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- ID:
- ivo://CDS.VizieR/J/PAZh/23/454
- Title:
- Identification and coordinates in M 53
- Short Name:
- J/PAZh/23/454
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Equatorial coordinates have been determined for 61 variables in the northern globular cluster M 53 and for 12 variables in the southern globular cluster NGC 2808 with accuracy sufficient for reliable identifications. A number of errors have been revealed in publications on variable starts in M 53.
- ID:
- ivo://CDS.VizieR/IV/29
- Title:
- Identification of Dahlmark variables
- Short Name:
- IV/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The amateur observer Lennart Dahlmark has published a useful series of IBVS notes listing a number of candidate variable stars, most of which were new. Although adequate charts and reliable semi-accurate positions were supplied, no other identifications were usually given. If the stars are to be recovered for further study and linkage within other surveys (IRAS, etc.), then precise positions must be determined to make identification unambiguous within crowded galactic fields.
- ID:
- ivo://CDS.VizieR/J/AJ/158/16
- Title:
- Identification of RR Lyrae stars from the DES
- Short Name:
- J/AJ/158/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many studies have shown that RR Lyrae variable stars (RRL) are powerful stellar tracers of Galactic halo structure and satellite galaxies. The Dark Energy Survey (DES), with its deep and wide coverage (g~23.5 mag in a single exposure; over 5000 deg^2^) provides a rich opportunity to search for substructures out to the edge of the Milky Way halo. However, the sparse and unevenly sampled multiband light curves from the DES wide-field survey (a median of four observations in each of grizY over the first three years) pose a challenge for traditional techniques used to detect RRL. We present an empirically motivated and computationally efficient template-fitting method to identify these variable stars using three years of DES data. When tested on DES light curves of previously classified objects in SDSS stripe 82, our algorithm recovers 89% of RRL periods to within 1% of their true value with 85% purity and 76% completeness. Using this method, we identify 5783 RRL candidates, ~28% of which are previously undiscovered. This method will be useful for identifying RRL in other sparse multiband data sets.
- ID:
- ivo://CDS.VizieR/IV/23
- Title:
- Identifications of Sonneberg variables
- Short Name:
- IV/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list below is a continuation of a series providing accurate positions and identifications for variables appearing on the MVS charts (Hoffmeister, 1957, Mitt. Verdander. Sterne, No. 245). The variables here were first described by Hoffmeister (1949, Astron. Abh. Ergaenzungshefte z.d. Astron. Nach., 12, no. 1, A3) in the difficult-to-find ``Ergaenzungshefte'' to the Astronomische Nachrichten, and are the first group from a collection of some 1440 variables from this publication. Details about the identification procedure and table layout are contained in the first report of our series (Kinnunen & Skiff, 2000IBVS.4862....1K). We are grateful to librarians Antoinette Beiser (Lowell) and Brenda Corbin (U. S. Naval Observatory, Washington) for providing a photocopy of the Hoffmeister survey; ``bibliothecaire extraordinaire'' Suzanne Laloe (Obs. Paris-Meudon) advised on how this obscure journal should be cited.
