- ID:
- ivo://CDS.VizieR/J/AJ/134/1877
- Title:
- Spectropolarimetry of R CrB in 1998-2003
- Short Name:
- J/AJ/134/1877
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extended optical spectropolarimetry of R CrB from 1998 January to 2003 September. The polarization was almost constant in the phase of maximum brightness, being consistent with past observations. We detected, however, temporary changes of the polarization (~0.5%) in 2001 March and August, which were the first detections of large polarization variability in R CrB near maximum brightness. The amplitude and the position angle of the "transient polarization" were almost constant with wavelength in both events. There was a difference of about 20{deg} in the position angle between the two events. Each event could be explained by light scattering due to a short-lived dust puff occasionally ejected off the line of sight.
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- ID:
- ivo://CDS.VizieR/J/AJ/147/16
- Title:
- Spectroscocpy of planetary nebulae in M31
- Short Name:
- J/AJ/147/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have developed a method to identify planetary nebula (PN) candidates in imaging data of the Sloan Digital Sky Survey (SDSS). This method exploits the SDSS's five-band sampling of emission lines in PN spectra, which results in a color signature distinct from that of other sources. Selection criteria based on this signature can be applied to nearby galaxies in which PNe appear as point sources. We applied these criteria to the whole area of M31 as scanned by the SDSS, selecting 167 PN candidates that are located in the outer regions of M31. The spectra of 80 selected candidates were then observed with the 2.2m telescope at Calar Alto Observatory. These observations and cross-checks with literature data show that our method has a selection rate efficiency of about 90%, but the efficiency is different for the different groups of PN candidates. In the outer regions of M31, PNe trace different well-known morphological features like the Northern Spur, the NGC 205 Loop, the G1 Clump, etc. In general, the distribution of PNe in the outer region 8<R<20kpc along the minor axis shows the "extended disk"-a rotationally supported low surface brightness structure with an exponential scale length of 3.21+/-0.14kpc and a total mass of ~10^10^M_{sun}_, which is equivalent to the mass of M33. We report the discovery of three PN candidates with projected locations in the center of Andromeda NE, a very low surface brightness giant stellar structure in the outer halo of M31. Two of the PNe were spectroscopically confirmed as genuine PNe. These two PNe are located at projected distances along the major axis of ~48Kpc and ~41Kpc from the center of M31 and are the most distant PNe in M31 found up to now. With the new PN data at hand we see the obvious kinematic connection between the continuation of the Giant Stream and the Northern Spur. We suggest that 20%-30% of the stars in the Northern Spur area may belong to the Giant Stream. In our data we also see a possible kinematic connection between the Giant Stream and PNe in Andromeda NE, suggesting that Andromeda NE could be the core or remnant of the Giant Stream. Using PN data we estimate the total mass of the Giant Stream progenitor to be {approx}10^9^M_{sun}_. About 90% of its stars appear to have been lost during the interaction with M31.
- ID:
- ivo://CDS.VizieR/J/ApJ/839/42
- Title:
- Spectrosc. of the circumstellar gas of WD1145+017
- Short Name:
- J/ApJ/839/42
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the recent discovery of transiting planetary material around WD1145+017, a critical target has been identified that links the evolution of planetary systems with debris disks and their accretion onto the star. We present a series of observations, five epochs over a year, taken with Keck and the VLT, which for the first time show variability of circumstellar absorption in the gas disk surrounding WD1145+017 on timescales of minutes to months. Circumstellar absorption is measured in more than 250 lines of 14 ions among 10 different elements associated with planetary composition, e.g., O, Mg, Ca, Ti, Cr, Mn, Fe, and Ni. Broad circumstellar gas absorption with a velocity spread of 225km/s is detected, but over the course of a year blueshifted absorption disappears, while redshifted absorption systematically increases. A correlation of equivalent width and oscillator strength indicates that the gas is not highly optically thick (median {tau}~2). We discuss simple models of an eccentric disk coupled with magnetospheric accretion to explain the basic observed characteristics of these high-resolution and high signal- to-noise observations. Variability is detected on timescales of minutes in the two most recent observations, showing a loss of redshifted absorption for tens of minutes, coincident with major transit events and consistent with gas hidden behind opaque transiting material. This system currently presents a unique opportunity to learn how the gas causing the spectroscopic, circumstellar absorption is associated with the ongoing accretion evidenced by photospheric contamination, as well as the transiting planetary material detected in photometric observations.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/3
- Title:
- Spectroscopic accuracy for B-like ions with Z=24-30
- Short Name:
- J/ApJS/239/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report calculations of spectroscopic accuracy for 513 states in the B-like ions with Z=24-30. The energy levels and transition rates are calculated using the second-order many-body perturbation theory, while multiconfiguration Dirac-Hartree-Fock calculations are performed to support the former results. The present two sets of results agree excellently with each other, and can be used as benchmarks in the future. The electron-impact excitation (EIE) collision strengths are calculated based on independent processes and isolated resonances approximation using the distorted wave method. Based on the present atomic data, the spectral lines of these ions are simulated using a collisional radiative model. The amount of energy, transition data, and EIE collision strengths of high accuracy are significantly increased for several B-like ions of astrophysical interest, where experimental data are still very scarce. The results can be used in line identification, plasma modeling, and diagnostics of astrophysical plasmas.
