- ID:
- ivo://CDS.VizieR/J/MNRAS/465/1807
- Title:
- Deep OB star population in Carina
- Short Name:
- J/MNRAS/465/1807
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive OB stars are critical to the ecology of galaxies, and yet our knowledge of OB stars in the Milky Way, fainter than V~12, remains patchy. Data from the VST Photometric H-alpha Survey (VPHAS+) permit the construction of the first deep catalogues of blue excess-selected OB stars, without neglecting the stellar field. A total of 14900 candidates with 2MASS cross-matches are blue-selected from a 42 square-degree region in the Galactic longitude range 282{deg}<l<293{deg} Spectral energy distribution fitting is performed on these candidates' combined VPHAS+ u/g/r/i and 2MASS J/H/K magnitudes. This delivers: effective temperature constraints, statistically separating O from early-B stars; high-quality extinction parameters, A_0_ and R_V_ (random errors typically <0.1). The high confidence O-B2 candidates number 5915 and a further 5170 fit to later B spectral type. Spectroscopy of 276 of the former confirms 97% of them. The fraction of emission line stars among all candidate B stars is 7-8%. Greyer (R_V_>3.5) extinction laws are ubiquitous in the region, over the distance range 2.5-3kpc to ~10kpc. Near prominent massive clusters, R_V_ tends to rise, with particularly large and chaotic excursions to R_V_~5 seen in the Carina Nebula. The data reveal a hitherto unnoticed association of 108 O-B2 stars around the O5If+ star LSS 2063 (l=289.77{deg}, b=-1.22{deg}). Treating the OB star scale-height as a constant within the thin disk, we find an orderly mean relation between extinction (A_0_) and distance in the Galactic longitude range, 287.6{deg}<l< 293.5{deg}, and infer the subtle onset of thin-disk warping. A halo around NGC 3603, roughly a degree in diameter, of ~500 O-B2 stars with 4<A_0_(mag)<7 is noted.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/891/81
- Title:
- Deep optical and infrared photometry of Sh2-305
- Short Name:
- J/ApJ/891/81
- Date:
- 17 Jan 2022 00:38:10
- Publisher:
- CDS
- Description:
- Using our deep optical and near-infrared photometry along with multiwavelength archival data, we here present a detailed study of the Galactic HII region Sh 2-305 to understand the star/star-cluster formation. On the basis of excess infrared emission, we have identified 116 young stellar objects (YSOs) within a field of view of ~18.5'x18.5' around Sh 2-305. The average age, mass, and extinction (AV) for this sample of YSOs are 1.8Myr, 2.9M_{sun}_, and 7.1mag, respectively. The density distribution of stellar sources along with minimal spanning tree calculations on the location of YSOs reveals at least three stellar subclusterings in Sh 2-305. One cluster is seen toward the center (i.e., Mayer 3), while the other two are distributed toward the north and south directions. Two massive O-type stars (VM2 and VM4; ages ~5Myr) are located at the center of the Sh 2-305 HII region. The analysis of the infrared and radio maps traces the photon-dominant regions (PDRs) in Sh 2-305. The association of the younger generation of stars with the PDRs is also investigated in Sh2-305. This result suggests that these two massive stars might have influenced the star formation history in Sh 2-305. This argument is also supported by the calculation of various pressures driven by massive stars, the slope of the mass function/K-band luminosity function, star formation efficiency, fraction of Class I sources, and mass of the dense gas toward the subclusterings in Sh 2-305.
- ID:
- ivo://CDS.VizieR/J/ApJ/518/69
- Title:
- Deep Optical Catalog of galaxy systems
- Short Name:
- J/ApJ/518/69
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We assemble and observe a sample of poor galaxy systems that is suitable for testing N-body simulations of hierarchical clustering and other dynamical halo models. We (1) determine the parameters of the density profile {Rho}(r) and the velocity dispersion profile {sigma}_p_(R), (2) separate emission-line galaxies from absorption-line galaxies, examining the model parameters, {beta}, and as a function of spectroscopic type, and (3) for the best-behaved subsample, constrain the velocity anisotropy parameter, {beta}, which determines the shapes of the galaxy orbits. Our sample consists of 20 systems, 12 of which have extended X-ray emission in the ROSAT All-Sky Survey. We measure the 877 optical spectra of galaxies brighter than m_R_~15.4 within 1.5h^-1^Mpc of the system centers (we take H_0_=100h*km/s/Mpc). Thus, we sample the system membership to a radius typically three times larger than other recent optical group surveys. The average system population is 30 galaxies, and the average line-of-sight velocity dispersion is ~300km/s. The Navarro, Frenk, & White universal profile and the Hernquist model both provide good descriptions of the spatial data. In most cases an isothermal sphere is ruled out. Systems with declining {sigma}_p_(R) are well-matched by theoretical profiles in which the star-forming galaxies have predominantly radial orbits ({beta}>0); many of these galaxies are probably falling in for the first time. There is significant evidence for spatial segregation of the spectroscopic classes regardless of {sigma}_p_(R).
