- ID:
- ivo://CDS.VizieR/J/ApJ/885/74
- Title:
- 1340 Helium rich white dwarfs in the Gaia era
- Short Name:
- J/ApJ/885/74
- Date:
- 09 Mar 2022 22:00:00
- Publisher:
- CDS
- Description:
- We present an analysis of 1023 DBZ/DZ(A) and 319 DQ white dwarf stars taken from the Montreal White Dwarf Database. This represents a significant increase over the previous comprehensive studies on these types of objects. We use new trigonometric parallax measurements from the Gaia second data release, together with photometry from the Sloan Digital Sky Survey, Pan-STARRS, Gaia, or BVRI from the literature, which allow the determination of the mass for the majority of the objects in our sample. We use the photometric and spectroscopic techniques with our recently improved model atmospheres code, which include high-density effects, to accurately determine the effective temperature, surface gravity, and heavy-element abundances for each object. We study the abundance of hydrogen in DBZ/DZ white dwarfs and the properties of the accreted planetesimals. We explore the nature of the second sequence of DQ stars using proper motions from Gaia and highlight evidence of crystallization in massive DQ stars. We also present mass distributions for both spectral types. Finally, we discuss the implications of our findings in the context of the spectral evolution of white dwarfs and provide the atmospheric parameters for each star.
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- ID:
- ivo://CDS.VizieR/J/AJ/118/1043
- Title:
- Herbig Ae/Be stars catalog
- Short Name:
- J/AJ/118/1043
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- UBVR photometric monitoring of Herbig Ae/Be stars and some related objects has been carried out at Maidanak Observatory in Uzbekistan since 1983. More than 71,000 observations of about 230 stars have been obtained and are made available for anonymous ftp. Virtually all Herbig Ae/Be stars observed are irregular variables (called "UXors" after UX Ori), but there is a wide range of amplitudes from barely detectable to more than 4mag in V. Our data confirm the results of previous studies, which indicate that large-amplitude variability is confined to stars with spectral types later than B8. The distribution of variability ranges is quite similar to what is seen in classical T Tauri stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/236/30
- Title:
- Herschel-ATLAS (H-ATLAS) DR2
- Short Name:
- J/ApJS/236/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) is a survey of 660deg^2^ with the PACS and SPIRE cameras in five photometric bands: 100, 160, 250, 350, and 500{mu}m. This is the second of three papers describing the data release for the large fields at the south and north Galactic poles (NGP and SGP). In this paper we describe the catalogs of far-infrared and submillimeter sources for the NGP and SGP, which cover 177.1deg^2^ and 303.4deg^2^, respectively. The catalogs contain 118980 sources for the NGP field and 193527 sources for the SGP field detected at more than 4{sigma} significance in any of the 250, 350, or 500{mu}m bands. The source detection is based on the 250{mu}m map, and we present photometry in all five bands for each source, including aperture photometry for sources known to be extended. The rms positional accuracy for the faintest sources is about 2.4" in both RA and DEC. We present a statistical analysis of the catalogs and discuss the practical issues-completeness, reliability, flux boosting, accuracy of positions, accuracy of flux measurements-necessary to use the catalogs for astronomical projects.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/100
- Title:
- Herschel FIR observations of NGC3603
- Short Name:
- J/ApJ/799/100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the giant H II region around the NGC 3603 young stellar cluster (YC) with the five broad bands (70, 160, 250, 350, 500{mu}m) of the SPIRE and PACS instruments, on board the Herschel Space Observatory. Together with what is currently known of the stellar, atomic, molecular, and warm dust components, this additional and crucial information should allow us to better understand the details of the star-formation history in this region. The main objective of the investigation is to study, at high spatial resolution, the distribution and main physical characteristics of the cold dust. By reconstructing the temperature and density maps, we found, respectively, a mean value of 36K and log_10_N_H_=22.0+/-0.1/cm2. We carried out a photometric analysis detecting 107 point-like sources, mostly confined to the north and south of the cluster. By comparing our data with spectral energy distribution models, we found that 35 sources are well represented by young stellar objects in early evolutionary phases, from Class 0 to Class I. The Herschel detections also provided far-IR counterparts for 4 H_2_O masers and 11 objects previously known from mid-IR observations. The existence of so many embedded sources confirms the hypothesis of intense and ongoing star-formation activity in the region around NGC 3603 YC.
