- ID:
- ivo://CDS.VizieR/J/A+A/531/A172
- Title:
- Central stars of planetary nebulae. II.
- Short Name:
- J/A+A/531/A172
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are more than 3000 confirmed and probably known Galactic planetary nebulae (PNe), but central star spectroscopic information is available for only 13% of them. We have undertaken a spectroscopic survey of the central stars in PNe to identify their spectral types. We performed spectroscopic observations at low resolution with the 2-m telescope at CASLEO, Argentina. We present the spectra of 46 central stars of PNe, most of them are OB-type and emission-line stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/618/A122
- Title:
- Cetus dSph stellar chemo-kinematics
- Short Name:
- J/A+A/618/A122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cetus is an isolated, dwarf spheroidal (dSph) galaxy at a distance of 755kpc. In order to quantify its stellar chemo-kinematical properties, we observed individual red giants branch stars in Cetus with the Very Large Telescope (VLT) FORS2 instrument, in Mask eXchange Unit (MXU) configuration. The kinematic analysis shows that Cetus is a mainly pressure-supported ({sigma}_v_=11.0^+1.6^_-1.3_km/s), dark-matter-dominated system (M_1/2_/L_V_=23.9^+9.7^_-8.9_M_{sun}_/L_{sun}_) with no significant signs of internal rotation. We find Cetus to be a metal-poor system with a significant metallicity spread (median [Fe/H]=-1.71dex, median-absolute-deviation =0.49dex), as expected for its stellar mass. We report the presence of a mild metallicity gradient compatible with those found in other dSphs of the same luminosity; we trace the presence of a stellar population gradient also in the spatial distribution of stars in different evolutionary phases in ancillary photometric data. There are tentative indications of two chemo-kinematically distinct sub-populations, with the more metal-poor stars showing a hotter kinematics than the metal-richer ones. Our results add Cetus to the growing scatter in stellar-dark matter halo properties in low-mass galactic systems. The presence of a metallicity gradient akin to those found in similar systems inhabiting different environments may hint at metallicity gradients in Local Group early-type dwarfs being driven by internal mechanisms.
343. CF-HiZELS survey
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2303
- Title:
- CF-HiZELS survey
- Short Name:
- J/MNRAS/451/2303
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from the largest contiguous narrow-band survey in the near-infrared. We have used the wide-field infrared camera/Canada-France-Hawaii Telescope and the lowOH2 filter (1.187+/-0.005{mu}m) to survey ~10deg^2^ of contiguous extragalactic sky in the SA22 field. A total of ~6000 candidate emission-line galaxies are found. We use deep ugrizJK data to obtain robust photometric redshifts. We combine our data with the High-redshift(Z) Emission Line Survey (HiZELS), explore spectroscopic surveys (VVDS, VIPERS) and obtain our own spectroscopic follow-up with KMOS, FMOS and MOSFIRE to derive large samples of high-redshift emission-line selected galaxies: 3471 H{alpha} emitters at z=0.8, 1343 [OIII] + H{beta} emitters at z=1.4 and 572 [OII] emitters at z=2.2. We probe comoving volumes of >10^6^Mpc^3^ and find significant overdensities, including an 8.5{sigma} (spectroscopically confirmed) overdensity of H{alpha} emitters at z=0.81. We derive H{alpha}, [OIII] + H{beta} and [OII] luminosity functions at z=0.8, 1.4, 2.2, respectively, and present implications for future surveys such as Euclid. Our uniquely large volumes/areas allow us to subdivide the samples in thousands of randomized combinations of areas and provide a robust empirical measurement of sample/cosmic variance. We show that surveys for star-forming/emission-line galaxies at a depth similar to ours can only overcome cosmic-variance (errors <10 percent) if they are based on volumes >5x10^5^Mpc^3^; errors on L* and {phi}* due to sample (cosmic) variance on surveys probing ~10^4^ and ~10^5^Mpc^3^ are typically very high: ~300 and ~40-60 percent, respectively.
- ID:
- ivo://CDS.VizieR/J/ApJ/455/60
- Title:
- CFRS II: 0000-00 and 1000+25 fields
- Short Name:
- J/ApJ/455/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper describes the methods used to obtain the spectroscopic data and construct redshift catalogs for the Canada-France Deep Redshift Survey (CFRS). The full data set consists of more than 1000 spectra, of objects with 17.5=<I_AB_=<22.5, obtained from deep multislit data with the MARLIN and MOS-SIS spectrographs at the Canada-France-Hawaii Telescope (CFHT). The final spectroscopic catalog contains 200 stars, 591 galaxies with secure redshifts in the range 0=<z=<1.3, six QSOs, and 146 objects with very uncertain or unknown redshifts, leading to an overall success rate of identification of 85%. In addition, 67 objects affected by observational problems have been placed in a supplemental list. We describe here the instrumental setup and the observing procedures used to gather this large data set efficiently. New optimal ways of packing spectra on the detector to increase significantly the multiplexing gain offered by multislit spectroscopy are described. Dedicated data reduction procedures have been developed under the IRAF environment to allow for fast and accurate processing. Very strict procedures have been followed to establish a reliable list of final spectroscopic measurements. Fully independent processing of the data has been carried out by three members of the team for each data set associated with a multislit mask, and final redshifts were assigned only after the careful comparison of the three independent measurements. A confidence class scheme was established. We strongly emphasize the benefits of such procedures. Finally, we present the spectroscopic data obtained for 303 objects in the 0000-00 and 1000+25 fields. The success rate in spectroscopic identification is 83% for the 0000-00 field and 84% for the 1000+25 field.
