A Study of the Angular Diameters of Dust Shells Around Red Giants

1991 ◽  
Author(s):  
H. M. Dyck ◽  
J. A. Benson
Keyword(s):  
Red Giants ◽  
Dust Shells ◽  
Angular Diameters

scholarly journals Interferometry of pulsating red giants from 0.65 to 3.5 microns

2004 ◽  
Vol 193 ◽  
pp. 327-331 ◽  
Author(s):  
Michael Ireland ◽  
Peter Tuthill ◽  
Gordon Robertson ◽  
Timothy Bedding ◽  
Andrew Jacob ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Wavelength Region ◽  
Red Giants ◽  
Multi Wavelength ◽  
Angular Diameters

AbstractWe present the results of two multi-wavelength studies of the angular diameters of the Mira-like stars ο Cet, W Hya and R Leo. The MAPPIT experiment was able to deliver diameters of these stars over a continuous wavelength region from 0.65 – 1 micron, while the Keck aperture-masking experiment was able to deliver diameters between 1.2 and 3.5 microns. Strong size variations with wavelength were recorded for all stars, and we discuss the implications for model atmospheres of these stars, and speculate on the necessity of including dust scattering in radiative transfer calculations.

scholarly journals Angular Diameters of the Red Giants 46 Leo and φ Aqr and Parameters of some Binary Systems from Occultation Observations

1971 ◽  
Vol 2 ◽  
pp. 692-699
Author(s):  
Howard L. Poss
Keyword(s):  
Binary Systems ◽  
Red Giants ◽  
Visual Binary ◽  
Angular Diameters

AbstractAngular diameters of 0″.0056 ± 0.0011 and 0″.0049 ± 0.0008 have been calculated for the red giants 46 Leo and φ Aqr respectively from occultation observations. The occultation curves of α Lib and ε Cap show that they are binary systems. The separation of the components of the visual binary ε Ari, as calculated from its occultation curve, is 1.3 times its reported value. The occultation curve of α Leo shows distortion effects which are attributed to irregularities in the lunar limb.

scholarly journals Condensation of SiC in Circumstellar Dust Shells of C-Rich Red Giants

2000 ◽  
Vol 177 ◽  
pp. 532-532
Author(s):  
Andreas Gauger ◽  
John J. Ready ◽  
Erwin Sedlmayr
Keyword(s):  
Circumstellar Dust ◽  
Red Giants ◽  
Dust Shells

scholarly journals Calibrating the surface brightness – color relation for late-type red giants stars in the visible domain using VEGA/CHARA interferometric observations

2020 ◽  
Vol 639 ◽  
pp. A67 ◽  
Author(s):  
N. Nardetto ◽  
A. Salsi ◽  
D. Mourard ◽  
V. Hocdé ◽  
K. Perraut ◽  
...  
Keyword(s):  
Surface Brightness ◽  
Large Magellanic Cloud ◽  
Eclipsing Binaries ◽  
Red Giants ◽  
Average Precision ◽  
Giant Stars ◽  
Homogeneous Set ◽  
Red Giant ◽  
The One ◽  
Angular Diameters

Context. The surface brightness – color relationship (SBCR) is a poweful tool for determining the angular diameter of stars from photometry. It was for instance used to derive the distance of eclipsing binaries in the Large Magellanic Cloud (LMC), which led to its distance determination with an accuracy of 1%. Aims. We calibrate the SBCR for red giant stars in the 2.1 ≤ V − K ≤ 2.5 color range using homogeneous VEGA/CHARA interferometric data secured in the visible domain, and compare it to the relation based on infrared interferometric observations, which were used to derive the distance to the LMC. Methods. Observations of eight G–K giants were obtained with the VEGA/CHARA instrument. The derived limb-darkened angular diameters were combined with a homogeneous set of infrared magnitudes in order to constrain the SBCR. Results. The average precision we obtain on the limb-darkened angular diameters of the eight stars in our sample is 2.4%. For the four stars in common observed by both VEGA/CHARA and PIONIER/VLTI, we find a 1σ agreement for the angular diameters. The SBCR we obtain in the visible has a dispersion of 0.04 magnitude and is consistent with the one derived in the infrared (0.018 magnitude). Conclusions. The consistency of the infrared and visible angular diameters and SBCR reinforces the result of 1% precision and accuracy recently achieved on the distance of the LMC using the eclipsing-binary technique. It also indicates that it is possible to combine interferometric observations at different wavelengths when the SBCR is calibrated.

