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
We present Herschel PACS photometry of 17 B- to M-type stars in the 30Myr old Tucana-Horologium Association. This work is part of the Herschel Open Time Key Programme "Gas in Protoplanetary Systems" (GASPS). 6 of the 17 targets were found to have infrared excesses significantly greater than the expected stellar IR fluxes, including a previously unknown disk around HD30051. These six debris disks were fitted with single-temperature blackbody models to estimate the temperatures and abundances of the dust in the systems. For the five stars that show excess emission in the Herschel PACS photometry and also have Spitzer IRS spectra, we fit the data with models of optically thin debris disks with realistic grain properties in order to better estimate the disk parameters. The model is determined by a set of six parameters: surface density index, grain size distribution index, minimum and maximum grain sizes, and the inner and outer radii of the disk. The best-fitting parameters give us constraints on the geometry of the dust in these systems, as well as lower limits to the total dust masses. The HD105 disk was further constrained by fitting marginally resolved PACS 70{mu}m imaging.
Herschel obs. of major-merger pairs of z<0.1 galaxies
Short Name:
J/ApJS/222/16
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Herschel PACS and SPIRE far-infrared (FIR) and submillimeter imaging observations for a large K-band selected sample of 88 close major-merger pairs of galaxies (H-KPAIRs) in 6 photometric bands (70, 100, 160, 250, 350, and 500{mu}m). Among 132 spiral galaxies in the 44 spiral-spiral (S+S) pairs and 44 spiral-elliptical (S+E) pairs, 113 are detected in at least 1 Herschel band. The star formation rate (SFR) and dust mass (M_dust_) are derived from the IR SED fitting. The mass of total gas (M_gas_) is estimated by assuming a constant dust-to-gas mass ratio of 0.01. Star-forming spiral galaxies (SFGs) in S+S pairs show significant enhancements in both specific star formation rate (sSFR) and star formation efficiency (SFE), while having nearly the same gas mass compared to control galaxies. On the other hand, for SFGs in S+E pairs, there is no significant sSFR enhancement and the mean SFE enhancement is significantly lower than that of SFGs in S+S pairs. This suggests an important role for the disk-disk collision in the interaction-induced star formation. The M_gas_ of SFGs in S+E pairs is marginally lower than that of their counterparts in both S+S pairs and the control sample. Paired galaxies with and without interaction signs do not differ significantly in their mean sSFR and SFE. As found in previous works, this much larger sample confirms that the primary and secondary spirals in S+S pairs follow a Holmberg effect correlation on sSFR.
We analyze Herschel Space Observatory observations of 104 young stellar objects with protoplanetary disks in the ~1.5Myr star-forming region Lynds 1641 (L1641) within the Orion A Molecular Cloud. We present spectral energy distributions from the optical to the far-infrared including new photometry from the Herschel Photodetector Array Camera and Spectrometer at 70{mu}m. Our sample, taken as part of the Herschel Orion Protostar Survey, contains 24 transitional disks, 8 of which we identify for the first time in this work. We analyze the full disks (FDs) with irradiated accretion disk models to infer dust settling properties. Using forward modeling to reproduce the observed n_Ks-[70]_ index for the FD sample, we find the observed disk indices are consistent with models that have depletion of dust in the upper layers of the disk relative to the midplane, indicating significant dust settling. We perform the same analysis on FDs in Taurus with Herschel data and find that Taurus is slightly more evolved, although both samples show signs of dust settling. These results add to the growing literature that significant dust evolution can occur in disks by ~1.5Myr.
Herschel-PACS and -SPIRE spectroscopy of 70 objects
Short Name:
J/AJ/151/75
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the COPS-DIGIT-FOOSH (CDF) Herschel spectroscopy data product archive, and related ancillary data products, along with data fidelity assessments, and a user-created archive in collaboration with the Herschel-PACS and SPIRE ICC groups. Our products include datacubes, contour maps, automated line fitting results, and best 1D spectra products for all protostellar and disk sources observed with PACS in RangeScan mode for two observing programs: the DIGIT Open Time Key Program (KPOT\_nevans\_1 and SDP\_nevans\_1; PI: N. Evans), and the FOOSH Open Time Program (OT1\_jgreen02\_2; PI: J. Green). In addition, we provide our best SPIRE-FTS spectroscopic products for the COPS Open Time Program (OT2\_jgreen02\_6; PI: J. Green) and FOOSH sources. We include details of data processing, descriptions of output products, and tests of their reliability for user applications. We identify the parts of the data set to be used with caution. The resulting absolute flux calibration has improved in almost all cases. Compared to previous reductions, the resulting rotational temperatures and numbers of CO molecules have changed substantially in some sources. On average, however, the rotational temperatures have not changed substantially (<2%), but the number of warm (T_rot_~300K) CO molecules has increased by about 18%.
