2006A&A...460..709F


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.09CEST07:48:38

2006A&A...460..709F - Astronomy and Astrophysics, volume 460, 709-720 (2006/12-4)

Searching for massive pre-stellar cores through observations of N2H+ and N2D+.

FONTANI F., CASELLI P., CRAPSI A., CESARONI R., MOLINARI S., TESTI L. and BRAND J.

Abstract (from CDS):

We have measured the deuterium fractionation and the CO depletion factor (ratio between expected and observed CO abundance) in a sample of high-mass protostellar candidates, in order to understand whether the earliest evolutionary stages of high-mass stars have chemical characteristics similar to those of low-mass ones. It has been found that low-mass starless cores on the verge of star formation have large values both of the column density ratio N(N2D+)/N(N2H+) and of the CO depletion factor. With the IRAM-30 m telescope and the JCMT we have observed two rotational lines of N2H+ and N2D+, the (2-1) line of C17O and DCO+, and the sub-millimeter continuum towards a sample of 10 high-mass protostellar candidates. We have detected N2D+ emission in 7 of the 10 sources of our sample, and found an average value N(N2D+)/N(N2H+)∼0.015. This value is ∼3 orders of magnitude larger than the interstellar D/H ratio, indicating the presence of cold and dense gas, in which the physical-chemical conditions are similar to those observed in low-mass pre-stellar cores. The integrated CO depletion factors show that in the majority of the sources the expected CO abundances are larger than the observed values, with a median ratio of 3.2. In principle, the cold gas that generates the N2D+ emission can be the remnant of the massive molecular core in which the high-mass (proto-)star was born, not yet heated up by the central object. If so, our results indicate that the chemical properties of the clouds in which high-mass stars are born are similar to their low-mass counterparts. Alternatively, this cold gas could be located in one (or more) starless core (cores) near the protostellar object. Due to the poor angular resolution of our data, we cannot distinguish between the two scenarios.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: molecules

Simbad objects: 24

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Number of rows : 24

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 LDN 1521F DNe 04 28 39.3 +26 51 43           ~ 184 1
2 Bad 16 Y*O 04 30 50.2775823865 +23 00 08.771252817       14.95   F1 132 0
3 NGC 1985 RNe 05 37 47.8 +31 59 24           ~ 130 2
4 CPM 19 Y*O 05 40 24.4 +23 50 54           ~ 48 0
5 IRAS 05490+2658 Y*O 05 52 12.9 +26 59 33           ~ 49 0
6 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 283 1
7 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11613 0
8 IRAS 18144-1723 IR 18 17 24.4 -17 22 13           ~ 32 0
9 MSX6C G034.8211+00.3519 Y*O 18 53 38.2500 +01 50 24.001           ~ 50 0
10 IRAS 18517+0437 SFR 18 54 13.8 +04 41 32           ~ 56 0
11 SH 2-75 HII 18 59 13.6 +07 04 47   13.60 12.74     ~ 29 0
12 IRAS 19092+0841 Rad 19 11 37.4 +08 46 30           ~ 28 0
13 IRAS 20106+3545 IR 20 12 31.3 +35 54 46           ~ 16 0
14 IRAS 20126+4104 Y*O 20 14 25.8816186803 +41 13 36.869078243           B2.5-B0.5 397 0
15 IRAS 20205+3948 Y*O 20 22 21.9 +39 58 05           ~ 28 0
16 IRAS 20216+4107 cor 20 23 23.855 +41 17 40.49           ~ 53 0
17 IRAS 20278+3521 IR 20 29 46.8318549539 +35 31 42.045015044           ~ 17 0
18 IRAS 20343+4129 HII 20 36 07.1 +41 40 01           ~ 51 0
19 IRAS 22134+5834 Y*O 22 15 09.02616 +58 49 08.8608           ~ 68 0
20 LBN 102.79-00.92 HII 22 19 09.0 +56 04 45           ~ 100 0
21 IRAS 23139+5939 Y*O 23 16 10.39680 +59 55 28.2396           ~ 77 0
22 IRAS 23151+5912 HII 23 17 21.0 +59 28 49           ~ 93 0
23 Mol 160 Rad 23 40 54.5 +61 10 28           ~ 88 0
24 IRAS 23545+6508 * 23 57 05.2 +65 25 11           B 50 0

    Equat.    Gal    SGal    Ecl

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2020.08.09-07:48:38

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