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Recently we have demonstrated that high-precision polarization observations can detect the polarization resulting from the rotational distortion of a rapidly rotating B-type star. Here we investigate the extension of this approach to an…

Solar and Stellar Astrophysics · Physics 2020-04-01 Jeremy Bailey , Daniel V. Cotton , Ian D. Howarth , Fiona Lewis , Lucyna Kedziora-Chudczer

Projected rotational velocities (vsini) are presented for a sample of 350 early B-type main sequence stars in the nearby Galactic disk. The stars are located within ~1.5 kpc from the Sun, and the great majority within 700 pc. The analysis…

Solar and Stellar Astrophysics · Physics 2012-10-03 G. A. Bragança , S. Daflon , K. Cunha , T. Bensby , M. S. Oey , G. Walth

Spatially resolving the surfaces of nearby stars promises to advance our knowledge of stellar physics. Using optical long-baseline interferometry, we present here a near-infrared image of the rapidly rotating hot star Altair with <1…

We present an analysis of observations of the bright star Altair (alpha Aql) obtained using the star camera on the Wide-Field Infrared Explorer (WIRE) satellite. Although Altair lies within the delta Scuti instability strip, previous…

We derive projected rotational velocities (vsini) for a sample of 156 Galactic OB star members of 35 clusters, HII regions, and associations. The HeI lines at $\lambda\lambda$4026, 4388, and 4471A were analyzed in order to define a…

Astrophysics · Physics 2009-06-23 S. Daflon , K. Cunha , F. X. de Araujo , S. Wolff , N. Przybilla

Be stars are found to rotate close to their critical rotation and therefore they are considered as an important laboratory of study for stellar rotation. In this context, we obtain the projected rotational velocity of a sample of classical…

Solar and Stellar Astrophysics · Physics 2022-01-28 Martín Solar , Catalina Arcos , Michel Curé , Ronaldo S. Levenhagen , Ignacio Araya

The present paper describes the first results of an observational program intended to refine and extend the existing vsini measurements of metal-poor stars, with anemphasis on field evolved stars. The survey was carried out with the FEROS…

We present observations of the A7IV-V star Alderamin ($\alpha$ Cep, HR 8162, HD 203280) from the Georgia State University CHARA Array. These infrared interferometric angular size measurements indicate a non-circular projected disk…

Previous investigations on hydrogen-rich white dwarfs generally yield only very small rotational velocities (v_rot sin i). We have analyzed line profiles in high-resolution optical spectra of eight hydrogen-deficient (pre-) white dwarfs and…

Astrophysics · Physics 2007-05-23 T. Rauch , S. Koeper , S. Dreizler , K. Werner , U. Heber , I. N. Reid

Stellar rotation influences our understanding of stellar structure and evolution, binary systems, clusters etc. and therefore the benefits of a large and highly accurate database on stellar rotation, obtained by GAIA, will be manifold. To…

Astrophysics · Physics 2007-05-23 Andreja Gomboc

We report detection of differential rotation on the F5 dwarf psi Cap using line profile analysis. The Fourier transform of both FeI lambda 5775 and SiI lambda 5772 are used to obtain a projected rotational velocity of v sini = (42+-1)km/s.…

Astrophysics · Physics 2009-11-06 A. Reiners , J. H. M. M. Schmitt , M. Kuerster

Measuring stellar rotational velocities is a powerful way to probe the many astrophysical phenomena that drive, or are driven by, the evolution of stellar angular momentum. In this paper, we present a novel data-driven approach to measuring…

Solar and Stellar Astrophysics · Physics 2019-04-17 Steven Gilhool , Cullen Blake

Based on the high resolution spectral monitoring conducted at the 6-m BTA telescope, we study the optical spectrum of the high-latitude variable V534 Lyr. Heliocentric radial velocities Vr corresponding to the positions of all metal…

Solar and Stellar Astrophysics · Physics 2018-04-04 V. G. Klochkova , E. G. Sendzikas , E. L. Chentsov

Rotational curves are measured for almost complete sample of 308 northern spiral galaxies using the 6-m telescope. For observations we selected edge-on galaxies from RFGC catalog with apparent axial ratio a/b>8, angular diameter a<2', and…

Astrophysics · Physics 2007-05-23 D. I. Makarov , I. D. Karachentsev , A. N. Burenkov

The projected stellar rotational velocity ($v \sin i$) is critical for our understanding of processes related to the evolution of angular momentum in pre-main sequence stars. We present $v \sin i$ measurements of high-resolution infrared…

We have studied variability of the spectral lines of the OB star $\delta $Ori A--the brightest component of the $\delta $Ori triple system. Forty spectra with signal-to-noise ratios $\approx$500--800 and a time resolution of four minutes…

Astrophysics · Physics 2009-11-11 A. F. Kholtygin , T. E. Burlakova , S. N. Fabrika , G. G. Valyavin , M. V. Yushkin

The radio spectra of main-sequence stars remain largely unconstrained due to the lack of observational data to inform stellar atmosphere models. As such, the dominant emission mechanisms at long wavelengths, how they vary with spectral…

Since solar-like oscillations were first detected in red-giant stars, the presence of non-radial oscillation modes has been debated. Spectroscopic line-profile analysis was used in the first attempt to perform mode identification, which…

Solar and Stellar Astrophysics · Physics 2015-05-18 S. Hekker , C. Aerts

Context: Rotation plays a key role in the life cycles of stars with masses above 8 Msun. Hence, accurate knowledge of the rotation rates of such massive stars is critical for understanding their properties and for constraining models of…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. O. Sundqvist , S. Simon-Diaz , J. Puls , N. Markova

We present measurements of the projected stellar rotation velocities (v sin i) of a sample of 45 candidate field horizontal-branch (HB) stars spanning a wide range of effective temperature, from red HB stars with Teff ~ 5000 K to blue HB…

Astrophysics · Physics 2009-11-10 Bradford B. Behr