Elemental abundance analyses with DAO spectrograms

Adelman, Saul J.; Gulliver, A. F.; Rayle, K. E.

doi:10.1051/0004-6361:20010007

Cited by 38 publications

(73 citation statements)

References 43 publications

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“…The effective temperature and gravity were first estimated by using the Strömgren photometry and corrected for CP stars. This estimation presents average dispersions of ∼200 K and ∼0.2 dex for T eff and log g, respectively (Adelman & Rayle 2000;Netopil et al 2008). We estimate similar dispersion values for T eff and log g by achieving the excitation and ionization equilibrium.…”

Section: Abundance Analysessupporting

confidence: 64%

“…Adelman & Rayle (2000) and Netopil et al (2008) derived T eff corrections for the Strömgren and other photometric systems, depending on the chemical peculiarity. For the case of HgMn stars, the T eff directly derived by Strömgren photometry is overestimated, so that a correction is neccessary (Adelman & Rayle 2000;Netopil et al 2008). We corrected the derived values of the HgMn star HD 23950 according to Adelman & Rayle (2000), who found a systematic difference between parameters derived from photometric and spectrophotometric techniques.…”

Section: Atmospheric Parametersmentioning

confidence: 99%

“…For the case of HgMn stars, the T eff directly derived by Strömgren photometry is overestimated, so that a correction is neccessary (Adelman & Rayle 2000;Netopil et al 2008). We corrected the derived values of the HgMn star HD 23950 according to Adelman & Rayle (2000), who found a systematic difference between parameters derived from photometric and spectrophotometric techniques. They suggest a general correction for HgMn stars that closely agrees with those derived by Netopil et al (2008).…”

Section: Atmospheric Parametersmentioning

confidence: 99%

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On the nature of sn stars

Saffe

Levato

2014

A&A

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The sn stars were first discoved by Abt & Levato when studying the spectral types in different open clusters. These stars present sharp Balmer lines, sharp metallic lines (C II, Si II, Ca II, Ti II, Fe II), and broad coreless He I lines. Some of the sn stars seem to be related to CP stars. Initially Abt & Levato proposed a shell-like nature to explain the sn stars, although this scenario was subsequently questioned. There is no general agreement about their origin. We aim to derive abundances for a sample of 9 stars, including sn and non-sn stars, to determine the possible relation between sn and CP stars and compare their chemical abundances. That most sn stars belong to open clusters allows us to search for a possible relation with fundamental parameters, including the age and rotation. We also study the possible contribution of different effects to the broad He I lines observed in these stars, such as Stark broadening and the possible He-stratification. Effective temperature and gravity were estimated by Strömgren photometry and then refined by requiring ionization and excitation equilibrium of Fe lines. We derived the abundances by fitting the observed spectra with synthetic spectra using an iterative procedure with the SYNTHE and ATLAS9 codes. We derived metallic abundances of 23 different chemical elements for 9 stars and obtained low projected rotational velocities for the sn stars in our sample (v sin i up to 69 km s −1 ). We also compared 5 stars that belong to the same cluster (NGC 6475) and show that the sn characteristics appear in the 3 stars with the lower rotational velocity. However, the apparent preference of sn stars for objects with the lower v sin i values should be taken with caution due to the small number of objects studied here. We analysed the photospheric chemical composition of sn stars and show that approximately ∼40% of them display chemical peculiarities (such as He-weak and HgMn stars) within a range of temperature of 10 300 K−14 500 K. However, there are also sn stars with solar or nearly-solar (i.e. non-CP) chemical composition. We have studied the possible contribution of different processes to the broad He I lines present in the sn stars. Although NLTE effects could not be completely ruled out, it seems that NLTE is not directly related to the broad He I profiles observed in the sn stars. The broad-line He I 4026 Å is the clearest example of the sn characteristics in our sample. We succesfully fit this line in 4 out of 7 sn stars by using the appropriate Stark broadening tables, while small differences appear in the other 3 stars. Studying the plots of abundance vs. depth for the He I lines resulted in some sn stars probably being stratified in He. However, a further study of variability in the He I lines would help for determining whether a possible non-uniform He superficial distribution could also play a role in these sn stars. We conclude that the broad He I lines that characterize the sn class could be modelled (at least in some of these stars) by the usual radiati...

