Luminosity–colour relations for red clump stars

Bilir, S.; Önal, Ö.; Karaali, S.; Cabrera-Lavers, A.; Çakmak, Hikmet

doi:10.1007/s10509-012-1342-9

Cited by 15 publications

(22 citation statements)

References 52 publications

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“…In all panels, among the bright and red stars half a dozen of them occupy the region where red clump (RC) stars lie, i.e. 0.7 ≤ (B − V ) 0 ≤ 1.2 mag (Bilir et al 2013a). These stars are important because they have been used as standard candles (i.e.…”

Section: Colour-magnitude Diagramsmentioning

confidence: 99%

“…The symbol "+" indicates the most probable value of the corresponding parameter that they can be used as standard candles in distance estimation of the objects associated with them (cf. Alves 2000; Grocholski and Sarajedini 2002;Groenewegen 2008;Yaz Gökçe et al 2013;Bilir et al 2013aBilir et al , 2013b. Groenewegen (2008) calculated the mean absolute magnitude for the RC stars as M K s = −1.54 ± 0.04 mag in the Two Micron Sky Survey (2MASS; Skrutskie et al 2006) photometric system, while the mean absolute magnitude in the V band is given by Keenan and Barnbaum (1999) as 0.7 ≤ M V ≤ 1 mag.…”

Section: Distance Via the Red Clump Starsmentioning

confidence: 99%

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CCD UBVRI photometry of NGC 6811

Yontan

Bilir

Bostancı

et al. 2015

Astrophys Space Sci

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We present the results of CCD UBVRI observations of the open cluster NGC 6811 obtained on 18th July 2012 with the 1m telescope at the T\"UB\.ITAK National Observatory (TUG). Using these photometric results, we determine the structural and astrophysical parameters of the cluster. The mean photometric uncertainties are better than 0.02 mag in the V magnitude and B-V, V-R, and V-I colour indices to about 0.03 mag for U-B among stars brighter than magnitude V=18. Cluster member stars were separated from the field stars using the Galaxia model of Sharma et al. (2011) together with other techniques. The core radius of the cluster is found to be $r_{c}$=3.60 arcmin. The astrophysical parameters were determined simultaneously via Bayesian statistics using the colour-magnitude diagrams V versus B-V, V versus V-I, V versus V-R, and V versus R-I of the cluster. The resulting most likely parameters were further confirmed using independent methods, removing any possible degeneracies. The colour excess, distance modulus, metallicity and the age of the cluster are determined simultaneously as E(B-V)=0.05$\pm$0.01 mag, $\mu=10.06\pm0.08$ mag, [M/H]=-0.10$\pm$0.01 dex and t=1.00$\pm$0.05 Gyr, respectively. Distances of five red clump stars which were found to be members of the cluster further confirm our distance estimation.Comment: 22 pages, 13 figures and 9 tables, accepted for publication in Astrophysics and Space Scienc

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Section: Colour-magnitude Diagramsmentioning

confidence: 99%

Section: Distance Via the Red Clump Starsmentioning

confidence: 99%

CCD UBVRI photometry of NGC 6811

Yontan

Bilir

Bostancı

et al. 2015

Astrophys Space Sci

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“…Laney , Joner, & Pietrzyski (2012) determined the absolute magnitude M K s = −1.613 ± 0.015 mag for RC stars in the solar neighbourhood and applied it to estimate the distance of the Large Magellanic Cloud. Karaali, Bilir & Yaz Gökçe (2013) fitted the M K s absolute magnitudes of the RC stars to a linear polynomial in terms of V − K s colour, and Bilir et al (2013a) calibrated the M K s , M V , M J and M g absolute magnitudes in terms of colours corresponding to the photometric systems where the K s , V, J and g bands are defined. Finally, we quote the paper of Bilir et al (2013b) where the M V absolute magnitude had been calibrated in terms of metallicity and B − V colour.…”

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Solar Space Density of the Red Clump Stars and the Scale-Length of the Thin Disc

Gökçe

Karaali

Duran

et al. 2015

Publ. Astron. Soc. Aust.

