- ID:
- ivo://CDS.VizieR/J/A+A/547/A49
- Title:
- Herschel EPoS: high-mass overview
- Short Name:
- J/A+A/547/A49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stars are born deeply embedded in molecular clouds. In the earliest embedded phases, protostars emit the bulk of their radiation in the far-infrared wavelength range, where Herschel is perfectly suited to probe at high angular resolution and dynamic range. In the high-mass regime, the birthplaces of protostars are thought to be in the high-density structures known as infrared-dark clouds (IRDCs). While massive IRDCs are believed to have the right conditions to give rise to massive stars and clusters, the evolutionary sequence of this process is not well-characterized. As part of the Earliest Phases of Star formation (EPoS) Herschel guaranteed time key program, we isolate the embedded structures within IRDCs and other cold, massive molecular clouds. We present the full sample of 45 high-mass regions which were mapped at PACS 70, 100, and 160um and SPIRE 250, 350, and 500um. In the present paper, we characterize a population of cores which appear in the PACS bands and place them into context with their host molecular cloud and investigate their evolutionary stage.
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- ID:
- ivo://CDS.VizieR/J/ApJ/846/32
- Title:
- Herschel FIR spectra of GOALS galaxies
- Short Name:
- J/ApJ/846/32
- Date:
- 13 Dec 2021 06:52:25
- Publisher:
- CDS
- Description:
- We present an analysis of [OI]_63_, [OIII]_88_, [NII]_122_, and [CII]_158_ far-infrared (FIR) fine-structure line observations obtained with Herschel/PACS, for ~240 local luminous infrared galaxies (LIRGs) in the Great Observatories All-sky LIRG Survey. We find pronounced declines ("deficits") of line-to-FIR continuum emission for [NII]_122_, [OI]_63_, and [CII]_158_ as a function of FIR color and infrared luminosity surface density, {Sigma}_IR_. The median electron density of the ionized gas in LIRGs, based on the [NII]_122_/[NII]_205_ ratio, is n_e_=41cm^-3^. We find that the dispersion in the [CII]_158_ deficit of LIRGs is attributed to a varying fractional contribution of photodissociation regions (PDRs) to the observed [CII]_158_ emission, f([CII]_158_^PDR^)=[CII]_158_^PDR^/[CII]_158_, which increases from ~60% to ~95% in the warmest LIRGs. The [OI]_63_/[CII]_158_^PDR^ ratio is tightly correlated with the PDR gas kinetic temperature in sources where [OI]_63_ is not optically thick or self-absorbed. For each galaxy, we derive the average PDR hydrogen density, n_H_, and intensity of the interstellar radiation field, G, in units of G_0_ and find G/n_H_ ratios of ~0.1-50G_0_.cm^3^, with ULIRGs populating the upper end of the distribution. There is a relation between G/n_H_ and {Sigma}_IR_, showing a critical break at {Sigma}_IR_^*^~5x10^10^L_{sun}_/kpc^2^. Below {Sigma}_IR_^*^, G/n_H_ remains constant, ~0.32G_0_.cm^3^, and variations in {Sigma}_IR_ are driven by the number density of star-forming regions within a galaxy, with no change in their PDR properties. Above {Sigma}_IR_^*^, G/n_H_ increases rapidly with {Sigma}_IR_, signaling a departure from the typical PDR conditions found in normal star-forming galaxies toward more intense/harder radiation fields and compact geometries typical of starbursting sources.
