- ID:
- ivo://CDS.VizieR/J/AJ/123/2511
- Title:
- RV photometry of Draco dwarf spheroidal galaxy
- Short Name:
- J/AJ/123/2511
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This article studies the structure of the Draco dwarf spheroidal galaxy, with an emphasis on the question of whether the spatial distribution of its stars has been affected by the tidal interaction with the Milky Way, using R- and V-band CCD photometry for 11 fields that are located in and around the Draco galaxy. 9 fields are in common with Piatek et al. (J/AJ/121/841); two additional fields, N1 and S1, are adjacent to the central C0 field studied by Piatek et al. in the north and south dire ctions, respectively, and extend beyond the tidal boundary along the minor axis. hese additional fields were imaged with the KPNO 0.9 m telescope using the 2048x2048 T2KA CCD chip. The article reports coordinates for the center, a position angle of the major axis, and the ellipticity. It also reports the results of searches for asymmetries in the structure of Draco. These results and searches for a "break" in the radial profile and for the presence of principal sequences of Draco in a color-magnitude diagram for regions more than 50' from the center yield no evidence that tidal forces from the Milky Way have affected the structure of Draco.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/527/A143
- Title:
- RX J105453.3+552102 cluster SDSS photometry
- Short Name:
- J/A+A/527/A143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The most accepted scenario for the origin of fossil groups is that they are galaxy associations in which the merging rate was fast and efficient. These systems have assembled half of their mass at early epoch of the Universe, subsequently growing by minor mergers, and therefore could contain a fossil record of the galaxy structure formation. We have started an observational project in order to characterize a large sample of fossil groups. In this paper we present the analysis of the fossil system RX J105453.3+552102.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A121
- Title:
- RXJ2314.9+2243 from radio to X-rays
- Short Name:
- J/A+A/574/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio-loud narrow-line type 1 galaxies provide us with a fresh look at the blazar phenomenon, the causes of radio loudness, and the physics of jet formation. We present a multi-wavelength study of the radio-loud narrow-line type 1 quasar RX J2314.9+2243, which exhibits some remarkable multi-wavelength properties. It is among the few radio-loud narrow-line type 1 galaxies, with a tentative {gamma}-ray detection, is luminous in the infrared, and shows an exceptionally broad and blueshifted [OIII]{lambda}5007 emission-line component. In order to understand the nature of this source, we have obtained optical, UV, X-ray, and radio observations of RX J2314.9+2243.
- ID:
- ivo://CDS.VizieR/J/ApJS/217/17
- Title:
- SAFIRES: Spitzer Archival FIR Extragalactic Survey
- Short Name:
- J/ApJS/217/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Spitzer Archival Far-InfraRed Extragalactic Survey (SAFIRES). This program produces refined mosaics and source lists for all far-infrared (FIR) extragalactic data taken during the more than six years of the cryogenic operation of the Spitzer Space Telescope. The SAFIRES products consist of FIR data in two wavelength bands (70 and 160{mu}m) across approximately 180 square degrees of sky, with source lists containing far-infrared fluxes for almost 40000 extragalactic point sources. Thus, SAFIRES provides a large, robust archival far-infrared data set suitable for many scientific goals.