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We estimated the scale-length of the thin disc with the J and W1 magnitudes of the most probable red clump stars in the Galactic plane, −0• .5 ≤ b ≤ +0• .5, in 19 equal sized fields with consecutive Galactic longitudes which cover the interval 90Our results are constrained with respect to the solar space density (D * = 5.95), which indicates that the radial variation of the density is lower for higher Galactocentric distances. The scale-length of the thin disc is 2 kpc for the fields in the Galactic anticentre direction or close to this direction, while it decreases continuously in the second and third quadrants reaching to a lower limit of h = 1.6 kpc at the Galactic longitudes l = 90• and l = 270• . The distribution of the scale-length in 19 fields is consistent with the predictions from the Galaxia model and its variation with longitude is probably due to the inhomogeneity structure of the disc caused by the accreted material or other features such as warp and flare.

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“…There has been much debate on the nature of the RC stars and their use as a standard candle since their discovery. There are several studies which show that the absolute magnitude of the RC stars in different parts of the electromagnetic spectrum is always the same (Paczynski & Stanek 1998; Keenan & Barnbaum 1999; Alves 2000; Udalski 2000; Groenewegen 2008; Laney, Joner, & Pietrzyński 2012; Bilir et al 2013a, 2013b; Karaali, Bilir, & Yaz Gökçe 2013; Yaz Gökçe et al 2013): Absolute magnitudes of the RC stars are in the near infrared K s band, − 1.54 ± 0.04 mag (Groenewegen 2008), and in I band M I = − 0.23 ± 0.03 mag (Paczynski & Stanek 1998). RC stars are common objects in the Solar neighborhood and their intrinsic brightness probes large distances, which enables us to investigate chemical gradients both in radial and vertical directions.…”

Section: Introductionmentioning

confidence: 99%

Local Stellar Kinematics from RAVE data—VII. Metallicity Gradients from Red Clump Stars

Taş

Bilir

Seabroke

et al. 2016

Publ. Astron. Soc. Aust.

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We investigate the Milky Way Galaxy’s radial and vertical metallicity gradients using a sample of 47 406 red clump stars from the RAdial Velocity Experiment Data Release 4. Distances are calculated by adopting Ks-band absolute magnitude as −1.54±0.04 mag for the sample. The metallicity gradients are calculated with their current orbital positions (Rgc and Z) and with their orbital properties (Rm and zmax): d[Fe/H]/dRgc = −0.047±0.003 dex kpc−1 for |Z| ≤ 0.5 kpc and d[Fe/H]/dRm = −0.025±0.002 dex kpc−1 for zmax ≤ 0.5 kpc. This reaffirms the radial metallicity gradient in the thin disc but highlights that gradients are sensitive to the selection effects caused by the difference between Rgc and Rm. The radial gradient is flat in the distance interval 0.5-1 kpc from the plane and then becomes positive greater than 1 kpc from the plane. The radial metallicity gradients are also eccentricity dependent. We showed that d[Fe/H]/dRm = −0.089±0.010, −0.073±0.007, −0.053±0.004 and −0.044±0.002 dex kpc−1 for ep ≤ 0.05, ep ≤ 0.07, ep ≤ 0.10 and ep ≤ 0.20 sub-samples, respectively, in the distance interval zmax ≤ 0.5 kpc. Similar trend is found for vertical metallicity gradients. Both the radial and vertical metallicity gradients are found to become shallower as the eccentricity of the sample increases. These findings can be used to constrain different formation scenarios of the thick and thin discs.

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Luminosity–colour relations for red clump stars

Cited by 15 publications

References 52 publications

CCD UBVRI photometry of NGC 6811

CCD UBVRI photometry of NGC 6811

Solar Space Density of the Red Clump Stars and the Scale-Length of the Thin Disc

Local Stellar Kinematics from RAVE data—VII. Metallicity Gradients from Red Clump Stars

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