Far‐Infrared Investigation of Class 0 Sources: Line Cooling

Giannini, T.; Nisini, B.; Lorenzetti, D.

doi:10.1086/321451

Cited by 126 publications

(228 citation statements)

References 37 publications

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“…Given the uncertain baseline, this needs to be treated with caution. Figure 3 compares the OH fluxes from YSOs as measured here with PACS and in ISO observations of two additional sources, Ser SMM1 (Larsson et al 2002) and NGC 1333 IRAS 4 (Giannini et al 2001). Despite the wide range of luminosities and masses covered in our sample, the sources show surprisingly similar characteristics in terms of their OH emission: the OH 84 μm doublet is generally the strongest of the four, while the integrated intensity of the weakest doublet at 163 μm is roughly a factor of three lower.…”

Section: Discussionmentioning

confidence: 99%

“…For Ser SMM1, we use the average values of the fluxes presented by Larsson et al (2002). The data for NGC 1333 IRAS 4 are taken from Giannini et al (2001). Note that for NGC 1333 IRAS 4, we use the luminosity and mass of NGC 1333 IRAS 4A.…”

Section: Appendix A: Observational Detailsmentioning

confidence: 99%

“…Previous studies of OH FIR emission with the ISO showed that OH is one of the major molecular coolants in starforming regions (e.g. Giannini et al 2001). However, with a large beam of 80 , ISO was unable to resolve the central source from the outflows, preventing an assessment of the origin of the OH emission.…”

Section: Introductionmentioning

confidence: 99%

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Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Wampfler¹,

Herczeg

Bruderer³

et al. 2010

A&A

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Section: Discussionmentioning

confidence: 99%

Section: Appendix A: Observational Detailsmentioning

confidence: 99%

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Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Wampfler¹,

Herczeg

Bruderer³

et al. 2010

A&A

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“…Figures 10-14 are available in electronic form at http://www.aanda.org subsequently detected CO up to the 21-20 line (E u /k = 1300 K), along with rotationally excited H 2 O (up to 470 K) and OH (up to 620 K; Ceccarelli et al 1999;Giannini et al 1999Giannini et al , 2001Nisini et al 2002). The origin of this hot gas has been debated ever since.…”

Section: The Infrared Space Observatory (Iso)mentioning

confidence: 99%

ModellingHerschelobservations of hot molecular gas emission from embedded low-mass protostars

Visser

Kristensen

Bruderer

et al. 2012

A&A

119

185

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Aims. Young stars interact vigorously with their surroundings, as evident from the highly rotationally excited CO (up to E u /k = 4000 K) and H 2 O emission (up to 600 K) detected by the Herschel Space Observatory in embedded low-mass protostars. Our aim is to construct a model that reproduces the observations quantitatively, to investigate the origin of the emission, and to use the lines as probes of the various heating mechanisms. Methods. The model consists of a spherical envelope with a power-law density structure and a bipolar outflow cavity. Three heating mechanisms are considered: passive heating by the protostellar luminosity, ultraviolet irradiation of the outflow cavity walls, and small-scale C-type shocks along the cavity walls. Most of the model parameters are constrained from independent observations; the two remaining free parameters considered here are the protostellar UV luminosity and the shock velocity. Line fluxes are calculated for CO and H 2 O and compared to Herschel data and complementary ground-based data for the protostars NGC 1333 IRAS2A, HH 46 and DK Cha. The three sources are selected to span a range of evolutionary phases (early Stage 0 to late Stage I) and physical characteristics such as luminosity and envelope mass. Results. The bulk of the gas in the envelope, heated by the protostellar luminosity, accounts for 3-10% of the CO luminosity summed over all rotational lines up to J = 40-39; it is best probed by low-J CO isotopologue lines such as C 18 O 2-1 and 3-2. The UV-heated gas and the C-type shocks, probed by 12 CO 10-9 and higher-J lines, contribute 20-80% each. The model fits show a tentative evolutionary trend: the CO emission is dominated by shocks in the youngest source and by UV-heated gas in the oldest one. This trend is mainly driven by the lower envelope density in more evolved sources. The total H 2 O line luminosity in all cases is dominated by shocks (>99%). The exact percentages for both species are uncertain by at least a factor of 2 due to uncertainties in the gas temperature as function of the incident UV flux. However, on a qualitative level and within the context of our model, both UV-heated gas and C-type shocks are needed to reproduce the emission in far-infrared rotational lines of CO and H 2 O.

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“…Appendices and acknowledgements (pages 5 to 7) are only available in electronic form at http://www.aanda.org have been limited to the lowest rotational lines originating from levels up to 35 K. The ISO has detected strong far-infrared CO lines up to J u = 29 from Class 0 sources (Giannini et al 2001) but the emission is spatially unresolved in the large 80 beam. ISO also lacked the spectral resolution needed to separate the shocked and quiescent gas or to detect intrinsically-weaker 13 CO and C 18 O lines on top of the strong continuum.…”

Section: Most Ground-based Observations Of Co and Its Isotopologuesmentioning

confidence: 99%

Herschel/HIFI observations of high-JCO lines in the NGC 1333 low-mass star-forming region

Yıldız¹,

Dishoeck

Kristensen³

et al. 2010

A&A

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Herschel/HIFI observations of high-J lines (up to J u = 10) of 12 CO, 13 CO and C 18 O are presented toward three deeply embedded low-mass protostars, NGC 1333 IRAS 2A, IRAS 4A, and IRAS 4B, obtained as part of the Water In Star-forming regions with Herschel (WISH) key program. The spectrally-resolved HIFI data are complemented by ground-based observations of lower-J CO and isotopologue lines. The 12 CO 10-9 profiles are dominated by broad (FWHM 25-30 km s −1 ) emission. Radiative transfer models are used to constrain the temperature of this shocked gas to 100-200 K. Several CO and 13 CO line profiles also reveal a medium-broad component (FWHM5-10 km s −1 ), seen prominently in H 2 O lines. Column densities for both components are presented, providing a reference for determining abundances of other molecules in the same gas. The narrow C 18 O 9-8 lines probe the warmer part of the quiescent envelope. Their intensities require a jump in the CO abundance at an evaporation temperature around 25 K, thus providing new direct evidence for a CO ice evaporation zone around low-mass protostars.

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Far‐Infrared Investigation of Class 0 Sources: Line Cooling

Cited by 126 publications

References 37 publications

Herschelobservations of the hydroxyl radical (OH) in young stellar objects

Herschelobservations of the hydroxyl radical (OH) in young stellar objects

ModellingHerschelobservations of hot molecular gas emission from embedded low-mass protostars

Herschel/HIFI observations of high-JCO lines in the NGC 1333 low-mass star-forming region

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