- ID:
- ivo://CDS.VizieR/J/PAZh/36/281
- Title:
- Variability of 3 protoplanetary nebulae
- Short Name:
- J/PAZh/36/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new photometric data and analyze long-term UBV observations of three candidates for protoplanetary nebulae - F supergiants with infrared excesses at high Galactic latitudes -IRAS 18095+2704, IRAS 19386+0155, and IRAS 19500-1709. All these stars exhibit quasi-periodic low-amplitude variations caused by pulsations against the background of long-term brightness trends. For IRAS 18095+2704 = V887 Her, we have found a pulsation period of 109 days and revealed a linear brightness trend - the star brightens at constant (within the limits of the measurement errors) yearly mean color indices. The light curve of IRAS 19386+0155 = V1648 Aql in 2000-008 is represented by a wave with a fundamental period of 102 days whose modulation with a close period of 98 days leads to variations with a variable amplitude. V1648 Aql also shows a systematic rise in V brightness along with a reddening. IRAS 19500-1709 = V5112 Sgr exhibits irregular pulsations with periods of 39 and 47 days. The long-term variability component of V5112 Sgr may indicate that the star is binary.
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- ID:
- ivo://CDS.VizieR/J/ApJ/859/73
- Title:
- Variability of RSGs in M31 from the iPTF survey
- Short Name:
- J/ApJ/859/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Most massive stars end their lives as red supergiants (RSGs), a short-lived evolutionary phase when they are known to pulsate with varying amplitudes. The RSG period-luminosity (PL) relation has been measured in the Milky Way, the Magellanic Clouds and M33 for about 120 stars in total. Using over 1500 epochs of R-band monitoring from the Palomar Transient Factory survey over a five-year period, we study the variability of 255 spectroscopically cataloged RSGs in M31. We find that all RGSs brighter than M_K_~-10mag (log(L/L_{sun}_)>4.8) are variable at {Delta}m_R_>0.05mag. Our period analysis finds 63 with significant pulsation periods. Using the periods found and the known values of M_K_ for these stars, we derive the RSG PL relation in M31 and show that it is consistent with those derived earlier in other galaxies of different metallicities. We also detect, for the first time, a sequence of likely first-overtone pulsations. Comparison to stellar evolution models from MESA confirms the first-overtone hypothesis and indicates that the variable stars in this sample have 12M_{sun}_<M<24M_{sun}_. As these RSGs are the immediate progenitors to Type II-P core-collapse supernovae (SNe), we also explore the implication of their variability in the initial-mass estimates for SN progenitors based on archival images of the progenitors. We find that this effect is small compared to the present measurement errors.
- ID:
- ivo://CDS.VizieR/J/A+A/562/A79
- Title:
- Variability of seven blazars in six bands
- Short Name:
- J/A+A/562/A79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the light curves of six BL Lac objects, PKS 0537-441, PKS 0735+17, OJ 287, PKS 2005-489, PKS 2155- 304, W Comae, and of the Flat Spectrum Radio Quasar PKS 1510-089, as a part of a photometric monitoring program in the near-infrared/optical bands started in 2004. All sources are Fermi Blazars. Our purpose is to investigate flux and spectral variability at short and long time scales. Systematic monitoring, independent of the activity of the source, guarantees high statistics, and allows to draw an unbiased view of different activity states on weekly/daily time scales for the whole timeframe, and on nightly timescales for some epochs. Data were obtained with the REM telescope located at the ESO premises of La Silla (Chile). Light curves were gathered in the optical/near-infrared VRIJHK bands from 2005 April to 2012 June. Variability >~3mag is observed in PKS 0537-441, PKS 1510-089 and PKS 2155-304, the largest ranges spanned in the near-infrared. The color intensity plots show rather different morphologies. The spectral energy distributions in general are well fitted by a power law, with some deviations which are more apparent in low states. Some variability episodes during a night interval are well documented for PKS 0537-441 and PKS 2155-304. For the latter source the variability time scale implies a large relativistic beaming factor.
7624. Variability of WR 86
- ID:
- ivo://CDS.VizieR/J/A+A/384/1012
- Title:
- Variability of WR 86
- Short Name:
- J/A+A/384/1012
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables present photometric monitoring of WR 86 in the Walraven VBLUW system during two nights in July 1989, three nights in May/June 1990 and six nights in June 1990, together with UBV photometry during one night in 1995. Radial velocity measurements of WR86 for six emission lines in 1989, three emission lines in 1995 and two absorption lines in 1995. Equivalent width measurements of WR86 for five emission lines in 1989 and three emission lines in 1995.
- ID:
- ivo://CDS.VizieR/J/A+A/353/77
- Title:
- Variability & polarization of luminous quasars
- Short Name:
- J/A+A/353/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use 250 radio loud quasars with UBV photometry available and z<1.65, to study whether there is a gap in the distribution of absolute magnitudes, from M_V_~-25.8 (for H_0_=100km/s/Mpc, q_0_=0.5) to -25.3, as was suggested by Teerikorpi (1981A&A....98..309T; Paper I). In Paper I it was also proposed that there is a class of the most luminous radio quasars, differing in some properties from fainter quasars on the other side of the gap. The main conclusion of Paper I remains intact. The gap in the distribution of absolute magnitudes is confirmed with the new formalism of cosmological Malmquist bias (Teerikorpi, 1998A&A...339..647T), which allows one to use heterogeneous samples with magnitude inhomogeneity.
