- ID:
- ivo://CDS.VizieR/J/A+AS/139/483
- Title:
- Early-type gal. kinematics in compact groups
- Short Name:
- J/A+AS/139/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of stellar kinematics for seven early-type galaxies in HCG 67, HCG 74, and HCG 79. These data are aimed at studying the relation between the environment and the dynamics, structure and stellar content of early-type galaxies. In the present three groups, the kinematic features we observed cannot be associated unambiguously to physical interactions. Visible morphological peculiarities do not appear correlated with kinematical perturbations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2220
- Title:
- Early-type Sco-Cen members with literature RVs
- Short Name:
- J/MNRAS/453/2220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the serendipitous discovery of several young mid-M stars found during a search for new members of the 30-40Myr-old Octans Association. Only one of the stars may be considered a possible Octans(-Near) member. However, two stars have proper motions, kinematic distances, radial velocities, photometry and LII {lambda}6708 measurements consistent with membership in the 8-10Myr-old TW Hydrae Association. Another may be an outlying member of TW Hydrae but has a velocity similar to that predicted by membership in Octans. We also identify two new lithium-rich members of the neighbouring Scorpius-Centaurus OB Association (Sco-Cen). Both exhibit large 12 and 22{mu}m excesses and strong, variable H{alpha} emission which we attribute to accretion from circumstellar discs. Such stars are thought to be incredibly rare at the ~16Myr median age of Sco-Cen and they join only one other confirmed M-type and three higher mass accretors outside of Upper Scorpius. The serendipitous discovery of two accreting stars hosting large quantities of circumstellar material may be indicative of a sizeable age spread in Sco-Cen, or further evidence that disc dispersal and planet formation time-scales are longer around lower mass stars. To aid future studies of Sco-Cen, we also provide a newly compiled catalogue of 305 early-type Hipparcos members with spectroscopic radial velocities sourced from the literature.
- ID:
- ivo://CDS.VizieR/J/A+A/342/671
- Title:
- Early-type spiral galaxies kinematics
- Short Name:
- J/A+A/342/671
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the stellar and ionized-gas velocity curves and velocity-dispersion profiles along the major axis for six early-type spiral galaxies. Two of these galaxies, namely NGC 2179 and NGC 2775, are particularly suited for the study of dark matter halos. Using their luminosity profiles and modeling their stellar and gaseous kinematics, we derive the mass contributions of the luminous and the dark matter to the total potential. In NGC 2179 we find that the data (measured out to about the optical radius R_opt_) unambiguously require the presence of a massive dark halo. For the brighter and bigger object NGC 2775, we can rule out a significant halo contribution at radii R<~0.6R_opt_. Although preliminary, these results agree with the familiar mass distribution trend known for late-type spirals of comparable mass.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/4346
- Title:
- Early-type stars in SMC and LMC
- Short Name:
- J/MNRAS/451/4346
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We employ CaII K and NaI D interstellar absorption-line spectroscopy of early-type stars in the Large and Small Magellanic Clouds (LMC, SMC) to investigate the large- and small-scale structure in foreground intermediate- and high-velocity clouds (I/HVCs). Data include FLAMES-GIRAFFE CaII K observations of 403 stars in four open clusters, plus FEROS or UVES spectra of 156 stars in the LMC and SMC. The FLAMES observations are amongst the most extensive probes to date of CaII structures on ~20-arcsec scales in Magellanic I/HVCs. From the FLAMES data within a 0.5{deg} field of view, the CaII K equivalent width in the I/HVC components towards three clusters varies by factors of >=10. There are no detections of molecular gas in absorption at intermediate or high velocities, although molecular absorption is present at LMC and Galactic velocities towards some sightlines. The FEROS/UVES data show CaII K I/HVC absorption in ~60 per cent of sightlines. The range in the CaII/NaI ratio in I/HVCs is from -0.45 to +1.5dex, similar to previous measurements for I/HVCs. In 10 sightlines we find CaII/Oi ratios in I/HVC gas ranging from 0.2 to 1.5dex below the solar value, indicating either dust or ionization effects. In nine sightlines I/HVC gas is detected in both Hi and CaII at similar velocities, implying that the two elements form part of the same structure.
- ID:
- ivo://CDS.VizieR/J/ApJ/771/110
- Title:
- Early-type stars in Taurus-Auriga
- Short Name:
- J/ApJ/771/110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the results of a search for early-type stars associated with the Taurus-Auriga molecular cloud complex, a diffuse nearby star-forming region noted as lacking young stars of intermediate and high mass. We investigate several sets of possible O, B, and early A spectral class members. The first is a group of stars for which mid-infrared images show bright nebulae, all of which can be associated with stars of spectral-type B. The second group consists of early-type stars compiled from (1) literature listings in SIMBAD, (2) B stars with infrared excesses selected from the Spitzer Space Telescope survey of the Taurus cloud (Rebull et al. 2010, J/ApJS/186/259), (3) magnitude- and color-selected point sources from the Two Micron All Sky Survey (Skrutskie et al. 2006, VII/233), and (4) spectroscopically identified early-type stars from the Sloan Digital Sky Survey coverage of the Taurus region (Finkbeiner et al. 2004AJ....128.2577F; Knapp et al. 2007AAS...211.2907K). We evaluated stars for membership in the Taurus-Auriga star formation region based on criteria involving: spectroscopic and parallactic distances, proper motions and radial velocities, and infrared excesses or line emission indicative of stellar youth. For selected objects, we also model the scattered and emitted radiation from reflection nebulosity and compare the results with the observed spectral energy distributions to further test the plausibility of physical association of the B stars with the Taurus cloud. This investigation newly identifies as probable Taurus members three B-type stars: HR 1445 (HD 28929), {tau} Tau (HD 29763), 72 Tau (HD 28149), and two A-type stars: HD 31305 and HD 26212, thus doubling the number of stars A5 or earlier associated with the Taurus clouds. Several additional early-type sources including HD 29659 and HD 283815 meet some, but not all, of the membership criteria and therefore are plausible, though not secure, members.