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Section: Abundance Analysessupporting

confidence: 64%

Section: Atmospheric Parametersmentioning

confidence: 99%

Section: Atmospheric Parametersmentioning

confidence: 99%

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On the nature of sn stars

Saffe

Levato

2014

A&A

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“…Adelman et al (2002) reported the first spectrum variability in Tables 4-8 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/447/685 this stellar class of Hg II λ3984 in α And A, a discovery whose implications are still just being explored (see, e.g., Kockukhov et al 2005). With results from many stars one can look at the dependences on stellar parameters and make comparisons with theoretical predictions (see, e.g., Adelman et al 2001).…”

Section: Introductionmentioning

confidence: 99%

“…The HgMn star υ Her (HD 144206, HR 5982), spectral type B9 III (Cowley et al 1969), was analyzed by Adelman (1992, Paper X) with coadded photographic plates and by Adelman et al (2001) (Paper XXIV) with S/N ≥ 200 Reticon and CCD spectrograms. υ Her is an example of an Fe and Ni-poor HgMn star.…”

Section: Introductionmentioning

confidence: 99%

Elemental abundance analyses with DAO spectrograms

Adelman

Caliskan

Gulliver

et al. 2006

A&A

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We performed elemental abundances analyses of the mercury-manganese (HgMn) stars 53 Tau, β Tau, and γ Crv consistent with previous studies of similar stars in this series. The derived v sin i values for the last two stars are 59 and 32 km s −1 , respectively, both of which are greater than those of HgMn stars previously studied. For 53 Tau this analysis using selected wavelength regions replaces one performed with coadded photographic spectra. A stricter upper limit is placed on any Hg II λ3984 line. The abundances of β Tau are usually greater than those of γ Crv. But the later star has a Hg II λ3984 line which the former lacks. Our analysis of υ Her, which was performed with spectrograms obtained with CCD detectors, is extended by using additional spectrograms to increase the range of wavelengths covered longward of λ4800. Minor changes in the derived abundances result.

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Elemental abundance analyses with Coudé Echelle spectrograms from the TÜBİTAK National Observatory of Turkey: I. The HgMn stars 11 Per, HR 2801, and ν Cnc

Adelman

Yüce

2010

Astron Nachr

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Using coadded spectrograms taken with the Coudé Echelle Spectrograph (CES) of the 1.50-m Russian-Turkish Telescope of the TÜBİTAK National Observatory (TUG) near Antalya in Turkey, elemental abundance analyses of three HgMn stars 11 Per, HR 2801, and ν Cnc were performed. Comparisons are made with spectra obtained with the long camera of the Dominion Astrophysical Observatory (DAO) coudé spectrograph and its SITe4 CCD. The CES equivalent widths are about 12% larger than that for the DAO long camera. Our first results from TUG data/spectra show that all three stars exhibit the Hg II λ3984 line and somewhat diverse abundance patterns. 11 Per tends to have underabundant light elements with underabundant and overabundant Fe-peak elements. HR 2801 has mostly underabundant elements, with a few elements having solar abundances while N and Mn are overabundant. The coolest star ν Cnc has light elements having mostly solar abundances, overabundant iron group abundances, and very overabundant SrYZr and Ba. Comparisons with the abundance patterns of other HgMn stars show that they have a wide diversity of abundance patterns.

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Elemental abundance analyses with DAO spectrograms

Cited by 38 publications

References 43 publications

On the nature of sn stars

On the nature of sn stars

Elemental abundance analyses with DAO spectrograms

Elemental abundance analyses with Coudé Echelle spectrograms from the TÜBİTAK National Observatory of Turkey: I. The HgMn stars 11 Per, HR 2801, and ν Cnc

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