Local stellar kinematics from RAVE data - II. Radial metallicity gradient

Coşkunoğlu, B.; Ak, S.; Bilir, S.; Karaali, S.; Önal, Ö.; Yaz, E.; Gilmore, G.; Seabroke, G. M.

doi:10.1111/j.1365-2966.2011.19925.x

Cited by 48 publications

(50 citation statements)

References 50 publications

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“…The orbital elements for a star used in our work are the mean of the corresponding orbital elements calculated over 15 orbital periods of that specific star. The orbital integration typically corresponds to 3 Gyr and is sufficient to evaluate the orbital elements of solar suburb stars (Coşkunoglu et al 2012;Bilir et al 2012;Duran et al 2013). Table 1.…”

Section: Local Stellar Kinematics From Rave Data -V Kinematic Investmentioning

confidence: 99%

Local Stellar Kinematics from RAVE data – V. Kinematic Investigation of the Galaxy with Red Clump Stars

Karaali

Bilir

et al. 2014

Publ. Astron. Soc. Aust.

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We investigated the space velocity components of 6 610 red clump (RC) stars in terms of vertical distance, Galactocentric radial distance and Galactic longitude. Stellar velocity vectors are corrected for differential rotation of the Galaxy which is taken into account using photometric distances of RC stars. The space velocity components estimated for the sample stars above and below the Galactic plane are compatible only for the space velocity component in the direction to the Galactic rotation of the thin disc stars. The space velocity component in the direction to the Galactic rotation (V lsr ) shows a smooth variation relative to the mean Galactocentric radial distance (R m ), while it attains its maximum at the Galactic plane. The space velocity components in the direction to the Galactic centre (U lsr ) and in the vertical direction (W lsr ) show almost flat distributions relative to R m , with small changes in their trends at R m ∼ 7.5 kpc. U lsr values estimated for the RC stars in quadrant 180 • < l ≤ 270 • are larger than the ones in quadrants 0 • < l ≤ 90 • and 270 • < l ≤ 360 • . The smooth distribution of the space velocity dispersions reveals that the thin and thick discs are kinematically continuous components of the Galaxy. Based on the W lsr space velocity components estimated in the quadrants 0 • < l ≤ 90 • and 270 • < l ≤ 360 • , in the inward direction relative to the Sun, we showed that RC stars above the Galactic plane move towards the North Galactic Pole, whereas those below the Galactic plane move in the opposite direction. In the case of quadrant 180 • < l ≤ 270 • , their behaviour is different, i.e. the RC stars above and below the Galactic plane move towards the Galactic plane. We stated that the Galactic long bar is the probable origin of many, but not all, of the detected features.

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Section: Local Stellar Kinematics From Rave Data -V Kinematic Investmentioning

confidence: 99%

Local Stellar Kinematics from RAVE data – V. Kinematic Investigation of the Galaxy with Red Clump Stars

Karaali

Bilir

et al. 2014

Publ. Astron. Soc. Aust.

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“…The full set of RAVE chemo-kinematical data was recently used by Boeche et al (2013) to study the relation between abundances and kinematics of the Galactic disc populations. The radial metallicity gradient was previously studied in recent works by using RAVE data (Karataş & Klement 2012;Coşkunoǧlu et al 2012), but none of them investigated the gradients for the individual elemental abundances. Recently, Bilir et al (2012) split a sample of red-clump RAVE stars into thin-and thick-disc subsamples by labelling the stars as a function of their kinematic characteristics, and measured the metallicity gradients in these subsamples.…”

Section: Introductionmentioning

confidence: 99%

“…The chemical gradients found by previous investigations can span quite a wide range (from −0.029 dex kpc −1 by Andrievsky et al 2002 using Cepheids, to −0.17 dex kpc −1 by Sestito et al 2008 using open clusters). Most of the works seem to converge on a value close to ∼−0.06 dex kpc −1 by using different tracers (Cepheids by Luck et al 2006;Luck & Lambert 2011;Yong et al 2006;Lemasle et al 2008 among others; open clusters by Friel et al 2002;Sestito et al 2008;Pancino et al 2010 among others; planetary nebulae by Pasquali & Perinotto 1993;Maciel & Quireza 1999; main-sequence turn-off stars by Cheng et al 2012;Coşkunoǧlu et al 2012). It has been shown that the radial gradient becomes flatter with increasing distance from the Galactic plane (Pasquali & Perinotto 1993;Boeche 2011;Cheng et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Chemical gradients in the Milky Way from the RAVE data

