2001ApJ...555...40G


Query : 2001ApJ...555...40G

2001ApJ...555...40G - Astrophys. J., 555, 40-57 (2001/July-1)

Far-infrared investigation of class 0 sources: line cooling.

GIANNINI T., NISINI B. and LORENZETTI D.

Abstract (from CDS):

We have investigated with the Long Wavelength Spectrometer (LWS) of the Infrared Space Observatory (ISO) the far-infrared spectra (43-197 µm) of a sample of 17 class 0 sources and their associated outflows. In addition to [O I] 63 µm, the pure rotational lines of abundant molecules such as CO, H2O, and OH are frequently observed in these sources, at variance with more evolved young stellar objects. We found, in agreement with previous studies conducted on individual sources, that the molecular line excitation arises from small regions, with typical sizes of 10–9 sr, of warm (200<T<2000 K) and dense gas (104<nH2<107 cm–3), compressed after the passage of shocks. In particular, we found slow, nondissociative shocks as the main mechanism at the origin of the molecular gas heating, while the bulk of the [O I] 63 µm line emission is due to the dissociative J-shock component arising from the Mach disk at the head of the protostellar jet, as testified by the fact that this line emission happens to be a good tracer of the source mass-loss rate. Large abundances of gas-phase H2O are commonly estimated, with values that appear to be correlated with the gas temperature. The total far-infrared (FIR) line cooling LFIR=L(O I)+L(CO)+L(H2O)+L(OH), which amounts to ∼10–2 to 10–1 L, is roughly equal to the outflow kinetic luminosity as estimated by means of millimeter molecular mapping. This circumstance demonstrates that the FIR line cooling can be a valid direct measure of the power deposited in the outflow, not affected by geometrical or opacity problems like the determination of Lkin or by extinction problems like the near-infrared shocked H2 emission. We finally remark that the strong molecular emission observed, and in particular H2O emission, is a peculiarity of the environments of class 0 sources. The present analysis shows that the ratio between FIR molecular line luminosity and bolometric luminosity (Lmol/Lbol) is always larger than ∼10–3 in class 0 objects. We suggest that this parameter could be used as a further criterion for identifying future class 0 candidates.

Abstract Copyright:

Journal keyword(s): Infrared: ISM - ISM: Jets and Outflows - ISM: Molecules - Stars: Formation - Stars: Mass Loss

Simbad objects: 40

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Number of rows : 40
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 SSTc2d J032536.4+304522 Y*O 03 25 36.49 +30 45 22.2           ~ 190 1
2 IRAS 03225+3034 IR 03 25 36.49 +30 45 22.2           ~ 154 1
3 LDN 1448NA smm 03 25 36.49 +30 45 22.2           ~ 178 1
4 IRAS F03226+3033 Y*O 03 25 38.83 +30 44 06.2           ~ 319 0
5 [SDA2014] West4 Y*O 03 25 38.83 +30 44 06.2           ~ 245 1
6 IRAS 03258+3104 Y*O 03 28 55.30 +31 14 27.8           ~ 160 1
7 [JCC87] IRAS 2A Y*O 03 28 55.55 +31 14 36.7           ~ 420 3
8 NAME HH 7-11 MMS 2 smm 03 29 03.056 +31 15 51.67           ~ 73 0
9 V* V512 Per Or* 03 29 03.7567945196 +31 16 03.959183877           ~ 364 0
10 [JCC87] IRAS 4A Y*O 03 29 10.49 +31 13 30.8           ~ 638 1
11 [JCC87] IRAS 4 FIR 03 29 10.9 +31 13 26           ~ 473 0
12 [JCC87] IRAS 4B Y*O 03 29 12.058 +31 13 02.05           ~ 573 0
13 IRAS 03282+3035 cor 03 31 20.98 +30 45 30.1           ~ 164 0
14 Ass Per OB 2 As* 03 42.2 +33 26           ~ 316 0
15 HH 211 cor 03 43 56.52 +32 00 52.8           ~ 314 0
16 NAME HH 211-mm Y*O 03 43 56.816 +32 00 50.06           ~ 61 1
17 * zet Per V* 03 54 07.9224751 +31 53 01.081262 2.19 2.97 2.85 2.71 2.62 B1Ib 822 0
18 LDN 1551 DNe 04 31 30.0 +18 12 30           ~ 782 1
19 LDN 1527 DNe 04 39 53 +25 45.0           ~ 538 0
20 HH 1C HH 05 36 20.68 -06 45 10.6           ~ 17 0
21 GBS-VLA J053622.86-064606.6 Y*O 05 36 22.84 -06 46 06.2           ~ 100 0
22 HH 2C HH 05 36 25.49 -06 47 07.3           ~ 18 0
23 LDN 1641 MoC 05 39.0 -07 00           ~ 444 0
24 [MCK88] NGC 2024 FIR 3 PoC 05 41 43.00 -01 54 24.0           ~ 49 0
25 NGC 2024 Cl* 05 41 43 -01 50.5           ~ 1092 1
26 [MCK88] NGC 2024 FIR 5 cor 05 41 44.6 -01 55 38           ~ 91 0
27 NAME HH 25MMS Y*O 05 46 07.8 -00 13 41           ~ 56 0
28 LMZ 3 IR 05 46 08.8 -00 10 47           ~ 85 0
29 NAME VLA 1623-243 Y*O 16 26 26.42 -24 24 30.0           ~ 389 0
30 [SSG2006] MMS002 smm 16 26 26.50 -24 24 30.9           ~ 241 0
31 IRAS 16293-2422 cor 16 32 22.56 -24 28 31.8           ~ 1112 1
32 NAME LDN 483-mm mm 18 17 29.8 -04 39 38           ~ 20 0
33 LDN 483 DNe 18 17 35 -04 39.8           ~ 236 0
34 NAME SH 2-68 FIR 1 cor 18 29 49.63 +01 15 21.9           ~ 245 2
35 NAME LDN 723-mm smm 19 17 53.70 +19 12 20.0           ~ 16 0
36 LDN 723 DNe 19 18 12 +19 13.6           ~ 153 0
37 LDN 663 DNe 19 36 55 +07 34.4           ~ 577 0
38 HH 375 Y*O 20 39 06.2 +68 02 15           ~ 170 0
39 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 515 0
40 NAME Cep E HII 23 03 12.779 +61 42 25.75           ~ 160 0

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2021.09.21-06:20:40

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