- ID:
- ivo://CDS.VizieR/J/ApJ/794/107
- Title:
- Distance to NGC6822 with Spitzer/FourStar Photometry
- Short Name:
- J/ApJ/794/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a revised distance to the nearby galaxy NGC 6822 using a new multi-band fit to both previously published and new optical, near-, and mid-infrared data for Cepheid variables. The new data presented in this study include multi-epoch observations obtained in 3.6 {mu}m and 4.5 {mu}m with the Spitzer Space Telescope taken for the Carnegie Hubble Program. We also present new observations in J, H, and K_s_ with FourStar on the Magellan Baade Telescope at Las Campanas Observatory. We determine mean magnitudes and present new period-luminosity relations in V, I, J, H, K_s_, Infrared Array Camera 3.6 {mu}m, and 4.5 {mu}m. In addition to using the multi-band distance moduli to calculate extinction and a true distance, we present a new method for determining an extinction-corrected distance modulus from multi-band data with varying sample sizes. We combine the distance moduli and extinction for individual stars to determine E(B-V)=0.35+/-0.04 and a true distance modulus {mu}_o_=23.38+/-0.02_stat_+/-0.04_sys_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/855/43
- Title:
- Distant RR Lyrae stars discovered with HiTS
- Short Name:
- J/ApJ/855/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of distant RR Lyrae stars, including the most distant known in the Milky Way, using data taken in the g-band with the Dark Energy Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We detect a total of 173 RR Lyrae stars over a ~120deg^2^ area, including both known RR Lyrae and new detections. The heliocentric distances dH of the full sample range from 9 to >200kpc, with 18 of them beyond 90kpc. We identify three sub-groups of RR Lyrae as members of known systems: the Sextans dwarf spheroidal galaxy, for which we report 46 new discoveries, and the ultra-faint dwarf galaxies Leo IV and Leo V. Following an MCMC methodology, we fit spherical and ellipsoidal profiles of the form {rho}(R)~Rn to the radial density distribution of RR Lyrae in the Galactic halo. The best fit corresponds to the spherical case, for which we obtain a simple power-law index of n=-4.17_-0.20_^+0.18^, consistent with recent studies made with samples covering shorter distances. The pulsational properties of the outermost RR Lyrae in the sample (dH>90kpc) differ from the ones in the halo population at closer distances. The distribution of the stars in a period-amplitude diagram suggest they belong to Oosterhoff-intermediate or Oosterhoff II groups, similar to what is found in the ultra-faint dwarf satellites around the Milky Way. The new distant stars discovered represent an important addition to the few existing tracers of the Milky Way potential in the outer halo.
- ID:
- ivo://CDS.VizieR/J/AJ/141/122
- Title:
- DK Lac V light curves
- Short Name:
- J/AJ/141/122
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on extensive photometry of DK Lac obtained during the interval 1990-2009, which includes a 2mag low state during 2001-2003. Much of the photometry consists of exposures obtained with a typical spacing of several days, but also includes 26 sequences of continuous photometry each lasting 2-7hr. We find no evidence for periodicities in our data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/397/350
- Title:
- DM Cyg BVIc light curves
- Short Name:
- J/MNRAS/397/350
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DM Cyg, a fundamental mode RRab star, was observed in the 2007 and 2008 seasons in the framework of the Konkoly Blazhko Survey. Very small amplitude light-curve modulation was detected with 10.57d modulation period. The maximum brightness and phase variations do not exceed 0.07mag and 7min, respectively. In spite of the very small amplitude of the modulation, beside the frequency triplets characterizing the Fourier spectrum of the light curve, two quintuplet components were also identified. The accuracy and the good phase coverage of our observations made it possible to analyse the light curves at different phases of the modulation separately.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/7
- Title:
- dSph satellites of M31. I. Variables in And XIX
- Short Name:
- J/ApJ/779/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B, V time-series photometry of Andromeda XIX (And XIX), the most extended (half-light radius of 6.2') of Andromeda's dwarf spheroidal companions, which we observed with the Large Binocular Cameras at the Large Binocular Telescope. We surveyed a 23'x23' area centered on And XIX and present the deepest color-magnitude diagram (CMD) ever obtained for this galaxy, reaching, at V~26.3mag, about one magnitude below the horizontal branch (HB). The CMD shows a prominent and slightly widened red giant branch, along with a predominantly red HB, which extends to the blue to significantly populate the classical instability strip. We have identified 39 pulsating variable stars, of which 31 are of RR Lyrae type and 8 are Anomalous Cepheids (ACs). Twelve of the RR Lyrae variables and three of the ACs are located within And XIX's half light radius. The average period of the fundamental mode RR Lyrae stars (<P_ab_>{=}0.62days, {sigma}=0.03days) and the period-amplitude diagram qualify And XIX as an Oosterhoff-Intermediate system. From the average luminosity of the RR Lyrae stars (<V(RR)>=25.34mag, {sigma}=0.10mag), we determine a distance modulus of (m-M)_0_=24.52+/-0.23mag in a scale where the distance to the Large Magellanic Cloud (LMC) is 18.5+/-0.1mag. The ACs follow a well-defined Period-Wesenheit (PW) relation that appears to be in very good agreement with the PW relationship defined by the ACs in the LMC.