- ID:
- ivo://CDS.VizieR/VI/139
- Title:
- Herschel Observation Log
- Short Name:
- VI/139
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Space Observatory (Herschel) is an ESA (European Space Agency) project with instruments funded by ESA member states. It was operated from May 2009 till April 2013, offering unprecedent observational capabilities in the far-infrared and submillimetre spectral range (55-671 microns). Herschel carried a 3.5m diameter passively cooled Cassegrain telescope. The science payload comprised three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI. Herschel successfully made over 37,000 scientific observations. Herschel Science Archive: The HSA is available at the Herschel Science Centre at http://herschel.esac.esa.int/Science_Archive.shtml Herschel helpdesk: http://herschel.esac.esa.int/esupport/ Herschel User Provided Data Products: http://herschel.esac.esa.int/UserProvidedDataProducts.shtml Postcard Server: http://archives.esac.esa.int/hsa/aio/doc/postcardGallery.html Observation Log: http://herschel.esac.esa.int/logrepgen/observationlist.do
- ID:
- ivo://CDS.VizieR/J/A+A/570/A113
- Title:
- Herschel/PACS imaging of {pi}^1^ Gru (HIP110478)
- Short Name:
- J/A+A/570/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Mass loss of Evolved StarS (MESS) sample observed with PACS on board the Herschel Space Observatory revealed that several asymptotic giant branch (AGB) stars are surrounded by an asymmetric circumstellar envelope (CSE) whose morphology is most likely caused by the interaction with a stellar companion. The evolution of AGB stars in binary systems plays a crucial role in understanding the formation of asymmetries in planetary nebulae (PNe), but at present, only a handful of cases are known where the interaction of a companion with the stellar AGB wind is observed. We probe the environment of the very evolved AGB star pi^1^ Gruis on large and small scales to identify the triggers of the observed asymmetries.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A109
- Title:
- Herschel/PACS spectra of 48 evolved stars
- Short Name:
- J/A+A/565/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 48 Herschel/PACS spectra of evolved stars in the wavelength range of 67-72um. This wavelength range covers the 69mu band of crystalline olivine (Mg_2-2x_Fe_(2x)_SiO_4_). The width and wavelength position of this band are sensitive to the temperature and composition of the crystalline olivine. Our sample covers a wide range of objects: from high mass-loss rate AGB stars (OH/IR stars, dM/dt>=10^-5^M_{sun}_/yr), through post-AGB stars with and without circumbinary disks, to planetary nebulae and even a few massive evolved stars. The goal of this study is to exploit the spectral properties of the 69um band to determine the composition and temperature of the crystalline olivine. Since the objects cover a range of evolutionary phases, we study the physical and chemical properties in this range of physical environments. We fit the 69um band and use its width and position to probe the composition and temperature of the crystalline olivine. For 27 sources in the sample, we detected the 69um band of crystalline olivine (Mg_2-2x_Fe_(2x)_SiO_4_). The 69um band shows that all the sources produce pure forsterite grains containing no iron in their lattice structure. The temperature of the crystalline olivine as indicated by the 69um band, shows that on average the temperature of the crystalline olivine is highest in the group of OH/IR stars and the post-AGB stars with confirmed Keplerian disks. The temperature is lower for the other post-AGB stars and lowest for the planetary nebulae. A couple of the detected 69um bands are broader than those of pure magnesium-rich crystalline olivine, which we show can be due to a temperature gradient in the circumstellar environment of these stars. The disk sources in our sample with crystalline olivine are very diverse. They show either no 69um band, a moderately strong band, or a very strong band, together with a temperature for the crystalline olivine in their disk that is either very warm (~600K), moderately warm (~200K), or cold (~120K), respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/116
- Title:
- Herschel spectra of 11 very low mass stars
- Short Name:
- J/ApJ/841/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The properties of disks around brown dwarfs and very low mass stars (hereafter VLMOs) provide important boundary conditions on the process of planet formation and inform us about the numbers and masses of planets than can form in this regime. We use the Herschel Space Observatory PACS spectrometer to measure the continuum and [OI]63{mu}m line emission toward 11 VLMOs with known disks in the Taurus and Chamaeleon I star-forming regions. We fit radiative transfer models to the spectral energy distributions of these sources. Additionally, we carry out a grid of radiative transfer models run in a regime that connects the luminosity of our sources with brighter T Tauri stars. We find that VLMO disks with sizes 1.3-78au, smaller than typical T Tauri disks, fit well the spectral energy distributions assuming that disk geometry and dust properties are stellar mass independent. Reducing the disk size increases the disk temperature, and we show that VLMOs do not follow previously derived disk temperature-stellar luminosity relationships if the disk outer radius scales with stellar mass. Only 2 out of 11 sources are detected in [OI] despite a better sensitivity than was achieved for T Tauri stars, suggesting that VLMO disks are underluminous. Using thermochemical models, we show that smaller disks can lead to the unexpected [OI]63{mu}m nondetections in our sample. The disk outer radius is an important factor in determining the gas and dust observables.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/105
- Title:
- Herschel/SPIRE FTS [CI] lines in KINGFISH gal.