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.
A detailed analysis of Herschel-PACS observations at the North Ecliptic Pole has been made. High quality maps, covering an area of 0.44 square degrees, are produced and then used to derive new candidate source lists. A rigorous quality control pipeline has been used to create final legacy catalogues in the PACS Green 100um and Red 160um bands, containing 1385 and 630 sources respectively. These catalogues reach to more than twice the depth of the current archival Herschel/PACS Point Source Catalogue detecting 401 and 270 more sources in the short and long wavelength bands respectively. These counts have been used to construct galaxy source counts that extend down to flux densities of 6mJy and 19mJy (50% completeness) in the Green 100 micron and Red 160 micron bands respectively. These source counts are consistent with previously published PACS number counts in other fields across the sky. The source counts have been compared with galaxy evolution models identifying a population of luminous infrared galaxies as responsible for the bulk of the galaxy evolution over the flux range (5-100mJy) spanned by the observed counts, contributing approximate fractions of 50% and 60% to the cosmic infrared background (CIRB) at 100um and 160um respectively.
The Herschel Space Observatory was the fourth cornerstone mission in the European Space Agency (ESA) science programme. It had excellent broad band imaging capabilities in the far-infrared (FIR) and sub-millimetre part of the electromagnetic spectrum. Although the spacecraft finished observing in 2013, it left a large legacy dataset that is far from having been fully explored and still has a great potential for new scientific discoveries. The PACS and SPIRE photometric cameras observed about 8% of the sky in six different wavebands. This document describes the Herschel/PACS Point Source Catalogue (HPPSC), a FIR catalogue based on the broad-band photometric observations of the PACS instrument with filters centred at 70, 100 and 160um. We analysed all combined, Level 2.5/Level 3 Herschel/PACS photometric observations including 682 Parallel Mode, 12932 nominal mode and 1644 SSO maps. The PACS photometer maps that we produced were generated by applying the JScanam task of the Herschel Interactive Processing Environment (HIPE) v13.0.0. Sources were identified with the HIPE implementation of SUSSEXtractor, and the flux densities obtained by aperture photometry. We found a total of 108319 point sources that are considered to be reliable in the 70um maps, 131322 at 100um and 251392 point sources in the 160um maps. In addition, our quality control algorithm identified 546587 candidate sources that were found to be extended and 7185160 features which did not pass the signal-to-noise and other criteria to be considered reliable sources. These sources were included in the Extended Source List and Rejected Source List of the HPPSC, respectively. The calculated completeness and photometric accuracy values are based on simulations, where artificial sources were injected into the observational timeline with well controlled flux density values. The actual completeness is a complex function of the source flux, photometric band and the background complexity.
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.
We present a Herschel/Spectral and Photometric Imaging Receiver (SPIRE) survey of three protoclusters at z=2-3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours (S_350_/S_250_ and S_500_/S_350_) of 250{mu}m sources, we selected high-redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4{sigma} overdensity of six SPIRE sources around 4.5-arcmin (~2.2Mpc) from a density peak of H {alpha} emitters at z=2.2. In the HS1700 field, we found a 5{sigma} overdensity of eight SPIRE sources around 2.1-arcmin (~1.0Mpc) from a density peak of Lyman-break galaxies at z=2.3. We did not find any significant overdensities in SSA22 field, but we found three 500 {mu}m sources are concentrated 3-arcmin (~1.4Mpc) east to the Ly {alpha} emitters overdensity. If all the SPIRE sources in these three overdensities are associated with protoclusters, the inferred star formation rate densities are 10^3^-10^4^ times higher than the average value at the same redshifts. This suggests that dusty star formation activity could be very strongly enhanced in z~2-3 protoclusters. Further observations are needed to confirm the redshifts of the SPIRE sources and to investigate what processes enhance the dusty star formation activity in z~2-3 protoclusters.