The Cosmic Mystery Tour

2019 ◽  
Author(s):  
Nicholas Mee
Keyword(s):  
Science Fiction ◽  
Particle Physics ◽  
Cultural Context ◽  
Big Bang ◽  
Galactic Centre ◽  
Red Giants ◽  
Extraterrestrial Life ◽  
Modern Physics ◽  
Recent Developments ◽  
The Universe

The Cosmic Mystery Tour is a brief account of modern physics and astronomy presented in a broad historical and cultural context. The book is attractively illustrated and aimed at the general reader. Part I explores the laws of physics including general relativity, the structure of matter, quantum mechanics and the Standard Model of particle physics. It discusses recent discoveries such as gravitational waves and the project to construct LISA, a space-based gravitational wave detector, as well as unresolved issues such as the nature of dark matter. Part II begins by considering cosmology, the study of the universe as a whole and how we arrived at the theory of the Big Bang and the expanding universe. It looks at the remarkable objects within the universe such as red giants, white dwarfs, neutron stars and black holes, and considers the expected discoveries from new telescopes such as the Extremely Large Telescope in Chile, and the Event Horizon Telescope, currently aiming to image the supermassive black hole at the galactic centre. Part III considers the possibility of finding extraterrestrial life, from the speculations of science fiction authors to the ongoing search for alien civilizations known as SETI. Recent developments are discussed: space probes to the satellites of Jupiter and Saturn; the discovery of planets in other star systems; the citizen science project SETI@Home; Breakthrough Starshot, the project to develop technologies to send spacecraft to the stars. It also discusses the Fermi paradox which argues that we might actually be alone in the cosmos

Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy

2000 ◽  
Vol 120 (2) ◽  
pp. 833-844 ◽  
Author(s):  
Solange V. Ramírez ◽  
Andrew W. Stephens ◽  
Jay A. Frogel ◽  
D. L. DePoy
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Red Giants ◽  
Galactic Bulge

scholarly journals Gaia DR2 data and the evolutionary status of eight high-velocity hot post-AGB candidates

2020 ◽  
Vol 72 (6) ◽  
Author(s):  
Mudumba Parthasarathy ◽  
Tadafumi Matsuno ◽  
Wako Aoki
Keyword(s):  
Effective Temperature ◽  
High Velocity ◽  
Circumstellar Dust ◽  
Evolutionary Status ◽  
Agb Stars ◽  
Horizontal Branch ◽  
Dust Shells ◽  
The Past ◽  
Gaia Dr2 ◽  
Branch Star

Abstract From Gaia DR2 data of eight high-velocity hot post-AGB candidates, LS 3593, LSE 148, LS 5107, HD 172324, HD 214539, LS IV −12 111, LS III +52 24, and LS 3099, we found that six of them have accurate parallaxes which made it possible to derive their distances, absolute visual magnitudes (MV) and luminosity (log L/L⊙). All the stars except LS 5107 have an accurate effective temperature (Teff) in the literature. Some of these stars are metal poor, and some of them do not have circumstellar dust shells. In the past, the distances of some stars were estimated to be 6 kpc, which we find to be incorrect. The accurate Gaia DR2 parallaxes show that they are relatively nearby, post-AGB stars. When compared with post-AGB evolutionary tracks we find their initial masses to be in the range 1 M⊙ to 2 M⊙. We find the luminosity of LSE 148 to be significantly lower than that of post-AGB stars, suggesting that this is a post-horizontal-branch star or post-early-AGB star. LS 3593 and LS 5107 are new high-velocity hot post-AGB stars from Gaia DR2.

scholarly journals Discovery of Infrared Stars in Globular Clusters in the Magellanic Clouds and Their Light Variations

1998 ◽  
Vol 11 (1) ◽  
pp. 395-395
Author(s):  
S. Nishida ◽  
T. Tanabé ◽  
S. Matsumoto ◽  
T. Onaka ◽  
Y. Nakada ◽  
...  
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Main Sequence ◽  
Near Infrared ◽  
Magellanic Clouds ◽  
Infrared Light ◽  
Agb Stars ◽  
Dust Shells ◽  
Infrared Stars ◽  
Infrared Survey

A systematic near-infrared survey was made for globular clusters in the Magellanic Clouds. Two infrared stars were discovered in NGC419 (SMC) and NGC1783 (LMC). NGC419 and NGC1783 are well-studied rich globular clusters whose turn-off masses and ages are estimated MTO ~ 2.0 Mʘ and т ~1.2 Gyr for NGC419, and MT0 ~ 2.0 Mʘ and т ʘ 0.9 Gyr for NGC1783, respectively. The periods of the infrared light variations were determined to be 540 dfor NGC419IR1 and to be 480 d for NGC1783IR1, respectively. Comparison of the measurements with the period—if magnitude relation for carbon Miras in the LMC by Groenewegen and Whitelock(1996) revealed that the Kmagnitudes of the infrared stars were fainter by about 0.3 — 0.8 magnitude than those predicted by the P — K relation. This deviation can be explained if the infrared stars are surrounded by thick dust shells and are obscured even in the K band. The positions of NGC419IR1and NGC1783IR1 on the P — K diagram suggest that AGB stars with the main sequence masses of about 2 Mʘ start their heavy mass-loss when P ʘ 500 d.

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