Semiregular Variables in the Galactic Bulge

Schultheis, M.; Ng, Y. K.; Hron, J.; Habing, H. J.

doi:10.1007/978-94-009-1687-6_47

Cited by 8 publications

(23 citation statements)

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“…The bolometric magnitudes of the Tc-rich as well as of the Li-rich stars identified in these papers are altered by only a few 0. m 01 at most. The biggest consequence is that several sample stars turn out to be bluer in (J − K) 0 after this correction, and the isochrone with 5 Gyr age and solar metallicity of Girardi et al (2000) now well describes the observed colour range when using our (J − K) 0 vs. T eff calibration (see Schultheis et al 1998). Nevertheless, the observed AGB tip luminosity is higher than that of the isochrones from Girardi et al (2000).…”

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confidence: 58%

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Technetium and lithium in Galactic bulge AGB stars

Uttenthaler

Hron

Lebzelter

et al. 2007

A&A

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The near-IR photometry of bulge AGB variables analysed in Uttenthaler et al. (2007a) and Uttenthaler et al. (2007b) was de-reddened incorrectly, because of erroneous galactic latitudes used. Table 1 reproduces the corrected mean J 0 and K 0 magnitudes of the stars.When using the thus corrected values, one star (M 1313) appears as strong outlier in the CMD with a (J − K) 0 colour of 1.61. For this star, ESO near-IR photometry has been acquired at two epochs (Schultheis et al. 1998). Using the ESO photometry only, M 1313 would have (J − K) 0 = 1.71. We suspect that the ESO photometry of M 1313 is in error, too. We thus quote the J 0 and K 0 magnitudes based on the 2MASS measurement only, which yields (J − K) 0 = 1.47.We want to note that five out of 27 spectroscopically confirmed oxygen-rich sample stars have a (J − K) 0 colour redder than the commonly used limit between oxygen-rich M-type and carbon-rich C-type stars of 1.4 (Battinelli et al. 2007).The main conclusions drawn in Uttenthaler et al. (2007a) and Uttenthaler et al. (2007b) remain unaltered. The bolometric magnitudes of the Tc-rich as well as of the Li-rich stars identified in these papers are altered by only a few 0. m 01 at most. The biggest consequence is that several sample stars turn out to be bluer in (J − K) 0 after this correction, and the isochrone with 5 Gyr age and solar metallicity of Girardi et al. (2000) now well describes the observed colour range when using our (J − K) 0 vs. T eff calibration (see Schultheis et al. 1998). Nevertheless, the observed AGB tip luminosity is higher than that of the isochrones from Girardi et al. (2000).

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confidence: 58%

“…For this star, ESO near-IR photometry has been acquired at two epochs (Schultheis et al 1998). Using the ESO photometry only, M 1313 would have (J − K) 0 = 1.71.…”

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confidence: 99%

Technetium and lithium in Galactic bulge AGB stars

Uttenthaler

Hron

Lebzelter

et al. 2007

A&A

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“…The chosen targets were allowed to have a (J−K) 0 colour either bracketed by the isochrones, or 0. m 02 redder or bluer than these. We dereddened the stars using the linear relation for the reddening in the B J photographic band as a function of galactic latitude given in Schultheis et al (1998). To translate this into the extinction in the J-and K-bands, we used the relation R = A V /E(B − V) with R = 3.2 and the reddening law of Glass & Schultheis (2003).…”

Section: Target Selectionmentioning

confidence: 99%

Lithium abundances along the red giant branch: FLAMES-GIRAFFE spectra of a large sample of low-mass bulge stars

Lebzelter

Uttenthaler

Busso

et al. 2012

A&A

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Context. A small number of K-type giants on the red giant branch (RGB) is known to be very rich in lithium (Li). This fact is not accounted for by standard stellar evolution theory. The exact phase and mechanism of Li enrichment is still a matter of debate. Aims. Our goal is to probe the abundance of Li along the RGB, from its base to the tip, to confine Li-rich phases that are supposed to occur on the RGB. Methods. For this end, we obtained medium-resolution spectra with the FLAMES spectrograph at the VLT in GIRAFFE mode for a large sample of 401 low-mass RGB stars located in the Galactic bulge. The Li abundance was measured in the stars with a detectable Li 670.8 nm line by means of spectral synthesis with COMARCS model atmospheres. A new 2MASS (J − K S ) − T eff calibration from COMARCS models is presented in the Appendix. Results. Thirty-one stars with a detectable Li line were identified, three of which are Li-rich according to the usual criterion (log (Li) > 1.5). The stars are distributed all along the RGB, not concentrated in any particular phase of the red giant evolution (e.g. the luminosity bump or the red clump). The three Li-rich stars are clearly brighter than the luminosity bump and red clump, and do not show any signs of enhanced mass loss. Conclusions. We conclude that the Li enrichment mechanism cannot be restricted to a clearly defined phase of the RGB evolution of low-mass stars (M ∼ 1 M ), contrary to earlier suggestions from disk field stars.

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“…5), with respect to the reference K s0 vs (J-K s ) 0 of Bertelli et al (1994) with Z=0.02 and a distance modulus of 14.5 (distance to the Galactic Center : 8 kpc). The near-infrared colours of this isochrone have been computed with an empirical T eff -(J-K) 0 colour relation built by making a fit through measurements for cool giants (see Schultheis et al 1998;. We have assumed that A J /A V = 0.256; A Ks /A V = 0.089 .…”

Section: Interstellar Extinctionmentioning

confidence: 99%

Stellar Sources in the Isogal Intermediate Bulge Fields

Ojha

Omont

Schüller

et al. 2003

Astrophysics and Space Science Library

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Abstract. We present a study of ISOGAL sources in the "intermediate" galactic bulge (|l| < 2 • , |b| ∼ 1 • -4 • ), observed by ISOCAM at 7 and 15 µm. In combination with near-infrared (I, J, K s ) data of DENIS survey, complemented by 2MASS data, we discuss the nature of the ISOGAL sources, their luminosities, the interstellar extinction and the mass-loss rates. A large fraction of the 1464 detected sources at 15 µm are AGB stars above the RGB tip, a number of them show an excess in ([7]

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Semiregular Variables in the Galactic Bulge

Cited by 8 publications

References 1 publication

Technetium and lithium in Galactic bulge AGB stars

Technetium and lithium in Galactic bulge AGB stars

Lithium abundances along the red giant branch: FLAMES-GIRAFFE spectra of a large sample of low-mass bulge stars

Stellar Sources in the Isogal Intermediate Bulge Fields

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