J/A+A/372/L41 NGC 2068/2071 protoclusters (Motte+, 2001)
A SCUBA survey of the NGC 2068/2071 protoclusters.
Motte F., Andre P., Ward-Thompson D., Bontemps S.
<Astron. Astrophys. 372, L41 (2001)>
=2001A&A...372L..41M 2001A&A...372L..41M
ADC_Keywords: Molecular clouds ; Photometry, infrared ; Radio continuum
Keywords: ISM: clouds - ISM: structure - dust - stars: formation -
stars: initial mass function - submillimeter
Description:
We report on a wide-field submillimeter continuum survey of the
NGC 2068/2071 protoclusters in the Orion B cloud complex. We used the
SCUBA bolometer array on JCMT to map a 32'x18' region in size
(∼4pcx2pc) at 850 and 450 microns. Our survey shows that the dense
cores mapped in CS(2-1) by Lada et al. (1991ApJ...368..432L 1991ApJ...368..432L) and
labelled with LBS numbers break up into 82 small-scale (∼5000AU)
fragments. The latter include 70 starless condensations, believed to
be the immediate progenitors of accreting protostars, and 5
circumstellar envelopes/disks around protostars. The nature of the 7
remaining cloud fragments is unclear because their dust continuum
emission is largely contaminated by line emission.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 82 Protocluster condensations identified in
NGC 2068/2071
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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- 10 A10 --- Name Condensation name
12- 13 I2 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
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 31 I2 arcsec DEs *Declination (J2000)
33- 37 I5 mJy Sint850 Integrated flux at 850 microns (350GHz) (1)
39- 43 I5 AU FWHM1 ? Deconvolved FWHM size (2)
44 A1 --- --- [x]
45- 49 I5 AU FWHM2 ? Deconvolved FWHM size (2)
50 A1 --- f_FWHM1 [u] u: unresolved
52 A1 --- l_Mass [<] Upper limit symbol
53- 56 F4.2 solMass Mass Condensation mass (3)
58- 60 F3.1 --- Sp+Index ? Submm spectral index (4)
62- 91 A30 --- Text Comments on the condensation
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Note on RAs, DEs:
The absolute positional accuracy is better than ∼5".
Note (1): Integrated flux at 850 microns estimated (after background
subtraction, see Motte et al., 1998A&A...336..150M 1998A&A...336..150M) over an area
twice the size of FWHM when convolved with the 13" beam. The absolute
calibration uncertainty is ∼20%. The typical rms noise is
∼22mJy*2*[(FWHM2+HPBW2)/HPBW2]1/2.
Note (2): Deconvolved FWHM size derived from a 2D-Gaussian fit to the
850microns map after background subtraction.
Note (3): Mass derived from the 850 microns integrated flux, Sint850.
Assumed dust temperature and opacity are
Td=15K and kappa850=0.01cm2/g for starless condensations,
Td=20-40K and kappa850=0.02cm2/g for protostellar envelopes.
Note (4): Spectral index alpha450850 (where S(nu) ∝ nu^alpha)
measured between 450 microns and 850 microns in an 18" beam at the
position of each condensation without background subtraction. The
typical error bar on alpha450850 is ±0.5. Since the background
emission often dominates and has a spectral index of ∼4, we estimate
that the intrinsic spectral indices of the condensations are lower
than the values listed here by ∼1 on average.
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Acknowledgements: Frederique Motte
Philippe Andre
(End) Frederique Motte [Caltech], Patricia Bauer [CDS] 22-Jun-2001