- ID:
- ivo://CDS.VizieR/J/A+A/642/A153
- Title:
- SAGAN. I. New sample & multi-wavelength studies
- Short Name:
- J/A+A/642/A153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results of a project called SAGAN, which is dedicated solely to the studies of relatively rare megaparsec-scale radio galaxies in the Universe, called giant radio galaxies (GRGs). We have identified 162 new GRGs primarily from the NVSS with sizes ranging from ~0.71Mpc to 2.82Mpc in the redshift range of ~0.03-0.95, of which 23 are hosted by quasars (giant radio quasars, GRQs). As part of the project SAGAN, we have created a database of all known GRGs, the GRG catalogue, from the literature (including our new sample); it includes 820 sources. For the first time, we present the multi-wavelength properties of the largest sample of GRGs. Our results establish that the distributions of the radio spectral index and the black hole mass of GRGs do not differ from the corresponding distributions of normal-sized radio galaxies (RGs). However, GRGs have a lower Eddington ratio (ER) than RGs. Using the mid-infrared data, we classified GRGs in terms of their accretion mode: either a high-power radiatively efficient high-excitation state, or a radiatively inefficient low-excitation state. We find that GRGs in high-excitation state statistically have larger sizes, stronger radio power, jet kinetic power, and higher ER than those in low-excitation state. Our analysis reveals a strong correlation between the ER and the scaled jet kinetic power, which suggests a disc-jet coupling. Our environmental study reveals that ~10% of all GRGs may reside at the centres of galaxy clusters, in a denser galactic environment, while the majority appears to reside in a sparse environment. We find that the probability of BCG as a GRG is quite low. We present new results for GRGs that range from black hole mass to large-scale environment properties. We discuss their formation and growth scenarios, highlighting the key physical factors that cause them to reach their gigantic size.
- ID:
- ivo://CDS.VizieR/J/A+A/572/A42
- Title:
- SagDIG carbon and oxygen stars
- Short Name:
- J/A+A/572/A42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Sagittarius dwarf irregular (also known as SagDIG or UKS 1927-177) is a gas-rich, low-metallicity and star-forming galaxy, at the outskirts (D~1.1Mpc) of the Local Group. Projected relatively close to the Galactic center [(l,b)=(21.06,-16.29)] the resolved stellar populations of this galaxy reflects a strong Galactic foreground contamination, attributed to the thin and thick disk and the halo. This has so far hampered the reconstruction of its star formation and chemical enrichment history, and studies of individual stars. We have analyzed two ACS@HST data-sets (GO-9820 and GO-10472) that were collected in August 2003 and June 2005, having a ~1.85 years epoch separation. The data has allowed the derivation of the relative proper-motion for the SagDIG stellar population and reduction of the heavy foreground contamination. This provides a much clearer view of the red stellar populations (young RSG and intermediate-age AGB as well as the old RGB and AGB). The ACS/WFC data was collected in the F475W, F606W and F814W HST filters, and the published table provides a photometric calibration of the ACS/WFC filters that follows Bedin et al. (2003AJ....126..247B). This is based on the Vega spectrum and follows the recipes given by Holtzmann et al. (1995PASP..107..156H) for WFPC2, using the most updated in-flight characterization of the camera (Sirianni et al. 2005PASP..117.1049S). Besides the reported magnitudes and their relative errors, we also provide the pixel-based offset between the two F814W epochs, which is used to separate the SagDIG stellar population from the Galactic foreground (see Sec.3 of the paper for details).
- ID:
- ivo://CDS.VizieR/J/A+A/330/453
- Title:
- Sagittarius Dwarf Galaxy VI photometry
- Short Name:
- J/A+A/330/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present V,I deep CCD photometry for three fields of the dwarf galaxy in Sagittarius (Sgr), located at l=5.6{deg}, b=-14.1{deg}. One of the fields is centered on the globular cluster NGC 6715 (M54), which lies in one of the dense clumps of the Sgr galaxy. Comparing the CMD of Sgr with those of globular clusters which are believed to be kinematically associated with the dwarf galaxy (Da Costa & Armandroff, 1995AJ....109.2533D), we conclude that the stellar population of Sgr presents a spread in metallicity of -0.71<=[Fe/H]<=-1.58, and that the dominant population (=~10Gyr old) is extremely similar to the star content of the associated globular cluster Terzan 7. The estimated distance to Sgr is d=~24.55Kpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/58
- Title:
- Sagittarius stream stars with APOGEE obs.