- ID:
- ivo://CDS.VizieR/J/AJ/155/39
- Title:
- Variability properties of TIC sources with KELT
- Short Name:
- J/AJ/155/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kilodegree Extremely Little Telescope (KELT) has been surveying more than 70% of the celestial sphere for nearly a decade. While the primary science goal of the survey is the discovery of transiting, large-radii planets around bright host stars, the survey has collected more than 10^6^ images, with a typical cadence between 10-30 minutes, for more than four million sources with apparent visual magnitudes in the approximate range 7<V<13. Here, we provide a catalog of 52741 objects showing significant large-amplitude fluctuations likely caused by stellar variability, as well as 62229 objects identified with likely stellar rotation periods. The detected variability ranges in rms-amplitude from ~3 mmag to ~2.3 mag, and the detected periods range from ~0.1 to >~2000 days. We provide variability upper limits for all other ~4000000 sources. These upper limits are principally a function of stellar brightness, but we achieve typical 1{sigma} sensitivity on 30 min timescales down to ~5 mmag at V~8, and down to ~43 mmag at V~13. We have matched our catalog to the TESS Input catalog and the AAVSO Variable Star Index to precipitate the follow-up and classification of each source. The catalog is maintained as a living database on the Filtergraph visualization portal at the URL https://filtergraph.com/kelt_vars.
- ID:
- ivo://CDS.VizieR/J/A+A/503/1023
- Title:
- Variability Sample Catalogue from SOGS
- Short Name:
- J/A+A/503/1023
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A set of 55000 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892-1932 along the galactic equator section l{in}[275deg,335deg] with galactic latitude b{in}[-7deg,7deg]. Short-term (30min) and long-term (decades) magnitude variations in the data set are analyzed.
- ID:
- ivo://CDS.VizieR/J/A+A/488/73
- Title:
- Variability-selected AGN in Chandra DFS
- Short Name:
- J/A+A/488/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Variability is a property shared by virtually all active galactic nuclei (AGNs), and was adopted as a criterion for their selection using data from multi epoch surveys. Low Luminosity AGNs (LLAGNs) are contaminated by the light of their host galaxies, and cannot therefore be detected by the usual colour techniques. For this reason, their evolution in cosmic time is poorly known. Consistency with the evolution derived from X-ray detected samples has not been clearly established so far, also because the low luminosity population consists of a mixture of different object types. LLAGNs can be detected by the nuclear optical variability of extended objects. Several variability surveys have been, or are being, conducted for the detection of supernovae (SNe). We propose to re-analyse these SNe data using a variability criterion optimised for AGN detection, to select a new AGN sample and study its properties. We analysed images acquired with the wide field imager at the 2.2m ESO/MPI telescope, in the framework of the STRESS supernova survey. We selected the AXAF field centred on the Chandra Deep Field South where, besides the deep X-ray survey, various optical data exist, originating in the EIS and COMBO-17 photometric surveys and the spectroscopic database of GOODS.
- ID:
- ivo://CDS.VizieR/J/AcA/63/339
- Title:
- Variability Survey in Stock 14 cluster
- Short Name:
- J/AcA/63/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a photometric variability survey in the young open cluster Stock 14 and the surrounding fields. In total, we detected 103 variable stars of which 88 are new discoveries. We confirm short-period, low-amplitude light variations in two eclipsing members of the cluster, HD 101838 and HD 101794. In addition, we find two new {beta} Cep stars of which one, HD 101993, is also a member. The sample of pulsating cluster members is supplemented by one multimode slowly pulsating B-type star and several single-mode candidates of this type. The other pulsating stars in our sample are mostly field stars. In particular, we found 14 {delta} Sct stars including one {gamma} Dor/{delta} Sct hybrid pulsator.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/97
- Title:
- Variable AGNs in GOODS fields
- Short Name:
- J/ApJ/731/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify 85 variable galaxies in the GOODS North and South fields using five epochs of Hubble Space Telescope Advance Camera for Survey V-band (F606W) images spanning 6 months. The variables are identified through significant flux changes in the galaxy's nucleus and represent ~2% of the survey galaxies. With the aim of studying the active galaxy population in the GOODS fields, we compare the variability-selected sample with X-ray and mid-IR active galactic nucleus (AGN) candidates. Forty-nine percent of the variables are associated with X-ray sources identified in the 2Ms Chandra surveys. Twenty-four percent of X-ray sources likely to be AGNs are optical variables and this percentage increases with decreasing hardness ratio of the X-ray emission. Stacking of the non-X-ray-detected variables reveals marginally significant soft X-ray emission. Forty-eight percent of mid-IR power-law sources are optical variables, all but one of which is also X-ray detected. Thus, about half of the optical variables are associated with either X-ray or mid-IR power-law emission. The slope of the power-law fit through the Spitzer IRAC bands indicates that two-thirds of the variables have BLAGN-like spectral energy distributions. Among those galaxies spectroscopically identified as AGNs, we observe variability in 74% of broad-line AGNs and 15% of NLAGNs. The variables are found in galaxies extending to z~3.6.