Boeche

Siebert

Piffl

et al. 2013

A&A

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Aims. We aim at measuring the chemical gradients of the elements Mg, Al, Si, and Fe along the Galactic radius to provide new constraints on the chemical evolution models of the Galaxy and Galaxy models such as the Besançon model. Thanks to the large number of stars of our RAVE sample we can study how the gradients vary as function of the distance from the Galactic plane. Methods. We analysed three different samples selected from three independent datasets: a sample of 19 962 dwarf stars selected from the RAVE database, a sample of 10 616 dwarf stars selected from the Geneva-Copenhagen Survey (GCS) dataset, and a mock sample (equivalent to the RAVE sample) created by using the GALAXIA code, which is based on the Besançon model. The three samples were analysed by using the very same method for comparison purposes. We integrated the Galactic orbits and obtained the guiding radii (R g ) and the maximum distances from the Galactic plane reached by the stars along their orbits (Z max ). We measured the chemical gradients as functions of R g at different Z max . Results. We found that the chemical gradients of the RAVE and GCS samples are negative and show consistent trends, although they are not equal: at Z max < 0.4 kpc and 4.5 < R g (kpc) < 9.5, the iron gradient for the RAVE sample is d[Fe/H]/dR g = −0.065 dex kpc −1 , whereas for the GCS sample it is d[Fe/H]/dR g = −0.043 dex kpc −1 with internal errors of ±0.002 and ±0.004 dex kpc −1 , respectively. The gradients of the RAVE and GCS samples become flatter at larger Z max . Conversely, the mock sample has a positive iron gradient of d[Fe/H]/dR g = +0.053 ± 0.003 dex kpc −1 at Z max < 0.4 kpc and remains positive at any Z max . These positive and unrealistic values originate from the lack of correlation between metallicity and tangential velocity in the Besançon model. In addition, the low metallicity and asymmetric drift of the thick disc causes a shift of the stars towards lower R g and metallicity which, together with the thin-disc stars with a higher metallicity and R g , generates a fictitious positive gradient of the full sample. The flatter gradient at larger Z max found in the RAVE and the GCS samples may therefore be due to the superposition of thin-and thick-disc stars, which mimicks a flatter or positive gradient. This does not exclude the possibility that the thick disc has no chemical gradient. The discrepancies between the observational samples and the mock sample can be reduced by i) decreasing the density; ii) decreasing the vertical velocity; and iii) increasing the metallicity of the thick disc in the Besançon model.

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“…A good representation of the Milky Way is obtained with the superposition of these components. The orbital period of the LSR is taken P = 2.18 × 10 8 years while V c = 222.5 km s −1 represents the circular rotational velocity at the Solar Galactocentric distance, R 0 = 8 kpc (Coşkunoglu et al 2012;Bilir et al 2012). …”

Section: Population Analysismentioning

confidence: 99%

The Galactic kinematics of cataclysmic variables

Bilir

Özdönmez

et al. 2015

Astrophys Space Sci

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Kinematical properties of CVs were investigated according to population types and orbital periods, using the space velocities computed from recently updated systemic velocities, proper motions and parallaxes. Reliability of collected space velocity data are refined by removing 34 systems with largest space velocity errors. The 216 CVs in the refined sample were shown to have a dispersion of 53.70 ± 7.41 km s −1 corresponding to a mean kinematical age of 5.29 ± 1.35 Gyr. Population types of CVs were identified using their Galactic orbital parameters. According to the population analysis, seven old thin disc, nine thick disc and one halo CV were found in the sample, indicating that 94% of CVs in the Solar Neighbourhood belong to the thindisc component of the Galaxy. Mean kinematical ages 3.40±1.03 and 3.90±1.28 Gyr are for the non-magnetic thin-disc CVs below and above the period gap, respectively. There is not a meaningful difference between the velocity dispersions below and above the gap. Velocity dispersions of the non-magnetic thin-disc systems below and above the gap are 24.95 ± 3.46 and 26.60 ± 4.18 km s −1 , respectively. This result is not in agreement with the standard formation and evolution theory of CVs. The mean kinematical ages of the CV groups in various orbital period intervals increase towards shorter orbital periods. This is in agreement with the standard theory for the evolution of CVs. Rate of orbital period change was found to be dP/dt = −1.62(±0.15) × 10 −5 sec yr −1 .

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Local stellar kinematics from RAVE data - II. Radial metallicity gradient

Cited by 48 publications

References 50 publications

Local Stellar Kinematics from RAVE data – V. Kinematic Investigation of the Galaxy with Red Clump Stars

Local Stellar Kinematics from RAVE data – V. Kinematic Investigation of the Galaxy with Red Clump Stars

Chemical gradients in the Milky Way from the RAVE data

The Galactic kinematics of cataclysmic variables

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