- Short Name:
- J/ApJ/887/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present resolved [CI] line intensities of 18 nearby galaxies observed with the SPIRE FTS spectrometer on the Herschel Space Observatory. We use these data along with resolved CO line intensities from J_up_=1 to 7 to interpret what phase of the interstellar medium the [CI] lines trace within typical local galaxies. A tight, linear relation is found between the intensities of the CO(4-3) and [CI](2-1) lines; we hypothesize this is due to the similar upper level temperature of these two lines. We modeled the [CI] and CO line emission using large-velocity gradient models combined with an empirical template. According to this modeling, the [CI](1-0) line is clearly dominated by the low-excitation component. We determine [CI] to molecular mass conversion factors for both the [CI](1-0) and [CI](2-1) lines, with mean values of {alpha}_[CI](1-0)_=7.3M_{sun}_/K/km.s/pc^2^ and {alpha}_[CI](2-1)_=34M_{sun}_/K/km.s/pc^2^ with logarithmic root-mean-square spreads of 0.20 and 0.32dex, respectively. The similar spread of {alpha}_[CI](1-0)_ to {alpha}_CO_ (derived using the CO(2-1) line) suggests that [CI](1-0) may be just as good a tracer of cold molecular gas as CO(2-1) in galaxies of this type. On the other hand, the wider spread of {alpha}_[CI](2-1)_ and the tight relation found between [CI](2-1) and CO(4-3) suggest that much of the [CI](2-1) emission may originate in warmer molecular gas.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/1
- Title:
- Herschel SPIRE/FTS 194-671um survey of GOALS LIRGs
- Short Name:
- J/ApJS/230/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a Herschel Space Observatory 194-671{mu}m spectroscopic survey of a sample of 121 local luminous infrared galaxies and report the fluxes of the CO J to J-1 rotational transitions for 4<=J<=13, the [NII] 205{mu}m line, the [CI] lines at 609 and 370{mu}m, as well as additional and usually fainter lines. The CO spectral line energy distributions (SLEDs) presented here are consistent with our earlier work, which was based on a smaller sample, that calls for two distinct molecular gas components in general: (i) a cold component, which emits CO lines primarily at J<~4 and likely represents the same gas phase traced by CO (1-0), and (ii) a warm component, which dominates over the mid-J regime (4<J<~10) and is intimately related to current star formation. We present evidence that the CO line emission associated with an active galactic nucleus is significant only at J>10. The flux ratios of the two [CI] lines imply modest excitation temperatures of 15-30K; the [CI] 370{mu}m line scales more linearly in flux with CO (4-3) than with CO (7-6). These findings suggest that the [CI] emission is predominantly associated with the gas component defined in (i) above. Our analysis of the stacked spectra in different far-infrared (FIR) color bins reveals an evolution of the SLED of the rotational transitions of H_2_O vapor as a function of the FIR color in a direction consistent with infrared photon pumping.
- ID:
- ivo://CDS.VizieR/J/A+A/573/A129
- Title:
- HeViCS. SPIRE point-source catalogs
- Short Name:
- J/A+A/573/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present three independent catalogs of point-sources extracted from SPIRE images at 250, 350, and 500 micron, acquired with the Herschel Space Observatory as a part of the Herschel Virgo Cluster Survey (HeViCS). The catalogs have been cross-correlated to consistently extract the photometry at SPIRE wavelengths for each object. Sources have been detected using an iterative loop. The source positions are determined by estimating the likelihood to be a real source for each peak on the maps, according to the criterion defined in the sourceExtractorSussextractor task. The flux densities are estimated using the sourceExtractorTimeline, a timeline-based point source fitter that also determines the fitting procedure with the width of the Gaussian that best reproduces the source considered. Afterwards, each source is subtracted from the maps, removing a Gaussian function in every position with the full width half maximum equal to that estimated in sourceExtractorTimeline.
- ID:
- ivo://CDS.VizieR/J/A+A/597/A114
- Title:
- Hi-GAL cluster candidates physical properties
- Short Name:
- J/A+A/597/A114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aims are to investigate the clustering of the far-infrared sources from the Herschel infrared Galactic Plane Survey (Hi-GAL) in the Galactic longitude range of -71 to 67{deg}. These clumps, and their spatial distribution, are an imprint of the original conditions within a molecular cloud. This will produce a catalogue of over-densities. The minimum spanning tree (MST) method was used to identify the over-densities in two dimensions. The catalogue was further refined by folding in heliocentric distances, resulting in more reliable over-densities, which are cluster candidates. We found 1633 over-densities with more than ten members. Of these, 496 are defined as cluster candidates because of the reliability of the distances, with a further 1,137 potential cluster candidates. The spatial distributions of the cluster candidates are different in the first and fourth quadrants, with all clusters following the spiral structure of the Milky Way. The cluster candidates are fractal. The clump mass functions of the clustered and isolated are statistically indistinguishable from each other and are consistent with Kroupa's initial mass function.
