A Catalog of Accurate Equatorial Coordinates for Variable Stars in Globular Clusters

Samus, N. N.; Kazarovets, E. V.; Pastukhova, E. N.; Tsvetkova, T. M.; Durlevich, O. V.

doi:10.1086/649432

Cited by 50 publications

(53 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…White circles and labels indicate the locations of the variables, and each of the variables we detect in our data is shown in an individual stamp, its location marked by a cross-hair. V2 and V8 are saturated in our reference image and therefore we do not present light curves for them, but their locations are shown on this finding chart using the coordinates of Samus et al (2009) marked. Although in theory a deeper CMD could be obtained by combining many images, in practice the large variations in seeing and the number of images with significantly worse seeing than the reference image makes this impractical in this case.…”

Section: Variable Propertiesmentioning

confidence: 99%

Constraining the parameters of globular cluster NGC 1904 from its variable star population

Kains

Bramich

Jaimes

et al. 2012

A&A

View full text Add to dashboard Cite

Aims. We present the analysis of 11 nights of V and I time-series observations of the globular cluster NGC 1904 (M 79). Using this we searched for variable stars in this cluster and attempted to refine the periods of known variables, making use of a time baseline spanning almost 8 years. We use our data to derive the metallicity and distance of NGC 1904. Methods. We used difference imaging to reduce our data to obtain high-precision light curves of variable stars. We then estimated the cluster parameters by performing a Fourier decomposition of the light curves of RR Lyrae stars for which a good period estimate was possible.Results. Out of 13 stars previously classified as variables, we confirm that 10 are bona fide variables. We cannot detect variability in one other within the precision of our data, while there are two which are saturated in our data frames, but we do not find sufficient evidence in the literature to confirm their variability. We also detect a new RR Lyrae variable, giving a total number of confirmed variable stars in NGC 1904 of 11. Using the Fourier parameters, we find a cluster metallicity [Fe/H] ZW = −1.63 ± 0.14, or [Fe/H] UVES = −1.57 ± 0.18, and a distance of 13.3 ± 0.4 kpc (using RR0 variables) or 12.9 kpc (using the one RR1 variable in our sample for which Fourier decomposition was possible).

show abstract

Section: Variable Propertiesmentioning

confidence: 99%

Constraining the parameters of globular cluster NGC 1904 from its variable star population

Kains

Bramich

Jaimes

et al. 2012

A&A

View full text Add to dashboard Cite

show abstract

“…RU Vir is a C-rich AGB Variable Star of Mira type. It has a period of 433.2 days in the V-band (Samus et al 2009). Its distance is 910 pc (based on the period-luminosity relation from Table 1.…”

Section: Introductionmentioning

confidence: 99%

Modelling the atmosphere of the carbon-rich Mira RU Virginis

Rau

Paladini

Hron

et al. 2015

A&A

View full text Add to dashboard Cite

Context. We study the atmosphere of the carbon-rich Mira RU Vir using the mid-infrared high spatial resolution interferometric observations from VLTI/MIDI. Aims. The aim of this work is to analyse the atmosphere of the carbon-rich Mira RU Vir with hydrostatic and dynamic models, in this way deepening the knowledge of the dynamic processes at work in carbon-rich Miras. Methods. We compare spectro-photometric and interferometric measurements of this carbon-rich Mira AGB star with the predictions of different kinds of modelling approaches (hydrostatic model atmospheres plus MOD-More Of Dusty, self-consistent dynamic model atmospheres). A geometric model fitting tool is used for a first interpretation of the interferometric data. Results. The results show that a joint use of different kinds of observations (photometry, spectroscopy, interferometry) is essential for shedding light on the structure of the atmosphere of a carbon-rich Mira. The dynamic model atmospheres fit the ISO spectrum well in the wavelength range λ = [2.9, 25.0] µm. Nevertheless, a discrepancy is noticeable both in the SED (visible) and in the interferometric visibilities (shape and level), which is a possible explanation are intra-/inter-cycle variations in the dynamic model atmospheres, as well as in the observations. The presence of a companion star and/or a disk or a decrease in mass loss within the past few hundred years cannot be excluded, but these explanations are considered unlikely.

show abstract

“…High-precision multicolor photometric star catalogs are in great demand in a substantial part of astronomy and its applications, and the studies cited here (Gorynya et al 1996;Shakura et al 1998;Popov & Prokhorov 2006;Samus et al 2009;Sil'chenko et al 2012), which we selected based on our subjective opinion, cover only a small part of the applications of these catalogs.…”

Section: Discussionmentioning

confidence: 99%

Mathematical Problems in Creating Large Astronomical Catalogs

et al. 2016

View full text Add to dashboard Cite

Abstract. The next stage after performing observations and their primary reduction is to transform the set of observations into a catalog. To this end, objects that are irrelevant to the catalog should be excluded from observations and gross errors should be discarded. To transform such a prepared data set into a high-precision catalog, we need to identify and correct systematic errors. Therefore, each object of the survey should be observed several, preferably many, times. The problem formally reduces to solving an overdetermined set of equations. However, in the case of catalogs this system of equations has a very specific form: it is extremely sparse, and its sparseness increases rapidly with the number of objects in the catalog. Such equation systems require special methods for storing data on disks and in RAM, and for the choice of the techniques for their solving. Another specific feature of such systems is their high "stiffness", which also increases with the volume of a catalog. Special stable mathematical methods should be used in order not to lose precision when solving such systems of equations. We illustrate the problem by the example of photometric star catalogs, although similar problems arise in the case of positional, radial-velocity, and parallax catalogs.

show abstract

A Catalog of Accurate Equatorial Coordinates for Variable Stars in Globular Clusters

Cited by 50 publications

References 7 publications

Constraining the parameters of globular cluster NGC 1904 from its variable star population

Constraining the parameters of globular cluster NGC 1904 from its variable star population

Modelling the atmosphere of the carbon-rich Mira RU Virginis

Mathematical Problems in Creating Large Astronomical Catalogs

Contact Info

Product

Resources

About