- ID:
- ivo://CDS.VizieR/J/AJ/159/43
- Title:
- Spectroscopically identified CVs from LAMOST survey. I.
- Short Name:
- J/AJ/159/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A sample of cataclysmic variables (CVs) is presented including spectroscopically identified 380 spectra of 245 objects, of which 58 CV candidates are new discoveries. The BaggingTopPush and the Random Forest algorithms are applied to the Fifth Data Release (DR5) of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) to retrieve CVs with strong emission lines and with broad absorption lines respectively. Based on spectroscopic classification, 134 dwarf novae, 41 nova-like variables, and 19 magnetic CVs are identified from the sample. In addition, 89 high-inclination systems and 33 CVs showing companion stars are recognized and discussed for their distinct spectral characteristics. Comparisons between CVs from LAMOST and from published catalogs are made in spatial and magnitude distribution, and the difference of their locus in the Gaia color-absolute magnitude diagram (CaMD) are also investigated. More interestingly, for two dwarf novae observed through LAMOST and SDSS in different epochs, their spectra both in quiescence phase and during outburst are exhibited.
- ID:
- ivo://CDS.VizieR/III/137
- Title:
- Spectroscopically Identified Hot Subdwarf Stars
- Short Name:
- III/137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains data for 1225 spectroscopically classified hot subdwarf stars. It excludes central stars of planetary nebulae but includes stars in binary systems. The data assembled include, where available, alternative designations, accurate coordinates, UBV and uvby photometry, spectral types and determinations of effective temperature and surface gravity.
- ID:
- ivo://CDS.VizieR/B/wd
- Title:
- Spectroscopically identified white dwarfs
- Short Name:
- B/wd
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is an update of the Villanova catalog published in the ApJS paper, corresponding to the Web version of the catalog in Apr 2014 (see http://www.astronomy.villanova.edu/WDCatalog/index.html). The introduction to the 1999 catalog is in the file "preface.tex". This updated version lists 14294 unique white dwarfs for a total of 27975 rows (multiple observations).
- ID:
- ivo://CDS.VizieR/III/210
- Title:
- Spectroscopically Identified White Dwarfs
- Short Name:
- III/210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of 2249 white dwarfs which have been identified spectroscopically is presented complete through 1996 April. This compilation is the fourth edition of the Villanova Catalog of Spectroscopically Identified White Dwarfs. For each degenerate star, the following data entries with references are provided: (1) catalog coordinate designation or WD number, in order of right ascension; (2) the right ascension and declination for epoch 1950.0; (3) the spectral type based upon the new system; (4) a catalog symbol denoting binary membership; (5) a list of most names known to exist for a given star; (6) proper motion and position angle; (7) broad-band UBV Photometry, V, B-V, U-B; (8) multichannel spectrophotometry, V(MC), g-r; (9) Stroemgren narrow-band photometry y, b-y, u-b; (10) an absolute visual magnitude based upon the best available color-magnitude calibration or trigonometric parallax; (11) the observed radial velocity uncorrected for gravitational redshift or solar motion; and (12) the trigonometric parallax with mean error when available. A Notes section for unusual or peculiar stars and a coded Reference Key alphabetized by the first author's last name are presented, as well as an expanded table cross-referencing all names to catalog WD number. An introduction and full descriptions of the entries are provided in the text.
- ID:
- ivo://CDS.VizieR/III/235B
- Title:
- Spectroscopically Identified White Dwarfs
- Short Name:
- III/235B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is an update of the Villanova catalog published in the ApJS paper, corresponding to the Web version of the catalog in August 2006 (see http://www.astronomy.villanova.edu/WDCatalog/index.html). The introduction to the 1999 catalog is in the file "preface.tex". This version includes many additions and corrections to the original 4th edition: additional entries (555 newly discovered white dwarfs), additional data for previously known white dwarfs (marked in the catalog); new SDSS photometry has also been added. The total number of white dwarfs in this version is 5557.
- ID:
- ivo://CDS.VizieR/III/129
- Title:
- Spectroscopically Identified White Dwarfs
- Short Name:
- III/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This compilation is an expanded and updated version to the second edition of the catalogue (Mc Cook and Sion 1984); it includes 1282 stars. Please refer to the introduction by the authors (file "intro.txt"), to the documentation of the computer-readable version by W.H. Warren (file "adc.txt" or "adc.tex"), and to the original paper for an extensive description.