- ID:
- ivo://CDS.VizieR/J/MNRAS/462/4349
- Title:
- Variable stars in Sculptor dSph
- Short Name:
- J/MNRAS/462/4349
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the identification of 634 variable stars in the Milky Way dwarf spheroidal (dSph) satellite Sculptor based on archival ground-based optical observations spanning ~24yr and covering ~2.5deg^2^. We employed the same methodologies as the 'Homogeneous Photometry' series published by Stetson. In particular, we have identified and characterized one of the largest (536) RR Lyrae samples so far in a Milky Way dSph satellite. We have also detected four Anomalous Cepheids, 23 SX Phoenicis stars, five eclipsing binaries, three field variable stars, three peculiar variable stars located above the horizontal branch - near to the locus of BL Herculis - that we are unable to classify properly. Additionally, we identify 37 long period variables plus 23 probable variable stars, for which the current data do not allow us to determine the period. We report positions and finding charts for all the variable stars, and basic properties (period, amplitude, mean magnitude) and light curves for 574 of them. We discuss the properties of the RR Lyrae stars in the Bailey diagram, which supports the coexistence of subpopulations with different chemical compositions. We estimate the mean mass of Anomalous Cepheids (~1.5M_{sun}_) and SX Phoenicis stars (~1M_{sun}_). We discuss in detail the nature of the former. The connections between the properties of the different families of variable stars are discussed in the context of the star formation history of the Sculptor dSph galaxy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/829/26
- Title:
- Variable stars in the field of Andromeda XXV. III.
- Short Name:
- J/ApJ/829/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B and V time series photometry of Andromeda XXV, the third galaxy in our program on the Andromeda's satellites, which we have imaged with the Large Binocular Cameras of the Large Binocular Telescope. The field of Andromeda XXV is found to contain 62 variable stars, for which we present light curves and characteristics of the light variation (period, amplitudes, variability type, mean magnitudes, etc.). The sample includes 57 RR Lyrae variables (46 fundamental-mode-RRab, and 11 first-overtone-RRc, pulsators), 3 anomalous Cepheids, 1 eclipsing binary system, and 1 unclassified variable. The average period of the RRab stars (<Pab>=0.60 {sigma}=0.04d) and the period-amplitude diagram place Andromeda XXV in the class of the Oosterhoff-Intermediate objects. From the average luminosity of the RR Lyrae stars we derive for the galaxy a distance modulus of (m-M)_0_=24.63+/-0.17mag. The color-magnitude diagram reveals the presence in Andromeda XXV of a single, metal-poor ([Fe/H]=-1.8dex) stellar population as old as ~10-12Gyr, traced by a conspicuous red giant branch and the large population of RR Lyrae stars. We discovered a spherically shaped high density of stars near the galaxy center. This structure appears to be at a distance consistent with Andromeda XXV and we suggest it could either be a star cluster or the nucleus of Andromeda XXV. We provide a summary and compare the number and characteristics of the pulsating stars in the M31 satellites analyzed so far for variability.