- ID:
- ivo://CDS.VizieR/J/ApJ/877/49
- Title:
- DUSTiNGS. V. 3.6 and 4.5um light curves
- Short Name:
- J/ApJ/877/49
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) has identified hundreds of candidate dust-producing asymptotic giant branch (AGB) stars in several nearby metal-poor galaxies. We have obtained multi-epoch follow-up observations for these candidates with the Spitzer Space Telescope and measured their infrared (IR) light curves. This has allowed us to confirm their AGB nature and investigate pulsation behavior at very low metallicity. We have obtained high-confidence pulsation periods for 88 sources in seven galaxies. We have confirmed DUSTiNGS variable star candidates with a 20% success rate and determined the pulsation properties of 19 sources already identified as thermally pulsing AGB stars. We find that the AGB pulsation properties are similar in all galaxies surveyed here, with no discernible difference between the DUSTiNGS galaxies (down to 1.4% solar metallicity; [Fe/H]=-1.85) and the far more metal-rich Magellanic Clouds (up to 50% solar metallicity; [Fe/H]=-0.38). These results strengthen the link between dust production and pulsation in AGB stars and establish the IR period-luminosity relation as a reliable tool (+/-4%) for determining distances to galaxies, regardless of metallicity.
- ID:
- ivo://CDS.VizieR/J/AJ/115/1856
- Title:
- Dwarf Cepheids in Carina
- Short Name:
- J/AJ/115/1856
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have discovered 20 dwarf Cepheids (DCs) in the Carina dwarf spheroidal galaxy from an analysis of individual CCD images obtained for a deep photometric study of the system. These short-period pulsating variable stars are by far the most distant (~100kpc) and faintest (V~23.0) DCs known. The Carina DCs obey a well-defined period-luminosity relation, allowing us to readily distinguish between overtone and fundamental pulsators in nearly every case. Unlike RR Lyrae stars, the pulsation mode turns out to be uncorrelated with light-curve shape, and the overtone pulsators do not tend toward shorter periods compared with the fundamental pulsators. Using the period-luminosity relations from Nemec, Nemec, & Lutz (1994, Cat. <J/AJ/108/222> and McNamara (1995AJ....109.1751M), we derive (m-M)_0_=20.06+/-0.12, for E(B-V)=0.025 and [Fe/H]=-2.0, in good agreement with recent, independent estimates of the distance/reddening of Carina. The error reflects the uncertainties in the DC distance scale, and in the metallicity and reddening of Carina. The frequency of DCs among upper-main-sequence stars in Carina is approximately 3%. The ratio of dwarf Cepheids to RR Lyrae stars in Carina is 0.13+/-0.10, though this result is highly sensitive to the star formation history of Carina and the evolution of the horizontal branch.
228. DX Eri variability
- ID:
- ivo://CDS.VizieR/J/A+A/309/787
- Title:
- DX Eri variability
- Short Name:
- J/A+A/309/787
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of nearly simultaneous monitoring of uvby light and HeI667.81nm line-profile variations of the equatorial Be star DX Eri in November 1991. They are analysed along with numerous uvby photometry in the period 1986-1995.
- ID:
- ivo://CDS.VizieR/J/other/JAD/25.1
- Title:
- EE Cam, FG Vir and 44 Tau light curves
- Short Name:
- J/other/JAD/25.1
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The three delta Scuti pulsators EE Cam, FG Vir and 44 Tau are of special interest because their pulsation properties are different from those expected from the low rotational velocities indicated by spectroscopic measurements. This paper presents the previously unpublished high-precision photometric data obtained by the Delta Scuti Network during 780 nights.
- ID:
- ivo://CDS.VizieR/J/A+A/371/579
- Title:
- Empirical relations for cluster RR Lyrae
- Short Name:
- J/A+A/371/579
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our former study on the empirical relations between the Fourier parameters of the light curves of the fundamental mode RR Lyrae stars and their basic stellar parameters has been extended to considerably larger data sets. The most significant contribution to the absolute magnitude M_V_ comes from the period P and from the first Fourier amplitude A_1_, but there are statistically significant contributions also from additional higher order components, most importantly from A_3_ and in a lesser degree from the Fourier phase phi_51_. When different colors are combined in reddening-free quantities, we obtain basically period-luminosity-color relations. From the standard deviations of the various regressions, an upper limit can be obtained on the overall inhomogeneity of the reddening in the individual clusters. This yields {sigma}_E(B-V)_<0.012mag, which also implies an average minimum observational error of {sigma}_V_>0.018mag.