The Variability of the Hg<scp>ii</scp>λ3984 Line of the Mercury‐Manganese Star α Andromedae

Adelman, Saul J.; Gulliver, A. F.; Kochukhov, O.; Ryabchikova, T. A.

doi:10.1086/341140

Cited by 82 publications

(100 citation statements)

References 27 publications

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“…As can be seen in Fig. 4, the Ti abundance does not exhibit a distinct ring structure around the stellar equator as was found for the Hg distribution in the HgMn star αAnd (Adelman et al 2002). The maps in general show a surface abundance that is higher than the solar abundance of Ti, −7.02, and have an average abundance of −6.47.…”

Section: Surface Chemical Inhomogeneities By Doppler Imaging Reconstrsupporting

confidence: 59%

“…The first indication of variability of the Hg ii 3984 Å and Y ii 3983 Å lines was reported for the HgMn SB2 system AR Aur by Takeda et al (1979). Later, Wahlgren et al (2001) and Adelman et al (2002) showed that the Hg ii 3984 Å line of the primary component of α And varies with a 2.8-d period. The spectral line variations were attributed to the surface inhomogeneous mercury distribution along the stellar equator, together with the stellar rotation period.…”

Section: Introductionmentioning

confidence: 99%

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Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

Briquet¹,

Korhonen

González

et al. 2010

A&A

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Aims.We gathered about 100 high-resolution spectra of three typical HgMn (mercury-manganese) stars, HD 11753, HD 53244, and HD 221507, to search for slowly pulsating B-like pulsations and surface inhomogeneous distribution of various chemical elements.Methods. Classical frequency analysis methods were used to detect line profile variability and to determine the variation period. Doppler imaging reconstruction was performed to obtain abundance maps of chemical elements on the stellar surface. Results. For HD 11753, which is the star with the most pronounced variability, distinct spectral line profile changes were detected for Ti, Sr, Y, Zr, and Hg, whereas for HD 53244 and HD 221507 the most variable line profiles belong to the elements Hg and Y, respectively. We derived rotation periods for all three stars from the variations of radial velocities and equivalent widths of spectral lines belonging to inhomogeneously distributed elements: P rot (HD 11753) = 9.54 d, P rot (HD 53244) = 6.16 d, and P rot (HD 221507) = 1.93 d. For HD 11753 the Doppler imaging technique was applied to derive the distribution of the most variable elements Ti, Sr, and Y using two datasets separated by ∼65 days. Results of Doppler imaging reconstruction revealed noticeable changes in the surface distributions of Ti ii, Sr ii, and Y ii between the datasets, indicating the hitherto not well understood physical processes in stars with radiative envelopes that cause a rather fast dynamical chemical spot evolution.

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Section: Surface Chemical Inhomogeneities By Doppler Imaging Reconstrsupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

Briquet¹,

Korhonen

González

et al. 2010

A&A

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“…There is not a good explanation of this behavior. Recently, this line's profile in the HgMn star α And A was found to be peculiar (Ryabchikova et al 1999) and later periodically variable (Adelman et al 2002), the first known example of spectral variability among the HgMn stars. The most likely interpretation of this variability is an inhomogeneous Hg surface distribution combined with the 2.382 day stellar rotation period.…”

Section: Discussionmentioning

confidence: 98%

“…For example, exploratory calculations by Seaton (1996) using Opacity Project data suggest that their manganese rich atmospheres are a time variable surface result of radiatively-driven diffusion deep in the stellar envelope. 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%

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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“…HgMn stars are frequently found in binaries and lie on the H-R diagram between the early-A and late-B spectral types, which corresponds to T eff = 9500 − 16000 K. A number of studies during the last decade reported variability of some spectral lines, indicating the presence of chemical spots in HgMn stars (Adelman et al 2002, Kochukhov et al 2005, Hubrig et al 2006. It is believed that the presence of magnetic field is necessary for creating inhomogeneities in stellar atmospheres.…”

Section: Introductionmentioning

confidence: 99%

The search for magnetic fields in mercury-manganese stars

et al. 2010

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Abstract. Mercury-manganese (HgMn) stars were considered to be non-magnetic, showing no evidence of surface spots. However, recent investigations revealed that some stars in this class possess an inhomogeneous distribution of chemical elements on their surfaces. According to our current understanding, the most probable mechanism of spot formation involves magnetic fields. Taking the advantage of a newly-built polarimeter attached to the HARPS spectrometer at the ESO 3.6m-telescope, we performed a high-precision spectropolarimetric survey of a large group of HgMn stars. The main purpose of this study was to find out how typical it is for HgMn stars to have weak magnetic fields. We report no magnetic field detection for any of the studied objects, with a typical precision of the longitudinal field measurements of 10 G and down to 1 Gauss for some of the stars. We conclude that HgMn stars lack large-scale magnetic fields typical of spotted magnetic Ap stars and probably lack any fields capable of creating and sustaining chemical spots. Our study confirms that alongside the magnetically altered atomic diffusion, there must be other structure formation mechanism operating in the atmospheres of late-B main sequence stars.

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The Variability of the Hgiiλ3984 Line of the Mercury‐Manganese Star α Andromedae

Cited by 82 publications

References 27 publications

Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

Dynamical evolution of titanium, strontium, and yttrium spots on the surface of the HgMn star HD 11753

Elemental abundance analyses with DAO spectrograms

The search for magnetic fields in mercury-manganese stars

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