- ID:
- ivo://CDS.VizieR/J/ApJ/745/95
- Title:
- Herschel FIR & submm photometry of KINGFISH sample
- Short Name:
- J/ApJ/745/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New far-infrared and submillimeter photometry from the Herschel Space Observatory is presented for 61 nearby galaxies from the Key Insights on Nearby Galaxies: A Far-Infrared Survey with Herschel (KINGFISH) sample. The spatially integrated fluxes are largely consistent with expectations based on Spitzer far-infrared photometry and extrapolations to longer wavelengths using popular dust emission models. Dwarf irregular galaxies are notable exceptions, as already noted by other authors, as their 500{mu}m emission shows evidence for a submillimeter excess. In addition, the fraction of dust heating attributed to intense radiation fields associated with photodissociation regions is found to be (21+/-4)% larger when Herschel data are included in the analysis. Dust masses obtained from the dust emission models of Draine & Li (2007ApJ...657..810D) are found to be on average nearly a factor of two higher than those based on single-temperature modified blackbodies, as single blackbody curves do not capture the full range of dust temperatures inherent to any galaxy. The discrepancy is largest for galaxies exhibiting the coolest far-infrared colors.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/1571
- Title:
- Herschel fluxes of Fornax galaxies
- Short Name:
- J/MNRAS/440/1571
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Herschel Fornax Cluster Survey is a deep, far-infrared (FIR) survey of the Fornax cluster. The survey is in five Herschel bands (100-500{mu}m) and covers an area of 16deg^2^ centred on NGC 1399. This paper presents photometry, detection rates, dust masses, and temperatures using an optically selected sample from the Fornax Cluster Catalogue. Our results are compared with those previously obtained using data from the Herschel Virgo Cluster Survey (HeViCS). In Fornax, we detect 30 of the 237 (13%) optically selected galaxies in at least one Herschel band. The global detection rates are significantly lower than Virgo, reflecting the morphological make up of each cluster - Fornax has a lower fraction of late-type galaxies. For galaxies detected in at least three bands, we fitted a modified blackbody with a {beta}=2 emissivity. Detected early-type galaxies (E/S0) have a mean dust mass, temperature, and dust-to-stars ratio of log10(<M_dust_>/M_{sun}_)=5.82+/-0.20, <T_dust_>=20.82+/-1.77K, and log_10_(M_dust_/M_stars_)=-3.87+/-0.28, respectively. Late-type galaxies (Sa to Sd) have a mean dust mass, temperature, and dust-to-stars ratio of log10(M_dust_>/M_{sun}_)=6.54+/-0.19, <T_dust_>=17.47+/-0.97K, and log_10_(M_dust_/M_stars_)=-2.93+/-0.09, respectively. The different cluster environments seem to have had little effect on the FIR properties of the galaxies and so we conclude that any environment-dependent evolution has taken place before the cluster was assembled.
- ID:
- ivo://CDS.VizieR/J/AJ/146/62
- Title:
- HERschel HERITAGE in Magellanic Clouds
- Short Name:
- J/AJ/146/62
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an overview of the HERschel Inventory of The Agents of Galaxy Evolution (HERITAGE) in the Magellanic Clouds project, which is a Herschel Space Observatory open time key program. We mapped the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) at 100, 160, 250, 350, and 500{mu}m with the Spectral and Photometric Imaging Receiver (SPIRE) and Photodetector Array Camera and Spectrometer (PACS) instruments on board Herschel using the SPIRE/PACS parallel mode. The overriding science goal of HERITAGE is to study the life cycle of matter as traced by dust in the LMC and SMC. The far-infrared and submillimeter emission is an effective tracer of the interstellar medium (ISM) dust, the most deeply embedded young stellar objects (YSOs), and the dust ejected by the most massive stars. We describe in detail the data processing, particularly for the PACS data, which required some custom steps because of the large angular extent of a single observational unit and overall the large amount of data to be processed as an ensemble. We report total global fluxes for the LMC and SMC and demonstrate their agreement with measurements by prior missions. The HERITAGE maps of the LMC and SMC are dominated by the ISM dust emission and bear most resemblance to the tracers of ISM gas rather than the stellar content of the galaxies. We describe the point source extraction processing and the criteria used to establish a catalog for each waveband for the HERITAGE program. The 250{mu}m band is the most sensitive and the source catalogs for this band have ~25,000 objects for the LMC and ~5500 objects for the SMC. These data enable studies of ISM dust properties, submillimeter excess dust emission, dust-to-gas ratio, Class 0 YSO candidates, dusty massive evolved stars, supernova remnants (including SN1987A), HII regions, and dust evolution in the LMC and SMC. All images and catalogs are delivered to the Herschel Science Center as part of the community support aspects of the project. These HERITAGE images and catalogs provide an excellent basis for future research and follow up with other facilities.
