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Mercury-manganese (HgMn) stars have been considered as non-magnetic and non-variable chemically peculiar (CP) stars for a long time. However, recent discoveries of the variability in spectral line profiles have suggested an inhomogeneous…

As a well-established procedure for the vast majority of normal main-sequence stars, determination of atmospheric and stellar parameters turns to be a challenging process in case of magnetic chemically peculiar stars. Inhomogeneous…

太阳与恒星天体物理 · 物理学 2015-06-12 D. Shulyak , T. Ryabchikova , O. Kochukhov

The young, rapidly rotating Bp star HR5624 (HD133880) shows an unusually strong non-sinusoidal variability of its longitudinal magnetic field. This behaviour was previously interpreted as the signature of an exceptionally strong,…

太阳与恒星天体物理 · 物理学 2017-09-06 O. Kochukhov , J. Silvester , J. D. Bailey , J. D. Landstreet , G. A. Wade

We have obtained a UVES spectrum of a slowly rotating strongly magnetic Ap star, HD 144897, that exhibits very large overabundances of rare-earth elements. Here we present a detailed spectral analysis of this object, also taking into…

天体物理学 · 物理学 2009-11-11 T. Ryabchikova , A. Ryabtsev , O. Kochukhov , S. Bagnulo

The combination of photometry, spectroscopy and spectropolarimetry of the chemically peculiar stars often aims to study the complex physical phenomena such as stellar pulsation, chemical inhomogeneity, magnetic field and their interplay…

太阳与恒星天体物理 · 物理学 2017-01-25 Santosh Joshi , Eugene Semenko , A. Moiseeva , Kaushal Sharma , Y. C. Joshi , M. Sachkov , Harinder P. Singh , Yerra Bharat Kumar

The study of chemically peculiar (CP) stars in open clusters provides valuable information about their evolutionary status. Their detection can be performed using the $\Delta a$ photometric system, which maps a characteristic flux…

Magnetic fields influence the formation and evolution of stars and impact the observed stellar properties. Ap stars (magnetic A-type stars) are a prime example of this. Access to precise and accurate determinations of their stellar…

太阳与恒星天体物理 · 物理学 2021-06-23 M. Deal , M. S. Cunha , Z. Keszthelyi , K. Perraut , D. L. Holdsworth

High time resolution spectroscopy of roAp stars at large telescopes has led to a major breakthrough in our understanding of magnetoacoustic pulsations in these interesting objects. New observations have allowed to uncover a number of…

天体物理学 · 物理学 2008-10-09 O. Kochukhov

Differential abundances of C, O, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, and Zr were determined from high signal-to-noise VLT/UVES spectra for 25 turnoff stars with -2.4 < [Fe/H] < -1.3. Effective temperatures were obtained from…

星系天体物理 · 物理学 2026-05-01 Poul Erik Nissen , Anish Amarsi

Measurement of the chemical and isotopic composition of cosmic rays is essential for the precise understanding of their propagation in the galaxy. While the model parameters are mainly determined using the B/C ratio, the study of extended…

高能天体物理现象 · 物理学 2011-01-11 01 Collaboration

I review recent results of the observations of magnetoacoustic p-mode oscillations in roAp stars with the focus on time-resolved spectroscopic studies. Time-series spectroscopy of roAp stars reveals unexpected and diverse pulsational…

天体物理学 · 物理学 2009-11-13 O. Kochukhov

We present the results of speckle interferometric observations of 273 magnetic stars most of which are Ap/Bp type. All observations were made at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences.…

太阳与恒星天体物理 · 物理学 2013-09-05 D. A. Rastegaev , Yu. Yu. Balega , V. V. Dyachenko , A. F. Maksimov , E. V. Malogolovets

The mid-IR spectra of six large, irregular PAHs with formulae (C84H24 - C120H36) have been computed using Density Functional Theory (DFT). Trends in the dominant band positions and intensities are compared to those of large, compact PAHs as…

星系天体物理 · 物理学 2012-08-27 Charles W. Bauschlicher, , Els Peeters , Louis J. Allamandola

We report the results of a coherent study of three chemically anomalous metal-poor ([Fe/H] ~ -2) stars. These objects exhibit unusually low abundances of Mg, Si, Ca (alpha-elements) and Sr, Y, and Ba (neutron-capture elements). Our analyses…

This paper describes a study to deduce fundamental parameters and magnetic field characteristics for all magnetic Ap/Bp stars with in a 100 parsec heliocentric radius volume. This study has allowed for the first time the determination of an…

天体物理学 · 物理学 2007-05-23 J. Power , G. A. Wade , D. A. Hanes , M. Auriere , J. Silvester

We derive the mixture of odd to even barium isotopes in the atmosphere of the metal-poor subgiant HD140283 from the analysis of the Ba II transition at 455.4 nm in a high-resolution high signal-to-noise spectrum of the star. The detailed…

天体物理学 · 物理学 2015-05-13 R. Collet , M. Asplund , P. E. Nissen

The stars of the middle main sequence have relatively quiescent outer layers, and unusual chemical abundance patterns may develop in their atmospheres. The presence of chemical peculiarities reveal the action of such subsurface phenomena as…

太阳与恒星天体物理 · 物理学 2015-06-18 J. D. Bailey , J. D. Landstreet , S. Bagnulo

YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) has favorable macroscopic superconducting properties of $T_\mathrm{c}$ up to 93 K and $H_{c2}$ up to 150 T. However, its nanoscale electronic structure remains mysterious because bulk-like electronic…

The recently discovered magnetic Herbig Ae and Be stars may provide qualitatively new information about the formation and evolution of magnetic Ap and Bp stars. We have performed a detailed investigation of one particularly interesting…

High-resolution (R = 143,000), high signal-to-noise (S/N = 700-1100) Gemini-S bHROS spectra have been analyzed in a search for 6Li in 5 stars which host extrasolar planets. The presence of detectable amounts of 6Li in these mature,…

太阳与恒星天体物理 · 物理学 2011-02-11 L. Ghezzi , K. Cunha , V. V. Smith , S. Margheim , S. Schuler , F. X. de Araújo , R. de la Reza