Galactic model parameters for field giants separated from field dwarfs by their 2MASS and <i>V</i> apparent magnitudes

Bilir, S.; Karaali, S.; Güver, T.; Karataş, Yüksel; Ak, S.

doi:10.1002/asna.200510480

Cited by 28 publications

(53 citation statements)

References 36 publications

(60 reference statements)

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“…Effective temperatures were calculated from the empirical calibration of Ramírez & Meléndez (2005), based on Tycho and 2MASS photometry. Rough estimates of log g were obtained using the results of Bilir et al (2006) and Gelino et al (2005). For all these stars, the average value of [Fe/H] obtained for the 332 stars with complete spectroscopic analysis, [Fe/H] = −0.15, was assumed (bottom part of Table 5).…”

Section: Stars With Incomplete Datamentioning

confidence: 99%

The Penn State-Toruń Centre for Astronomy Planet Search stars

Zieliński

Niedzielski

Wolszczan

et al. 2012

A&A

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Aims. We present basic atmospheric parameters (T eff , log g, v t , and [Fe/H]) as well as luminosities, masses, radii, and absolute radial velocities for 348 stars, presumably giants, from the ∼1000 star sample observed within the Penn State-Toruń Centre for Astronomy Planet Search with the High Resolution Spectrograph of the 9.2 m Hobby-Eberly Telescope. The stellar parameters (luminosities, masses, radii) are key to properly interpreting newly discovered low-mass companions, while a systematic study of the complete sample will create a basis for future statistical considerations concerning the appearance of low-mass companions around evolved low-and intermediate-mass stars. Methods. The atmospheric parameters were derived using a strictly spectroscopic method based on the LTE analysis of equivalent widths of Fe I and Fe II lines. With existing photometric data and the Hipparcos parallaxes, we estimated stellar masses and ages via evolutionary tracks fitting. The stellar radii were calculated from either estimated masses and the spectroscopic log g or from the spectroscopic T eff and estimated luminosities. The absolute radial velocities were obtained by cross-correlating spectra with a numerical template. Results. We completed the spectroscopic analysis for 332 stars, 327 of which were found to be giants. A simplified analysis was applied to the remaining 16 stars, which had incomplete data. The results show that our sample is composed of stars with effective temperatures ranging from 4055 K to 6239 K, with log g between 1.39 and 4.78 (5 dwarfs were identified). The estimated luminosities are between log L/L = −1.0 and 3 and lead to masses ranging from 0.6 to 3.4 M . Only 63 stars with masses larger than 2 M were found. The radii of our stars range from 0.6 to 52 R with the vast majority between 9−11 R . The stars in our sample are generally less metal-abundant than the Sun with median [Fe/H] = −0.15. The estimated uncertainties in the atmospheric parameters were found to be comparable to those reached in other studies. However, due to lack of precise parallaxes, the stellar luminosities and, in turn, the masses are far less precise, within 0.2 M in best cases and 0.3 M on average.

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Section: Stars With Incomplete Datamentioning

confidence: 99%

The Penn State-Toruń Centre for Astronomy Planet Search stars

Zieliński

Niedzielski

Wolszczan

et al. 2012

A&A

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“…Then, we plotted them onto the V 0 − J 0 two magnitude diagram ( Fig. 13) and separated the giants (RC stars) from the dwarfs by the procedure of Bilir et al (2006a). It turned out that 101 stars were classified as RC stars.…”

Section: Johnson-cousinsmentioning

confidence: 99%

Luminosity–colour relations for red clump stars

Bilir

Önal

Karaali

et al. 2013

Astrophys Space Sci

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We calibrated the M V , M J , M Ks and M g absolute magnitudes of red clump stars in terms of colours. M V and M g are strongly dependent on colour, while the dependence of M J and M Ks on colour is rather weak. The calibration of M V and M Ks absolute magnitudes is tested on 101 RC stars in the field SA 141. The Galactic model parameters estimated with this sample are in good agreement with earlier studies.

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“…We adopted a mean absolute magnitude M g = 1.5 for giants and we calculated their corresponding distance from the Galactic plane, z = 4.5 kpc, for g 0 = 15. We used the local space density D * = 6.35 and the scaleheight (H = 650 pc) for the thick disc dwarfs and we compared the corresponding space density with that of thick disc giants for local space density D * = 5.58 and the scaleheight (H = 585 pc) adopted from Bilir et al (2006c). It turned out that the number of thick disc giants fainter than g 0 = 15 mag is less than 8% of the number of dwarfs.…”

Section: Figurementioning

confidence: 99%

Estimation of Galactic Model Parameters in High Latitudes with SDSS

Bilir

Cabrera-Lavers

Karaali

et al. 2008

Publ. – Astron. Soc. Aust

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Abstract:We estimated the Galactic model parameters for a set of 36 high-latitude fields included in the currently available Data Release 5 (DR 5) of the Sloan Digital Sky Survey (SDSS), to explore their possible variation with the Galactic longitude. The thick disc scaleheight moves from ∼550 pc at 120 < l < 150 • to ∼720 pc at 250 < l < 290 • , while the thin disc scaleheight is as large as ∼195 pc in the anticenter direction and ∼15% lower at |l| < 30 • . Finally, the axis ratio (c/a) of the halo changes from a mean value of ∼0.55 in the two first quadrants of the Galaxy to ∼0.70 at 190 < l < 300 • . For the halo, the reason for the dependence of the model parameters on the Galactic longitude arises from the well known asymmetric structure of this component. However, the variation of the model parameters of the thin and thick discs with Galactic longitude originates from the gravitational effect of the Galactic long bar. Moreover, the excess of stars in quadrant I (quadrant III) over quadrant IV (quadrant II) is in agreement with this scenario.

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Galactic model parameters for field giants separated from field dwarfs by their 2MASS and V apparent magnitudes

Cited by 28 publications

References 36 publications

The Penn State-Toruń Centre for Astronomy Planet Search stars

The Penn State-Toruń Centre for Astronomy Planet Search stars

Luminosity–colour relations for red clump stars

Estimation of Galactic Model Parameters in High Latitudes with SDSS

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