- ID:
- ivo://CDS.VizieR/J/ApJS/162/1
- Title:
- MUSYC: optical source catalog
- Short Name:
- J/ApJS/162/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present UBVRIz' optical images taken with MOSAIC on the CTIO 4m telescope of the 0.32{deg}^2^ Extended Hubble Deep Field-South. This is one of four fields comprising the MUSYC survey, which is optimized for the study of galaxies at z=3, active galactic nucleus (AGN) demographics, and Galactic structure. Our methods used for astrometric calibration, weighted image combination, and photometric calibration in AB magnitudes are described. We calculate corrected aperture photometry and its uncertainties and find through tests that these provide a significant improvement upon standard techniques. Our photometric catalog of 62,968 objects is complete to a total magnitude of R_AB_=25, with R-band counts consistent with results from the literature.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/489/533
- Title:
- M83 volume densities of giant molecular clouds
- Short Name:
- J/A+A/489/533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using observed GALEX far-ultraviolet (FUV) fluxes and VLA images of the 21-cm HIcolumn densities, along with estimates of the local dust abundances, we measure the volume densities of a sample of actively star-forming giant molecular clouds (GMCs) in the nearby spiral galaxy M83 on a typical resolution scale of 170 pc. Our approach is based on an equilibrium model for the cycle of molecular hydrogen formation on dust grains and photodissociation under the influence of the FUV radiation on the cloud surfaces of GMCs. We find a range of total volume densities on the surface of GMCs in M83, namely 0.1-400cm^-3^ inside R_25_, 0.5-50cm^-3^ outside R_25_. Our data include a number of GMCs in the HI-ring surrounding this galaxy. Finally, we discuss the effects of observational selection, which may bias our results.
- ID:
- ivo://CDS.VizieR/J/A+A/571/L4
- Title:
- MWC 349A Halpha lines with 14<n<24 spectra
- Short Name:
- J/A+A/571/L4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UC-HII region of MWC 349A is the prototype of an ionized wind driven by a massive star surrounded by a disk. Recent high angular resolution observations of the millimeter recombination lines have shown that the disk rotates with a Keplerian law in its outer parts. However, the kinematics of innermost regions in the UC-HII region of MWC 349A is still unknown, in particular the radius where the wind is launched from the disk. We performed hydrogen recombination line observations with the Heterodyne Instrument for the Far Infrared (HIFI) onboard the Herschel Space Observatory to study the kinematics of its innermost regions by studying their spectral features. In addition to the two laser peaks, we report the first detection of two new components that are blueshifted with respect to the laser peaks for all the recombination lines with principal quantum number n<22. These new spectral features originate from the region where the wind is ejected from the disk. We used our 3D non-LTE radiative transfer model for recombination lines (MORELI) to show that these features are consistent with the wind being ejected at a radius of about 24 AU from the star, which supports magnetohydrodynamic wind models.
2394. M33 WR and Of-type Stars
- ID:
- ivo://CDS.VizieR/J/ApJ/789/10
- Title:
- M33 WR and Of-type Stars
- Short Name:
- J/ApJ/789/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the "extra" WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ~100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.
2395. M83 X-ray sources
- ID:
- ivo://CDS.VizieR/J/A+A/410/53
- Title:
- M83 X-ray sources
- Short Name:
- J/A+A/410/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have identified 127 discrete sources in a Chandra ACIS observation of M 83, with a detection limit of ~3x10^36^erg/s in the 0.3-8.0keV band.