- Short Name:
- J/ApJ/872/58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey provides precise chemical abundances of 18 chemical elements for ~176000 red giant stars distributed over much of the Milky Way Galaxy (MW), and includes observations of the core of the Sagittarius dwarf spheroidal galaxy (Sgr). The APOGEE chemical abundance patterns of Sgr have revealed that it is chemically distinct from the MW in most chemical elements. We employ a k-means clustering algorithm to six-dimensional chemical space defined by [(C+N)/Fe], [O/Fe], [Mg/Fe], [Al/Fe], [Mn/Fe], and [Ni/Fe] to identify 62 MW stars in the APOGEE sample that have Sgr-like chemical abundances. Of the 62 stars, 35 have Gaia kinematics and positions consistent with those predicted by N-body simulations of the Sgr stream, and are likely stars that have been stripped from Sgr during the last two pericenter passages (<2Gyr ago). Another 20 of the 62 stars exhibit chemical abundances indistinguishable from the Sgr stream stars, but are on highly eccentric orbits with median rapo ~25kpc. These stars are likely the "accreted" halo population thought to be the result of a separate merger with the MW 8-11 Gyr ago. We also find one hypervelocity star candidate. We conclude that Sgr was enriched to [Fe/H]~-0.2 before its most recent pericenter passage. If the "accreted halo" population is from one major accretion event, then this progenitor galaxy was enriched to at least [Fe/H]~-0.6, and had a similar star formation history to Sgr before merging.
- ID:
- ivo://CDS.VizieR/J/MNRAS/449/4010
- Title:
- SALT galaxy clusters detected by ACT
- Short Name:
- J/MNRAS/449/4010
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Southern African Large Telescope follow-up observations of seven massive clusters detected by the Atacama Cosmology Telescope (ACT) on the celestial equator using the Sunyaev-Zel'dovich (SZ) effect. We conducted multi-object spectroscopic observations with the Robert Stobie Spectrograph in order to measure galaxy redshifts in each cluster field, determine the cluster line-of-sight velocity dispersions, and infer the cluster dynamical masses. We find that the clusters, which span the redshift range 0.3<z<0.55, range in mass from (5-20)x10^14^M_{sun}_ (M_200c_). Their masses, given their SZ signals, are similar to those of Southern hemisphere ACT clusters previously observed using Gemini and the VLT. We note that the brightest cluster galaxy in one of the systems studied, ACT-CL J0320.4+0032 at z=0.38, hosts a type II quasar. Only a handful of such systems are currently known, and therefore ACT-CL J0320.4+0032 may be a rare example of a very massive halo in which quasar-mode feedback is actively taking place.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A32
- Title:
- 10 SALT spectra of HE 0435-4312
- Short Name:
- J/A+A/601/A32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The MgII emission line is visible in the optical band for intermediate redshift quasars (0.4<z<1.6) and it is thus an extremely important tool to measure the black hole mass and to understand the structure of the Broad Line Region. We aim to determine the substructure and the variability of the MgII line with the aim to identify which part of the line comes from a medium in Keplerian motion. Using the Southern African Large Telescope (SALT) with the Robert Stobie Spectrograph (RSS) we performed ten spectroscopic observations of quasar HE 0435-4312 (z=1.2231) over a period of three years (Dec 23/24, 2012 to Dec 7/8, 2015). Both the MgII line and the FeII pseudo-continuum increase with time. We clearly detect the systematic shift of the MgII line with respect to the FeII over the years, corresponding to the acceleration of 104+/-14km/s/year in the quasar rest frame. The MgII line shape is clearly non-Gaussian but single-component, and the increase in line equivalent width and line shift is not accompanied with significant evolution of the line shape. We analyse the conditions in the MgII and FeII formation region and we note that the very large difference in the covering factor and the turbulent velocity also support the conclusion that the two regions are spatially separated. The measured acceleration of the line systematic shift is too large to connect it with the orbital motion at a distance of the Broad Line Region (BLR) in this source. It may imply a precessing inner disk illuminating the BLR. Further monitoring is still needed to better constrain the variability mechanism.