- ID:
- ivo://CDS.VizieR/J/ApJ/455/75
- Title:
- CFRS III: 1415+52 and 2215+00 fields
- Short Name:
- J/ApJ/455/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper is one of a series describing the Canada-France Redshift Survey (CFRS). It is shown how the shape of the continuum around the emission line can be used to distinguish between [O II]{lambda}3727 at z>0.76 and H{alpha} at low redshift in spectra for which only a single isolated emission line is visible. Based on this, [O II]{lambda}3727 is most likely to be the emission line in most of the single emission-line galaxies in the CFRS. The statistics of the repeated observations are analyzed to derive an empirical calibration of the reliability of the spectroscopic identifications in the CFRS in order to determine how often additional observations could lead to the identification of an initially unidentified object and to provide an estimate of the internal velocity accuracy. Finally, the results of spectroscopic observations of 413 objects in the 1415+52 and 2215+00 CFRS survey fields are presented.
- ID:
- ivo://CDS.VizieR/J/ApJ/455/88
- Title:
- CFRS IV: 0300+00 field
- Short Name:
- J/ApJ/455/88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Possible surface brightness selection effects in the redshift catalogs of the Canada-France Redshift Survey are investigated through comparisons of subsamples of the data. Our analyses demonstrate that the securing of redshifts is independent of possible biases arising from surface brightness effects and/or differing galaxy morphologies and orientations. The unusual geometry of the mask designs for our spectroscopic observations also do not produce any significant bias. There is, however, a bias at the highest and lowest redshifts, especially for absorption-line galaxies at z>1 and z<0.2, due to the adopted spectral range (4250-8500A). Apart from the latter, we conclude that our sample of identified galaxies is an unbiased subsample of the original photometric catalog and is essentially limited by I-band flux density (17.5<I_AB_<22.5). Finally, spectroscopic data for the remaining CFRS field is presented. Data for 272 objects in the 0300+0000 field are given.
- ID:
- ivo://CDS.VizieR/J/ApJ/481/49
- Title:
- CFRS XIV. Field galaxies up to z=1
- Short Name:
- J/ApJ/481/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectral properties of more than 400 Canada-France Redshift Survey (CFRS) galaxies and their changes over the redshift interval 0<=z<=1.3 are investigated. Emission-line intensities and equivalent widths for accessible lines have been measured, as well as continuum color indices based on 200{AA} wide spectral regions.
- ID:
- ivo://CDS.VizieR/J/ApJS/175/97
- Title:
- CGRaBS: survey of {gamma}-ray blazar candidates
- Short Name:
- J/ApJS/175/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe a uniform all-sky survey of bright blazars, selected primarily by their flat radio spectra, that is designed to provide a large catalog of likely {gamma}-ray active galactic nuclei (AGNs). The defined sample has 1625 targets with radio and X-ray properties similar to those of the EGRET blazars, spread uniformly across the |^b^|>10{deg} sky. We also report progress toward optical characterization of the sample; of objects with known R<23, 85% have been classified and 81% have measured redshifts. One goal of this program is to focus attention on the most interesting (e.g., high-redshift, high-luminosity, ...) sources for intensive multiwavelength study during the observations by the Large Area Telescope (LAT) on GLAST.
- ID:
- ivo://CDS.VizieR/J/ApJS/178/339
- Title:
- ChaMP extended stellar survey (ChESS)
- Short Name:
- J/ApJS/178/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS-DR6). We use morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create our catalog, the ChaMP Extended Stellar Survey (ChESS), from a sample of 2121 matched ChaMP/SDSS sources. Our cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in our final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. We present new spectral classifications and H{alpha} measurements for an additional 79 stars. The catalog is dominated by main-sequence stars; we estimate the fraction of giants in ChESS is ~10%. We identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. Future papers will present analyses of source variability and comparisons of this catalog to models of stellar activity in the Galactic disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/27
- Title:
- Chandra and AAOmega observations of Abell 2744
- Short Name:
- J/ApJ/728/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New Chandra X-ray data and extensive optical spectroscopy, obtained with AAOmega on the 3.9m Anglo-Australian Telescope, are used to study the complex merger taking place in the galaxy cluster Abell 2744. Combining our spectra with data from the literature provides a catalog of 1237 redshifts for extragalactic objects lying within 15' of the cluster center. From these, we confirm 343 cluster members projected within 3Mpc of the cluster center. Combining positions and velocities, we identify two major substructures, corresponding to the remnants of two major subclusters. The new data are consistent with a post-core-passage, major merger taking place along an axis that is tilted well out of the plane of the sky, together with an interloping minor merger. Supporting this interpretation, the new X-ray data reveal enriched, low entropy gas from the core of the approaching, major subcluster, lying ~2' north of the cluster center, and a shock front to the southeast of the previously known bright, compact core associated with the receding subcluster. The X-ray morphology of the compact core is consistent with a Bullet-like cluster viewed from within ~45{deg} of the merger axis. An X-ray peak ~3' northwest of the cluster center, with an associated cold front to the northeast and a trail of low entropy gas to the south, is interpreted as the remnant of an interloping minor merger taking place roughly in the plane of the sky. We infer approximate paths for the three merging components.
