2013A&A...552A.141K


C.D.S. - SIMBAD4 rel 1.7 - 2020.09.25CEST20:55:43

2013A&A...552A.141K - Astronomy and Astrophysics, volume 552A, 141-141 (2013/4-1)

Water in star-forming regions with Herschel (WISH). III. Far-infrared cooling lines in low-mass young stellar objects.

KARSKA A., HERCZEG G.J., VAN DISHOECK E.F., WAMPFLER S.F., KRISTENSEN L.E., GOICOECHEA J.R., VISSER R., NISINI B., SAN JOSE-GARCIA I., BRUDERER S., SNIADY P., DOTY S., FEDELE D., YILDIZ U.A., BENZ A.O., BERGIN E., CASELLI P., HERPIN F., HOGERHEIJDE M.R., JOHNSTONE D., JORGENSEN J.K., LISEAU R., TAFALLA M., VAN DER TAK F. and WYROWSKI F.

Abstract (from CDS):

Understanding the physical phenomena involved in the earlierst stages of protostellar evolution requires knowledge of the heating and cooling processes that occur in the surroundings of a young stellar object. Spatially resolved information from its constituent gas and dust provides the necessary constraints to distinguish between different theories of accretion energy dissipation into the envelope. Our aims are to quantify the far-infrared line emission from low-mass protostars and the contribution of different atomic and molecular species to the gas cooling budget, to determine the spatial extent of the emission, and to investigate the underlying excitation conditions. Analysis of the line cooling will help us characterize the evolution of the relevant physical processes as the protostar ages. Far-infrared Herschel-PACS spectra of 18 low-mass protostars of various luminosities and evolutionary stages are studied in the context of the WISH key program. For most targets, the spectra include many wavelength intervals selected to cover specific CO, H2O, OH, and atomic lines. For four targets the spectra span the entire 55-200µm region. The PACS field-of-view covers ∼47" with the resolution of 9.4". Most of the protostars in our sample show strong atomic and molecular far-infrared emission. Water is detected in 17 out of 18 objects (except TMC1A), including 5 Class I sources. The high-excitation H2O 818-707 63.3µm line (Eu/kB=1071K) is detected in 7 sources. CO transitions from J=14-13 up to J=49-48 are found and show two distinct temperature components on Boltzmann diagrams with rotational temperatures of ∼350K and ∼700K. H2O has typical excitation temperatures of ∼150K. Emission from both Class 0 and I sources is usually spatially extended along the outflow direction but with a pattern that depends on the species and the transition. In the extended sources, emission is stronger off source and extended on ≥10000AU scales; in the compact sample, more than half of the flux originates within 1000AU of the protostar. The H2O line fluxes correlate strongly with those of the high-J CO lines, both for the full array and for the central position, as well as with the bolometric luminosity and envelope mass. They correlate less strongly with OH fluxes and not with [OI] fluxes. In contrast, [OI] and OH often peak together at the central position. The PACS data probe at least two physical components. The H2O and CO emission very likely arises in non-dissociative (irradiated) shocks along the outflow walls with a range of pre-shock densities. Some OH is also associated with this component, most likely resulting from H2O photodissociation. UV-heated gas contributes only a minor fraction to the CO emission observed by PACS, based on the strong correlation between the shock-dominated CO 24-23 line and the CO 14-13 line. [OI] and some of the OH emission probe dissociative shocks in the inner envelope. The total far-infrared cooling is dominated by H2O and CO, with the fraction contributed by [OI] increasing for Class I sources. Consistent with previous studies, the ratio of total far-infrared line emission over bolometric luminosity decreases with the evolutionary state.

Abstract Copyright:

Journal keyword(s): infrared: ISM - ISM: jets and outflows - stars: protostars - molecular processes - astrochemistry

Simbad objects: 25

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Number of rows : 25

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 IRAS 03258+3104 Y*O 03 28 55.30 +31 14 27.8           ~ 159 1
2 [JCC87] IRAS 2A Y*O 03 28 55.55 +31 14 36.7           ~ 398 3
3 [JCC87] IRAS 4A Y*O 03 29 10.49 +31 13 30.8           ~ 605 1
4 [JCC87] IRAS 4 FIR 03 29 10.9 +31 13 26           ~ 467 0
5 [JCC87] IRAS 4B Y*O 03 29 12.058 +31 13 02.05           ~ 559 0
6 LDN 1489 DNe 04 04 47.5 +26 19 42           ~ 197 0
7 V* DG Tau Or* 04 27 04.6913654419 +26 06 16.041555299 13.57 13.97 10.50 12.28   K6Ve 930 1
8 IRAS 04361+2547 Y*O 04 39 13.89767 +25 53 20.6340           ~ 185 1
9 IRAS 04365+2535 Y*O 04 39 35.19360 +25 41 44.7252           ~ 241 0
10 LDN 1527 DNe 04 39 53 +25 45.0           ~ 506 0
11 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3532 0
12 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1372 0
13 V* RW Aur TT* 05 07 49.5662483 +30 24 05.177426   10.86 9.60 9.95   K1/5e+K5e 714 0
14 2MASS J08254384-5100326 Y*O 08 25 43.85 -51 00 32.7           ~ 298 1
15 IRAS 11051-7706 Y*O 11 06 46.025 -77 22 29.67           ~ 71 0
16 IRAS 11057-7706 Y*O 11 07 09.19896 -77 23 04.9920           ~ 59 0
17 BHR 71 MoC 12 01 36.810 -65 08 49.22           ~ 120 0
18 IRAS 15398-3359 Y*? 15 43 02.21016 -34 09 07.7112       18.38 21.72 ~ 130 0
19 HBC 650 TT* 16 34 29.32 -15 47 01.4           K3.0 165 2
20 LDN 483 DNe 18 17 35 -04 39.8           ~ 214 0
21 NAME SH 2-68 FIR 1 cor 18 29 49.63 +01 15 21.9           ~ 238 2
22 NAME Serpens SMM 4 cor 18 29 57.1 +01 13 15           ~ 123 0
23 IRAS 18274+0112 Y*O 18 29 57.73680 +01 14 05.6940           M4: 136 2
24 NAME SERPENS SMM 3 smm 18 29 59.7 +01 14 00           ~ 85 1
25 LDN 723 DNe 19 18 12 +19 13.6           ~ 153 0

    Equat.    Gal    SGal    Ecl

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2020.09.25-20:55:43

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