2pc long, continuous
section of OMC 2/3 at 15000AU (0.08pc) resolution. With these data, we
measured β and reconstructed simultaneously the filtered-out
large-scale emission at 2mm. We implemented both variable and fixed
values of β, finding that β=1.7-1.8 provides the best fit
across most of OMC 2/3. These β values are consistent with a
similar analysis carried out with filtered Herschel data. Thus, we
show that β values derived from spatial filtered emission maps
agree well with those values from unfiltered data at the same
resolution. Our results contradict the very low β values (∼0.9)
previously measured in OMC 2/3 between 1.2mm and 3.3mm data, which we
attribute to elevated fluxes in the 3.3mm observations. Therefore, we
find no evidence of rapid, extensive dust grain growth in OMC 2/3.
Future studies with Herschel data and complementary ground-based
long-wavelength data can apply our technique to obtain reliable
determinations of β in nearby cold molecular clouds.
Description:
Physical properties of dense sources in the OMC 2/3 filament obtained
from fitting observed spectral energy distributions (SEDs) with
modified blackbody functions. Sources and their fluxes were identified
using the extraction code, getsources. SEDs were made using PACS and
SPIRE bands (160-500um) from Herschel and GISMO 2mm observations
from the IRAM 30m telescope. The source properties were determined
from the SEDs in two ways: (1) fitting for the dust temperature, and
(2) adopting a fixed dust temperature equal to the NH3 kinetic gas
temperature from the literature.
Objects:
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RA (2000) DE Designation(s)
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05 35 27 -05 10.1 OMC 2 = OMC 2
05 45 15 -05 00.3 OMC 3 = OMC 3
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 76 17 Source properties (updated table, 21/11/2022,
from corrigendum 2022A&A...666C...2S 2022A&A...666C...2S)
list.dat 88 12 Information on fits file
fits/* . 1 Individual fits file
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- ID Source Name (1)
7- 9 I3 --- HOPS ? HOPS ID number (2)
11 A1 --- Hflag [t] Flag for HOPS ID number (3)
13 I1 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 21 F4.1 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24 I1 deg DEd Declination (J2000)
26- 27 I2 arcmin DEm Declination (J2000)
29- 30 I2 arcsec DEs Declination (J2000)
32- 35 F4.1 K Td Dust temperature
37- 39 F3.1 K e_Td Error on dust temperature
41- 43 F3.1 --- b1 Dust emissivity index (beta)
45- 47 F3.1 --- e_b1 Error on dust emissivity index
49- 52 F4.1 Msun M1 Mass
54- 56 F3.1 Msun e_M1 Error on mass
58- 59 I2 K Tk ?=99 Kinetic gas temperature (4)
61- 63 F3.1 --- b2 ?=9.9 Dust emissivity index (beta) (4)
65- 67 F3.1 --- e_b2 ?=9.9 Error on dust emissivity index (4)
69- 72 F4.1 Msun M2 ?=9.9 Mass (4)
74- 76 F3.1 Msun e_M2 ?=9.9 Error on mass (4)
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Note (1): Names with MMS or FIR are from Chini et al. (1997ApJ...474L.135C 1997ApJ...474L.135C,
[CRW97] OMC-3 MMS NN or [MWZ90] OMC-2 FIR Na in Simbad) and
names with NW are from Nutter & Ward-Thompson (2007MNRAS.374.1413N 2007MNRAS.374.1413N,
where NN is the recno of the vizir catalog J/MNRAS/374/1413).
Note (2): ID numbers from the Herschel Orion Protostars Survey (HOPS) from
Fulan et al. (2015, submitted).
Note (3): Flag for HOPS associations: t = tentative association.
Note (4): SEDs were fit with the dust temperature fixed to the NH3-derived
kinetic gas temperature from Li et al. (2013ApJ...768L...5L 2013ApJ...768L...5L).
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 deg RAdeg ? Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg ? Declination of center (J2000)
20- 22 I3 --- Nx ? Number of pixels along X-axis
24- 26 I3 --- Ny ? Number of pixels along Y-axis
28- 30 I3 Kibyte size Size of FITS file
32- 66 A35 --- FileName Name of FITS file, in subdirectory fits
68- 88 A21 --- Ext Title of the extention
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Acknowledgements:
Sarah Sadavoty, sadavoy(at)mpia-hd.mpg.de
(End) Sarah Sadavoy [MPIA], Patricia Vannier [CDS] 27-Jan-2016