- ID:
- ivo://CDS.VizieR/J/ApJS/184/152
- Title:
- Deep optical photometry in M31
- Short Name:
- J/ApJS/184/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Advanced Camera for Surveys on the Hubble Space Telescope, we have obtained deep optical images reaching well below the oldest main-sequence turnoff in six fields of the Andromeda Galaxy. The fields fall at four positions on the southeast minor axis, one position in the giant stellar stream, and one position on the northeast major axis. These data were obtained as part of three large observing programs designed to probe the star formation history of the stellar population in various structures of the galaxy. In this paper, we present the images, catalogs, and artificial star tests for these observing programs as a supplement to the analyses published previously. These high-level science products are also archived at the Multimission Archive at the Space Telescope Science Institute.
- ID:
- ivo://CDS.VizieR/J/A+AS/82/71
- Title:
- Deep photometry of NGC 5694 and Terzan 8
- Short Name:
- J/A+AS/82/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present deep CCD photometries for the little known metal-poor clusters NGC 5694 and Terzan 8 down to V~24. NGC 5694 has a blue horizontal branch, a very high radial velocity, a metallicity of [Fe/H]=-1.65+/-0.06, a reddening of E(B-V)=0.10+/-0.03, and an apparent distance modulus of (m-M)_v_=17.82+/-0.15. It is located at 26.0+/-1.8kpc from the galactic center. The helium content derived from the ratio between the number of stars on the horizontal branch and the giant and asymptotic giant branches is consistent with that obtained for other clusters. Terzan 8 is a metal-poor ([Fe/H]=-1.81+/-0.10) moderately reddened (E(B-V)=0.20+/-0.05) cluster with a blue horizontal branch and apparent distance modulus of (m-M)_v_=17.25+/-0.15. It is located at 13.8+/-2.0 kpc from the galactic center. The c-m diagram and the luminosity function of NGC 5694 and Terzan 8 are similar to the M92 ones. NGC 5694 and Terzan 8 have ages close to that of the "classical" globular cluster M92.
- ID:
- ivo://CDS.VizieR/J/MNRAS/413/1024
- Title:
- Deep proper-motion survey of Blanco 1
- Short Name:
- J/MNRAS/413/1024
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide two comprehensive catalogues of positions and proper motions in the area of open cluster Blanco 1. The main catalogue, CtlgM (table1), contains 6271 objects down to V~18.5 and covers a circular ~11deg^2^ area. The accuracy of CtlgM proper motions, at about 0.3-0.5mas/yr for well-measured stars, permits an excellent segregation between the cluster and field stars.
- ID:
- ivo://CDS.VizieR/III/268
- Title:
- DEEP2 Redshift Survey, Data Release 4
- Short Name:
- III/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes a new catalog that supplements the existing DEEP2 Galaxy Redshift Survey photometric and spectroscopic catalogs with ugriz photometry from two other surveys: the Canada-France-Hawaii Legacy Survey (CFHTLS) and the Sloan Digital Sky Survey (SDSS). Each catalog is cross-matched by position on the sky in order to assign ugriz photometry to objects in the DEEP2 catalogs. We have recalibrated the CFHTLS photometry where it overlaps DEEP2 in order to provide a more uniform data set. We have also used this improved photometry to predict DEEP2 BRI photometry in regions where only poorer measurements were available previously. In addition, we have included improved astrometry tied to SDSS rather than USNO-A2.0 for all DEEP2 objects. In total this catalog contains ~27, 000 objects with full ugriz photometry as well as robust spectroscopic redshift measurements, 64% of which have r > 23. By combining the secure and accurate redshifts of the DEEP2 Galaxy Redshift Survey with ugriz photometry, we have created a catalog that can be used as an excellent testbed for future photo-z studies, including tests of algorithms for surveys such as LSST and DES.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A81
- Title:
- Deep SDSS Optical Spectroscopy. II.