- ID:
- ivo://CDS.VizieR/J/ApJ/643/1011
- Title:
- Early-type stars in the center of the Galaxy
- Short Name:
- J/ApJ/643/1011
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the definite spectroscopic identification of ~40 OB supergiants, giants, and main-sequence stars in the central parsec of the Galaxy. Detection of their absorption lines has become possible with the high spatial and spectral resolution and sensitivity of the adaptive optics integral field spectrometer SPIFFI/SINFONI on the ESO VLT. Several of these OB stars appear to be helium- and nitrogen-rich.
- ID:
- ivo://CDS.VizieR/J/A+A/373/608
- Title:
- Early-type stars towards the Galactic Center. II.
- Short Name:
- J/A+A/373/608
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are searching for early-type stars towards the Galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. Photographic photometry from the UK Schmidt Telescope has been used to identify the bluest candidates in nineteen Schmidt fields (centred close to the Galactic centre). We have previously obtained FLAIR low dispersion spectroscopy for three of these fields to estimate spectral types and here we present spectroscopy for an additional seven fields. Combining the results for all ten fields, 56 stars were initially classified as early-B type. Estimates of the equivalent widths of their Balmer and He I lines have been used to estimate atmospheric parameters and 32 targets have effective temperatures greater than or equal to 17000K (corresponding to a spectral type of B3 or earlier). The spectra of seven of these targets also have absorption lines due to O II and Si III and can be reliably classified as early-B type. Additionally 78 stars have estimated effective temperatures between 11000 and 16000K with a further 50 objects identified as late-B (or early-A) type. All but two of the early B-type candidates have magnitudes in the range 12.0<=V<=16.0, and our best estimates of their distance suggest that they could be close to (i.e. R_g_<3kpc), or even beyond the Galactic centre.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/231
- Title:
- Early-type stars towards the Galactic Centre
- Short Name:
- J/A+AS/139/231
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have begun a search for early-type stars towards the galactic centre which are potentially young objects situated within the inner few kiloparsecs of the disk. U and V (or I) band photographic photometry from the UK Schmidt Telescope has been obtained to identify the bluest candidates in nineteen Schmidt fields (centred close to the galactic centre). We have spectroscopically observed these targets for three fields with the FLAIR multi-fibre system to determine their spectral types. In particular, ten early B-type stars have been identified and equivalent width measurements of their Balmer and HeI lines have been used to estimate atmospheric parameters. These early-type objects have magnitudes in the range 11.5=<V<=16.0, and our best estimates of their distance (given probable highly variable reddening in this direction together with errors in the plate photometry) suggest that some of them originated close to (i.e R_g_<3kpc), or even beyond the galactic centre. Future high-resolution spectroscopy of these stars will provide reliable atmospheric parameters and element abundances, in order to map the current chemical composition of the inner galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/53
- Title:
- Early X-ray flares in GRBs
- Short Name:
- J/ApJ/852/53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the early X-ray flares in the GRB "flare-plateau-afterglow" (FPA) phase observed by Swift-XRT. The FPA occurs only in one of the seven GRB subclasses: the binary-driven hypernovae (BdHNe). This subclass consists of long GRBs with a carbon-oxygen core and a neutron star (NS) binary companion as progenitors. The hypercritical accretion of the supernova (SN) ejecta onto the NS can lead to the gravitational collapse of the NS into a black hole. Consequently, one can observe a GRB emission with isotropic energy E_iso_>~10^52^erg, as well as the associated GeV emission and the FPA phase. Previous work had shown that gamma-ray spikes in the prompt emission occur at ~10^15^-10^17^cm with Lorentz Gamma factors {Gamma}~10^2^-10^3^. Using a novel data analysis, we show that the time of occurrence, duration, luminosity, and total energy of the X-ray flares correlate with Eiso. A crucial feature is the observation of thermal emission in the X-ray flares that we show occurs at radii ~10^12^cm with {Gamma}<~4. These model-independent observations cannot be explained by the "fireball" model, which postulates synchrotron and inverse-Compton radiation from a single ultrarelativistic jetted emission extending from the prompt to the late afterglow and GeV emission phases. We show that in BdHNe a collision between the GRB and the SN ejecta occurs at ~10^10^cm, reaching transparency at ~10^12^cm with {Gamma}<~4. The agreement between the thermal emission observations and these theoretically derived values validates our model and opens the possibility of testing each BdHN episode with the corresponding Lorentz Gamma factor.
- ID:
- ivo://CDS.VizieR/J/A+A/440/373
- Title:
- Earthbound interplanetary shocks
- Short Name:
- J/A+A/440/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table contains space weather data based on 360 interplanetary shocks (forward and reverse) observed by ACE during the 80 month time period from January 1998 to August 2004. Data from ACE, WIND, LASCO and GOES are included, as well as Dst, Ap, SC information and SEC prediction times.