- ID:
- ivo://CDS.VizieR/J/AJ/159/121
- Title:
- V-band light curve & RVs of the Cepheid V473Lyr
- Short Name:
- J/AJ/159/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V473Lyr is a classical Cepheid that is unique in having substantial amplitude variations with a period of approximately 3.3yr, thought to be similar to the Blazhko variations in RR Lyrae stars. We obtained an X-ray Multi-Mirror Mission (XMM)-Newton observation of this star to follow up a previous detection in X-rays. Rather than the X-ray burst and rapid decline near maximum radius seen in {delta}Cephei itself, the X-ray flux in V473Lyr remained constant for a third of the pulsation cycle covered by the observation. Thus the X-rays are probably not produced by the changes around the pulsation cycle. The X-ray spectrum is soft (kT=0.6keV), with X-ray properties consistent with a young low-mass companion. Previously there was no evidence of a companion in radial velocities or in Gaia and Hipparcos proper motions. While this rules out companions that are very close or very distant, a binary companion at a separation between 30 and 300au is possible. This is an example of an X-ray observation revealing evidence of a low-mass companion, which is important in completing the mass ratio statistics of binary Cepheids. Furthermore, the detection of a young X-ray bright companion is a further indication that the Cepheid (primary) is a Population I star, even though its pulsation behavior differs from other classical Cepheids.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/23
- Title:
- V-band photometric follow-up of RR Lyrae from SEKBO
- Short Name:
- J/ApJ/756/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the steepening of the power-law slope beyond the Galactocentric radius of R~45kpc in the RR Lyrae (RRL) space density distribution found by Keller et al. (2008, Cat. J/ApJ/678/851). They identified 2016 RRL candidates derived from the analysis of archival observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey. Our aim is to verify the completeness of RRLs and ultimately the space density distribution function given by Keller et al. We followed up on a subset of 137 candidates with a range of magnitudes (V~14-20) using the Faulkes Telescope (FT) database and confirmed 57 candidates as real RRLs. A cross-match between SEKBO RRL survey and Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL candidates in common. Applying the color selection criteria proposed by Ivezi\'c et al. (2005AJ....129.1096I) resulted in 193 likely RRLs. The completeness as a function of magnitude was calculated empirically from the combined set of SEKBO RRL candidates from current FT data, SDSS cross-matched data, and the Prior et al. catalog (2009, Cat. J/ApJ/691/306). This resulted in a spatial density distribution characterized by two power laws with a break radius R within a range between 45kpc and 50kpc, similar to the results of Keller et al. We find the power-law slopes for the inner halo as n_inner_=-2.78+/-0.02 and for the outer halo as n_outer_=-5.0+/-0.2.
- ID:
- ivo://CDS.VizieR/J/A+AS/106/79
- Title:
- VBLUW and UBV Photometry of IL Vel
- Short Name:
- J/A+AS/106/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/265/77
- Title:
- VBLUW Observations of TT Ari
- Short Name:
- J/A+A/265/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- TT Ari was observed in the 5 passbands VBLUW (544, 430, 384, 362 and 324nm) during 3 nights on the 90cm telescope at ESO (La Silla), between July and November 1988, with an integration time of 16s.
- ID:
- ivo://CDS.VizieR/J/A+A/445/617
- Title:
- V823 Cas BV(RI)c differential photometry
- Short Name:
- J/A+A/445/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0+f2=2f1 resonance may act in triple mode pulsators.
- ID:
- ivo://CDS.VizieR/J/other/RAA/17.20
- Title:
- V977 Cep and V982 Cep long-term photometry
- Short Name:
- J/other/RAA/17.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Long-term BVRI photometric light curves of the pre-main sequence stars V977 Cep and V982 Cep during the period from 2000 October to 2016 August are presented. The stars are located in the vicinity of the reflection nebula NGC 7129. Our photometric data show that both stars exhibit strong photometric variability in all optical passbands, which is typical for Classical T Tauri stars. Using our observational data we analyze the reasons for the observed brightness variations. In the case of V977 Cep we identify previously unknown periodicity in its light curve.
- ID:
- ivo://CDS.VizieR/J/other/RAA/14.1264
- Title:
- V350 Cep UBVRI long-term photometry
- Short Name:
- J/other/RAA/14.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results from UBVRI optical photometric observations of the pre-main sequence star V350 Cep during the period 2004-2014 are presented. The star was discovered in 1977 due to its remarkable increase in brightness by more than 5mag (R). In previous studies, V350 Cep is considered to be a potential FUor or EXor eruptive variable. Our data suggest that during the period of observations the star keeps its maximum brightness with low amplitude photometric variations. Our conclusion is that V350 Cep is probably an intermediate object between FUors and EXors, similar to V1647 Ori.
- ID:
- ivo://CDS.VizieR/J/A+A/350/513
- Title:
- V368 Cep UBVRI time series
- Short Name:
- J/A+A/350/513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our time series analysis of V368 Cep photometry ascertains the rotation period of 2.74d uniquely. The manifestations of starspot induced luminosity variations in this chromospherically active star include rapid light curve changes and differential rotation of about 3%. We conclude that the single rapidly rotating variable V368 Cep is a high inclination K1V post T Tauri star.