- Short Name:
- J/A+A/577/A81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze a sample of 3942 low-resolution (R~2000) optical spectra from the Sloan Digital Sky Survey (SDSS), focusing on stars with effective temperatures 5800<Teff<6300K, and distances from the Milky Way plane in excess of 5kpc, and determine their abundances of Fe, Ca, and Mg. This work follows the same methodology as in the previous paper in this series, deriving atmospheric parameters by chi^2^ minimization, but we now obtain the abundances of individual elements by fitting their associated spectral lines. Distances are calculated from absolute magnitudes obtained by a statistical comparison of our stellar parameters with stellar-evolution models. The observations reveal a decrease in the abundances of iron, calcium and magnesium at large distances from the Galactic center. The median abundances for the halo stars analyzed are fairly constant up to a Galactocentric distance r~20kpc, rapidly decrease between r~20 and r~40kpc, and flatten out to significantly lower values at larger distances, consistent with previous studies. In addition, we examine the Ca/Fe and Mg/Fe ratios as a function of Fe/H and Galactocentric distance. Our results show that the most distant parts of the halo show a steeper variation of the Ca/Fe and Mg/Fe with iron. We found that at the range -1.6<[Fe/H]<-0.4 the Ca/Fe ratio decreases with distance, in agreement with earlier results based on local stars. However, the opposite trend is apparent for Mg/Fe. Our conclusion that the outer regions of the halo are more metal-poor than the inner regions, based on in-situ observations of distant stars, is in concert with recent results based on inferences from the kinematics of more local stars, and with predictions of recent galaxy formation simulations for galaxies similar to the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/115
- Title:
- Deep spectroscopy in the GOODS fields
- Short Name:
- J/ApJ/741/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new measures of the evolving scaling relations between stellar mass, luminosity and rotational velocity for a morphologically inclusive sample of 129 disk-like galaxies with z_AB_<22.5 in the redshift range 0.2<z<1.3, based on spectra from DEep Imaging Multi-Object Spectrograph on the Keck II telescope, multi-color Hubble Space Telescope (HST) Advanced Camera for Surveys photometry, and ground-based Ks-band imaging. A unique feature of our survey is the extended spectroscopic integration times, leading to significant improvements in determining characteristic rotational velocities for each galaxy. Rotation curves are reliably traced to the radius where they begin to flatten for ~90% of our sample, and we model the HST-resolved bulge and disk components in order to accurately de-project our measured velocities, accounting for seeing and dispersion. We demonstrate the merit of these advances by recovering an intrinsic scatter on the stellar mass Tully-Fisher relation a factor of two to three less than in previous studies at intermediate redshift and comparable to that of locally determined relations. With our increased precision, we find that the relation is well established by <z>~1, with no significant evolution to <z>~0.3, {Delta}M_*_~0.04+/-0.07dex. A clearer trend of evolution is seen in the B-band Tully-Fisher relation corresponding to a decline in luminosity of {Delta}M_B_~0.85+/-0.28 magnitudes at fixed velocity over the same redshift range, reflecting the changes in star formation over this period. As an illustration of the opportunities possible when gas masses are available for a sample such as ours, we show how our dynamical and stellar mass data can be used to evaluate the likely contributions of baryons and dark matter to the assembly history of spiral galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/458/1590
- Title:
- Deep spectroscopy of Abell 85
- Short Name:
- J/MNRAS/458/1590
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new deep spectroscopic catalogue for Abell 85, within 3.0x2.6Mpc^2^ and down to M_r_~M_r_^*^+6. Using the Visible Multi-Object Spectrograph at the Very Large Telescope and the AutoFiber 2 at the William Herschel Telescope, we obtained almost 1430 new redshifts for galaxies with m_r_<=21mag and <{mu}_e,r_><=24mag/arcsec^2^. These redshifts, together with Sloan Digital Sky Survey Data Release 6 and NASA/IPAC Extragaalctic Database spectroscopic information, result in 460 confirmed cluster members. This data set allows the study of the luminosity function (LF) of the cluster galaxies covering three orders of magnitudes in luminosities. The total and radial LFs are best modelled by a double Schechter function. The normalized LFs show that their bright (M_r_<=-21.5) and faint (M_r_>=-18.0) ends are independent of clustercentric distance and similar to the field LFs unlike the intermediate luminosity range (-21.5<=M_r_<=-18.0). Similar results are found for the LFs of the dominant types of galaxies: red, passive, virialized and early-infall members. On the contrary, the LFs of blue, star forming, non-virialized and recent-infall galaxies are well described by a single Schechter function. These populations contribute to a small fraction of the galaxy density in the innermost cluster region. However, in the outskirts of the cluster, they have similar densities to red, passive, virialized and early-infall members at the LF faint end. These results confirm a clear dependence of the colour and star formation of Abell 85 members in the cluster centric distance.