- ID:
- ivo://CDS.VizieR/J/AJ/148/124
- Title:
- Herschel key program Heritage
- Short Name:
- J/AJ/148/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations from the HERschel Inventory of the Agents of Galaxy Evolution (HERITAGE) have been used to identify dusty populations of sources in the Large and Small Magellanic Clouds (LMC and SMC). We conducted the study using the HERITAGE catalogs of point sources available from the Herschel Science Center from both the Photodetector Array Camera and Spectrometer (PACS; 100 and 160{mu}m) and Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, and 500{mu}m) cameras. These catalogs are matched to each other to create a Herschel band-merged catalog and then further matched to archival Spitzer IRAC and MIPS catalogs from the Spitzer Surveying the Agents of Galaxy Evolution (SAGE) and SAGE-SMC surveys to create single mid- to far-infrared (far-IR) point source catalogs that span the wavelength range from 3.6 to 500{mu}m. There are 35,322 unique sources in the LMC and 7503 in the SMC. To be bright in the FIR, a source must be very dusty, and so the sources in the HERITAGE catalogs represent the dustiest populations of sources. The brightest HERITAGE sources are dominated by young stellar objects (YSOs), and the dimmest by background galaxies. We identify the sources most likely to be background galaxies by first considering their morphology (distant galaxies are point-like at the resolution of Herschel) and then comparing the flux distribution to that of the Herschel Astrophysical Terahertz Large Area Survey (ATLAS) survey of galaxies. We find a total of 9745 background galaxy candidates in the LMC HERITAGE images and 5111 in the SMC images, in agreement with the number predicted by extrapolating from the ATLAS flux distribution. The majority of the Magellanic Cloud-residing sources are either very young, embedded forming stars or dusty clumps of the interstellar medium. Using the presence of 24{mu}m emission as a tracer of star formation, we identify 3518 YSO candidates in the LMC and 663 in the SMC. There are far fewer far-IR bright YSOs in the SMC than the LMC due to both the SMC's smaller size and its lower dust content. The YSO candidate lists may be contaminated at low flux levels by background galaxies, and so we differentiate between sources with a high ("probable") and moderate ("possible") likelihood of being a YSO. There are 2493/425 probable YSO candidates in the LMC/SMC. Approximately 73% of the Herschel YSO candidates are newly identified in the LMC, and 35% in the SMC. We further identify a small population of dusty objects in the late stages of stellar evolution including extreme and post-asymptotic giant branch, planetary nebulae, and supernova remnants. These populations are identified by matching the HERITAGE catalogs to lists of previously identified objects in the literature. Approximately half of the LMC sources and one quarter of the SMC sources are too faint to obtain accurate ample FIR photometry and are unclassified.
- ID:
- ivo://CDS.VizieR/J/A+A/581/A30
- Title:
- Herschel maps of {rho} Oph
- Short Name:
- J/A+A/581/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of nearby star-forming regions with the Herschel Space Observatory complement our view of the protoplanetary disks in Ophiuchus with information about the outer disks. The main goal of this project is to provide new far-infrared fluxes for the known disks in the core region of Ophiuchus and to identify potential transitional disks using data from Herschel. We obtained PACS and SPIRE photometry of previously spectroscopically confirmed young stellar objects (YSO) in the region and analysed their spectral energy distributions.
