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Exoplanets have sparked interest in extremely high signal-to-noise ratio spectroscopic observations of very bright stars, in a regime where flux calibrators, in particular DA white dwarfs, are not available. We argue that A-type stars offer…

Solar and Stellar Astrophysics · Physics 2015-12-09 Carlos Allende Prieto , Carlos del Burgo

Model stellar atmospheres are fundamental tools for understanding stellar observations from interferometry, microlensing, eclipsing binaries and planetary transits. However, the calculations also include assumptions, such as the geometry of…

Solar and Stellar Astrophysics · Physics 2015-06-15 Hilding R. Neilson , John B. Lester

We present the first parallax and luminosity measurements for an L subdwarf, the sdL7 2MASS J05325346+8246465. Observations conducted over three years by the USNO infrared astrometry program yield an astrometric distance of 26.7+/-1.2 pc…

We have obtained high-resolution spectroscopy, optical interferometry, and long-term broad band photometry of the ellipsoidal primary of the RS CVn-type binary system zeta And. Based on the optical interferometry the apparent limb darkened…

Solar and Stellar Astrophysics · Physics 2015-05-18 H. Korhonen , M. Wittkowski , Zs. Kovari , Th. Granzer , T. Hackman , K. G. Strassmeier

Radio continuum and polarization observations of the entire Cygnus Loop at 6cm wavelength were made with the Urumqi 25m telescope. The 6cm map is analysed together with recently published maps from the Effelsberg 100m telescope at 21cm and…

Astrophysics · Physics 2009-11-11 X. H. Sun , W. Reich , J. L. Han , P. Reich , R. Wielebinski

New angular diameter determinations for the bright southern F8 supergiant Delta CMa enable the bolometric emergent flux and effective temperature of the star to be determined with improved accuracy. The spectral flux distribution and…

The Herbig Ae/Be star LkHalpha 101 has been imaged at high angular resolution at a number of wavelengths in the near-infrared (from 1 to 3 microns) using the Keck 1 Telescope, and also observed in the mid-infrared (11.15 microns) using the…

Astrophysics · Physics 2009-11-07 P. G. Tuthill , J. D. Monnier , W. C. Danchi , D. D. S. Hale , C. H. Townes

The number of stellar angular diameter measurements has greatly increased over the past few years due to innovations and developments in the field of long baseline optical interferometry (LBOI). We use a collection of high-precision angular…

Solar and Stellar Astrophysics · Physics 2015-06-17 Tabetha Boyajian , Gerard van Belle , Kaspar von Braun

We present high-contrast angular differential imaging (ADI) observations of the debris disk around HD 32297 in H-band, as well as the first polarimetric images for this system in polarized differential imaging (PDI) mode with Subaru/HICIAO.…

We have executed a survey of nearby, main sequence A, F, and G-type stars with the CHARA Array, successfully measuring the angular diameters of fortyfour stars with an average precision of ~ 1.5%. We present new measures of the bolometric…

We present new or updated angular diameters, physical radii, and effective temperatures for 145 stars from the Navy Precision Optical Interferometer data archive. We used data from 1996 to late-2021, and we describe the differences between…

Solar and Stellar Astrophysics · Physics 2025-06-04 Ellyn K. Baines , James H. Clark , Bradley I. Kingsley , Henrique R. Schmitt , Jordan M. Stone

HST/NICMOS PSF-subtracted coronagraphic observations of HD 181327 have revealed the presence of a ring-like disk of circumstellar debris seen in 1.1 micron light scattered by the disk grains, surrounded by a di use outer region of lower…

We present the first high spatial and spectral observations of the circumstellar envelope (CSE) of a B[e] supergiant (CPD$-57 2874$), performed with the Very Large Telescope Interferometer (VLTI). Spectra, visibilities, and closure phase,…

Microturbulence (\xi) is a key parameter introduced in stellar spectroscopy to explain the strength of saturated lines by formally incorporating an additional thermal broadening term in the line opacity profile. Although our Sun can serve…

Solar and Stellar Astrophysics · Physics 2022-01-12 Yoichi Takeda

We report the detection of both the 67.9 and 78.4 keV 44Sc gamma-ray lines in Cassiopeia A with the INTEGRAL IBIS/ISGRI instrument. Besides the robustness provided by spectro-imaging observations, the main improvements compared to previous…

We find the angular diameter of R Doradus to be 57 +/- 5 mas, exceeding that of Betelgeuse and implying that R Dor is larger in apparent size than every star except the Sun. R Dor is shown to be closely related to the Mira variables. We…

We present direct measurements of the limb-darkened intensity profiles of the late-type giant stars HR5299, HR7635, and HR8621 obtained with the Navy Prototype Optical Interferometer (NPOI) at the Lowell Observatory. A triangle of baselines…

Astrophysics · Physics 2009-11-07 M. Wittkowski , C. A. Hummel , K. J. Johnston , D. Mozurkewich , A. R. Hajian , N. M. White

We have commenced a 21-cm survey of the entire southern sky (\delta < 0 degrees, -1200 km/s < v < 12700 km/s) which is ''blind'', i.e. unbiased by previous optical information. In the present paper we report on the results of a pilot…

We report the discovery of Corvus A, a low-mass, gas-rich galaxy at a distance of approximately 3.5 Mpc, identified in DR10 of the Dark Energy Camera Legacy Imaging Survey during the initial phase of our ongoing SEmi-Automated Machine…

We present new high-resolution observations of Sagittarius A* at wavelengths of 17.4 to 23.8 cm with the Very Large Array in A configuration with the Pie Town Very Long Baseline Array antenna. We use the measured sizes to calibrate the…

Astrophysics · Physics 2011-02-11 Geoffrey C. Bower , W. M. Goss , Heino Falcke , Donald C. Backer , Yoram Lithwick
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