Elemental abundance analyses with DAO spectrograms

Kocer, D.; Adelman, Saul J.; Caliskan, H.; Gulliver, A. F.; Tektunali, H. G.

doi:10.1051/0004-6361:20030620

Cited by 13 publications

(7 citation statements)

References 28 publications

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“…The published abundances of Ba in chemically normal early-type stars (Lemke 1990;Caliskan & Adelman 1997;Adelman 1999;Kocer et al 2003) show a definite trend towards a Ba overabundance. The non-LTE corrections for Ba should be positive, leading to an even greater discrepancy with the solar value, that probably does not represent early-type stars.…”

Section: π Cetmentioning

confidence: 94%

“…Almost nothing is known about non-LTE effects for Sc at these temperatures, so that to understand whether the observed underabundance is real, a non-LTE analysis should be performed. Caliskan & Adelman (1997), Adelman (1998), Adelman (1999), and Kocer et al (2003) have published abundances of several chemically normal, early-type stars. The derived Sc abundance for stars with an effective temperature similar to that of 21 Peg is almost always below the solar value, with nearly solar abundances for other Fe-peak elements.…”

Section: Pegmentioning

confidence: 99%

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The chemical abundance analysis of normal early A- and late B-type stars

Fossati

Ryabchikova

Bagnulo³

et al. 2009

A&A

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Context. Modern spectroscopy of early-type stars often aims at studying complex physical phenomena such as stellar pulsation, the peculiarity of the composition of the photosphere, chemical stratification, the presence of a magnetic field, and its interplay with the stellar atmosphere and the circumstellar environment. Comparatively less attention is paid to identifying and studying the "normal" A-and B-type stars and testing how the basic atomic parameters and standard spectral analysis allow one to fit the observations. By contrast, this kind of study is paramount for eventually allowing one to correctly quantify the impact of the various physical processes that occur inside the atmospheres of A-and B-type stars. Aims. We wish to establish whether the chemical composition of the solar photosphere can be regarded as a reference for early Aand late B-type stars. Methods. We have obtained optical high-resolution, high signal-to-noise ratio spectra of three slowly rotating early-type stars (HD 145788, 21 Peg and π Cet) that show no obvious sign of chemical peculiarity, and performed a very accurate LTE abundance analysis of up to 38 ions of 26 elements (for 21 Peg), using a vast amount of spectral lines visible in the spectral region covered by our spectra. Results. We provide an exhaustive description of the abundance characteristics of the three analysed stars with a critical review of the line parameters used to derive the abundances. We compiled a table of atomic data for more than 1100 measured lines that may be used in the future as a reference. The abundances we obtained for He, C, Al, S, V, Cr, Mn, Fe, Ni, Sr, Y, and Zr are compatible with the solar ones derived with recent 3D radiative-hydrodynamical simulations of the solar photosphere. The abundances of the remaining studied elements show some degree of discrepancy compared to the solar photosphere. Those of N, Na, Mg, Si, Ca, Ti, and Nd may well be ascribed to non-LTE effects; for P, Cl, Sc and Co, non-LTE effects are totally unknown; O, Ne, Ar, and Ba show discrepancies that cannot be ascribed to non-LTE effects. The discrepancies obtained for O (in two stars) and Ne agree with very recent non-LTE abundance analysis of early B-type stars in the solar neighbourhood.

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Section: π Cetmentioning

confidence: 94%

Section: Pegmentioning

confidence: 99%

The chemical abundance analysis of normal early A- and late B-type stars

Fossati

Ryabchikova

Bagnulo³

et al. 2009

A&A

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“…Clearly, up to about 10 500 K abundances increase with temperature, which immediately calls for another investigation: is there a similar trend for normal stars and/or is this trend artificially caused by incorrect model atmospheres and spectrum reduction techniques? For this purpose we compiled Cr and Fe abundances for normal, superficially-normal, Am and δ Scuti-type stars with low rotational velocities (v e sin i < 50 km s −1 ) from papers by Varenne & Monier (1999, Hyades A and F stars), Hill & Landstreet (1993), Mittermayer & Weiss (2003), and from numerous papers by Adelman and co-workers: Adelman (1991, 1994, 1996, Adelman & Davis Philip (1992), Adelman et al (1997Adelman et al ( , 2000Adelman et al ( , 2001, , Adelman & Albayrak (1998), Pintado & Adelman (2003), and Kocer et al (2003).…”

Section: Spectroscopic Signature Of Roap Starsmentioning

confidence: 99%

The spectroscopic signature of roAp stars

Ryabchikova¹,

Nesvacil

Weiß³

et al. 2004

A&A

117

162

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Abstract.To reliably determine the spectroscopic signature of rapidly oscillating chemically peculiar (roAp) stars it is also necessary to investigate a sample of non pulsating chemically peculiar (noAp) as well as presumably "normal" stars. We describe in this study the sample of spectroscopically investigated stars and comment on the techniques used for the analysis. In particular we discuss ionization disequilibria of rare earths in roAp stars that distinguish them from noAp stars. In the light of the recently discovered pulsation of β CrB we see arguments that all magnetic CP2 stars up to a transition temperature of about 8100 K may be pulsating.

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“…Gray's (1992) use of Fourier techniques is very elegant, but requires high signal-to-noise and resolution. I fit clean single metal lines on the linear part of the curve of growth with Gaussian or rotational profiles and correct for the instrumental profile (using, e.g., VLINE (Hill & Fisher 1986)) or synthesize the spectrum, rotate, and convole it with the instrumental profile (with a spectrum synthesis program such as SYNTHE (Kurucz & Avrett 1981). Still the photospheric and outer envelope rotation rates do not necessarily tell us how fast the core rotates as the degree of coupling is uncertain.…”

Section: Properties Of Main Sequence Band Normal a Starsmentioning

confidence: 99%

“…Values are from Adelman (1986Adelman ( , 1987Adelman ( , 1989Adelman ( , 1991Adelman ( , 1999, Adelman & Albayrak (1998), Adelman & Gulliver (1990), Adelman & Philip (1996). Adelman et al (1997Adelman et al ( , 1999Adelman et al ( , 2000Adelman et al ( , 2001, , Kocer et al (2003), and. My conceptual model is that stars rotating sufficiently fast have normal abundances over all of their photospheres.…”

Section: Properties Of Main Sequence Band Normal a Starsmentioning

confidence: 99%

The physical properties of normal A stars

Adelman

2004

Proc. IAU

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Abstract. Designating a star as of A-type is a result of spectral classification. After separating the peculiar stars from those deemed to be normal using the results of a century of stellar astrophysical wisdom, I define the physical properties of the "normal" stars. The hotter A stars have atmospheres almost in radiative equilibrium. In the A stars convective motions can be found which increase in strength as the temperature decreases.

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Elemental abundance analyses with DAO spectrograms

Abstract: Abstract. The superficially normal stars θ And (A2 V), Del (B6 III), Aqr (A1.5 V), and ι And (B9 V), which have rotationally broadened line profiles, are analyzed in a manner consistent with previous studies of this series using 2.4 Å mm

Cited by 13 publications

References 28 publications

The chemical abundance analysis of normal early A- and late B-type stars

The chemical abundance analysis of normal early A- and late B-type stars

The spectroscopic signature of roAp stars

The physical properties of normal A stars

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