- ID:
- ivo://CDS.VizieR/J/A+A/625/A27
- Title:
- II Pegasi spectra with PEPSI
- Short Name:
- J/A+A/625/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a temperature and a magnetic-field surface map of the K2 subgiant of the active binary II Peg. Employed are high resolution Stokes IV spectra obtained with the new Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT). Fourteen average line profiles are inverted using our iMap code. We have employed an iterative regularization scheme without the need of a penalty function and incorporate a physical 3D description of the surface field vector. The spectral resolution of our data is 130000 which converts to 20 resolution elements across the disk of II Peg. Our main result is that the temperature features on II Peg closely correlate with its magnetic field topology. We find a warm spot (350K warmer with respect to the effective temperature) of positive polarity and radial field density of 1.1kG coexisting with a cool spot (780K cooler) of negative polarity of 2kG. Several other cool features are reconstructed containing both polarities and with (radial) field densities of up to 2kG. The largest cool spot is reconstructed with a temperature contrast of 550K, an area of almost 10% of the visible hemisphere, and with a multipolar magnetic morphology. A meridional and an azimuthal component of the field of up to +/-500G is detected in two surface regions between spots with strong radial fields but different polarities. A force-free magnetic-field extrapolation suggests that the different polarities of cool spots and the positive polarity of warm spots are physically related through a system of coronal loops of typical height of ~=2R*. While the H{alpha} line core and its red-side wing exhibit variations throughout all rotational phases, a major increase of blue-shifted H{alpha} emission was seen for the phases when the warm spot is approaching the stellar central meridian indicating high-velocity mass motion within its loop. Active stars such as II Peg can show coexisting cool and warm spots on the surface that we interpret resulting from two different formation mechanisms. We explain the warm spots due to photospheric heating by a shock front from a siphon-type flow between regions of different polarities while the majority of the cool spots is likely formed due to the expected convective suppression like on the Sun.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A97
- Title:
- II Pegasus photometry during 1979-2010
- Short Name:
- J/A+A/559/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- According to earlier Doppler images of the magnetically active primary giant component of the RS CVn binary II Peg, the surface of the star was dominated by one single active longitude that was clearly drifting in the rotational frame of the binary system during 1994-2002; later imaging for 2004-2010, however, showed decreased and chaotic spot activity, with no signs of the drift pattern. Here we set out to investigate from a more extensive photometric dataset whether such a drift is a persistent phenomenon, in which case it could be due to either an azimuthal dynamo wave or an indication of the binary system orbital synchronization still being incomplete. We analyse the datasets using the Carrier Fit method (hereafter CF), especially suitable for analyzing time series in which a fast clocking frequency (such as the rotation of the star) is modulated with a slower process (such as the stellar activity cycle).
- ID:
- ivo://CDS.VizieR/J/A+A/362/215
- Title:
- IJKs photometry of Galactic bulge variables
- Short Name:
- J/A+A/362/215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Repeated DENIS observations (summer 1996 & 1998) in the J (1.25{mu}m) and the K_s_ (2.15{mu}m) bands are used to look for variables stars. We present two catalogues of ~1000 probable variables in an area of ~4deg^2^ of the inner galactic bulge. The first one contains ~720 variable star candidates which which show variability in the J and K_s_ while the second consists of sources only observed to be variable in K_s_ (~270 sources), mainly in regions whit high interstellar extinction.
- ID:
- ivo://CDS.VizieR/J/other/PZP/9.5
- Title:
- I light curves of RR Lyrae from OGLE II
- Short Name:
- J/other/PZP/9.5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the discovery of ten RR Lyrae variables. They were found in a search for new variables in the OGLE II Photometric Database (Szymanski 2005AcA....55...43S, Udalski et al. 1997AcA....47..319U). Suitable parameters (e.g. Isig>0.1, e_Imed<Isig) were used in the OGLE Photometry Database Query Page (http://ogledb.astrouw.edu.pl/~ogle/photdb/) for stars in the Galactic Disk. Period analysis was made with the software AVE (GEA).
- ID:
- ivo://CDS.VizieR/J/A+A/654/A157
- Title:
- 5 ILRTs light curves and spectra
- Short Name:
- J/A+A/654/A157
- Date:
- 07 Mar 2022 07:10:34
- Publisher:
- CDS
- Description:
- We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between -11:5 and -14:5mag. Their pseudo-bolometric light curves peak in the range 0.5-9.0*10^40^erg/s and their total radiated energies are on the order of (0.3-3)*10^47^erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the ^56^Co decay. If the late-time power source is indeed radioactive decay, these transients produce ^56^Ni masses on the order of 10^-4^ to 10^-3^M_{sun}_. The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km/s, along with CaII features. In particular, the [CaII]7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events.