- ID:
- ivo://CDS.VizieR/J/MNRAS/414/1329
- Title:
- M82 X-ray sources long-term variability
- Short Name:
- J/MNRAS/414/1329
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the long-term variability exhibited by the X-ray point sources in the starburst galaxy M82. By combining nine Chandra observations taken between 1999 and 2007, we detect 58 X-ray point sources within the D_25_ isophote of M82 down to a luminosity of ~10^37^erg/s. Of these 58 sources, we identify three supernova remnant candidates and one supersoft source. 26 sources in M82 exhibit long-term (i.e. days to years) flux variability and three show long-term spectral variability. Furthermore, we classify 26 sources as variables and 10 as persistent sources. Among the total 26 variables, 17 varied by a flux ratio of >3 and six are transient candidates. By comparing with other nearby galaxies, M82 shows extremely strong long-term X-ray variability that 47 per cent of the X-ray sources are variables with a flux ratio of >3. The strong X-ray variability of M82 suggests that the population is dominated by X-ray binaries.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/525
- Title:
- M83 young star cluster light profiles
- Short Name:
- J/MNRAS/452/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We measure the radii and two-dimensional light profiles of a large sample of young, massive star clusters in M83 using archival HST/Wide Field Camera 3 (WFC3) imaging of seven adjacent fields. We use galfit to fit the two-dimensional light profiles of the clusters, from which we find effective (half-light) radii, core radii, and slopes of the power-law (EFF) profile ({eta}). We find lognormal distributions of effective radius and core radius, with medians of ~2.5 and ~1.3pc, respectively. Our results provide strong evidence for a characteristic size of young, massive clusters. The average effective radius and core radius increase somewhat with cluster age. Little to no change in effective radius is observed with increasing galactocentric distance, except perhaps for clusters younger than 100Myr. We find a shallow correlation between effective radius and mass for the full cluster sample, but a stronger correlation is present for clusters 200-300Myr in age. Finally, the majority of the clusters are best fit by an EFF model with index {eta} <~3.0. There is no strong evidence for change in {eta} with cluster age, mass, or galactocentric distance. Our results suggest that clusters emerge from early evolution with similar radii and are not strongly affected by the tidal field of M83. Mass-loss due to stellar evolution and/or giant molecular cloud interactions appear to dominate cluster expansion in the age range we study.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/7
- Title:
- Narrowband Ca photometry for dwarf spheroidal galaxies
- Short Name:
- J/ApJS/247/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A few dozen dwarf satellite galaxies of the Milky Way have been discovered, which are often viewed as the remaining building blocks of our Galaxy. The follow-up spectroscopy showed that dwarf galaxies have a sizeable spread in their metallicities. Several scenarios were suggested to explain the metallicity spread, which can be tested by the structural patterns of stellar subpopulations with distinct metallicities. However, such chemical plus structural examination, which we refer to as "chemostructural study", is hindered by the lack of stars with spectroscopic metallicity. Here we propose the Ca-by photometry as an alternative way to secure metallicities for a 2-3 orders of magnitude larger stellar sample than the spectroscopic sample and thus enable us to perform a chemostructural study on dwarf galaxies. In particular, we use the hk index [=(Ca-b)-(b-y)], whose validity as a photometric metallicity indicator (and crass insensitivity to age) for red-giant-branch stars was upheld via Galactic globular clusters, and observe three dwarf spheroidal galaxies-Draco, Sextans, and Canes Venatici I (CVnI)-with Subaru/Suprime-Cam. We find that in all the galaxies the metal-rich stellar populations are more centrally concentrated than the metal-poor counterparts, suggesting that the central regions of the galaxies underwent extended star formation. Such a negative radial metallicity gradient for Sextans and CVnI opposes the traditional spectroscopic results. We also find that their metallicity distribution functions (MDFs) can be characterized by a unimodal, skewed Gaussian shape with a metal-rich peak and a metal-poor tail.
- ID:
- ivo://CDS.VizieR/J/A+A/456/953
- Title:
- Narrow-band imaging of 6 Seyfert-2 galaxies
- Short Name:
- J/A+A/456/953
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding starbursts. Recently, we have shown that long-slit spectroscopy provides a valuable alternative approach to probe the size in terms of AGN photoionisation. Moreover, several parameters of the NLR can be directly accessed. We here apply the same methods developed and described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation of the NLR and thus, its "real" size using diagnostic line-ratio diagrams. We derive physical properties of the NLR such as reddening, ionisation parameter, electron density, and velocity as a function of distance from the nucleus. For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius. Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample. We discuss our findings in detail for each object.
- ID:
- ivo://CDS.VizieR/J/A+A/459/55
- Title:
- Narrow-band imaging of 5 Seyfert-1 galaxies
- Short Name:
- J/A+A/459/55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spatially resolved emission-line spectroscopy is a powerful tool to determine the physical conditions in the narrow-line region (NLR) of active galactic nuclei (AGNs). We recently used optical long-slit spectroscopy to study the NLRs of a sample of six Seyfert-2 galaxies. We have shown that such an approach, in comparison to the commonly used [OIII] narrow-band imaging alone, allows us to probe the size of the NLR in terms of AGN photoionisation. Moreover, several physical parameters of the NLR can be directly accessed. We here apply the same methods to study the NLR of six Seyfert-1 galaxies and compare our results to those of Seyfert-2 galaxies. We employ diagnostically valuable emission-line ratios to determine the physical properties of the NLR, including the core values and radial dependencies of density, ionisation parameter, and reddening. Tracking the radial change of emission-line ratios in diagnostic diagrams allows us to measure the transition between AGN-like and HII-like line excitation, and thus we are able to measure the size of the NLR. In the diagnostic diagrams, we find a transition between line ratios falling in the AGN regime and those typical for HII regions in two Seyfert-1 galaxies, thus determining the size of the NLR. The central electron temperature and ionisation parameter are in general higher in type-1 Seyferts than in type 2s. In almost all cases, both electron density and ionisation parameter decrease with radius. In general, the decrease is faster in Seyfert-1 galaxies than in type 2s. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We give estimates of the black hole masses. We discuss our findings in detail for each object.
