scholarly journals Carbon star CGCS 673 identified as a semi-regular variable star

2020 ◽  
Vol 20 (11) ◽  
pp. 177
Author(s):  
Stephen M. Brincat ◽  
Charles Galdies ◽  
Kevin Hills
Keyword(s):  
Variable Star ◽  
Carbon Star ◽  
Regular Variable

scholarly journals Annual parallax measurements of a semi-regular variable star, RW Leporis

2014 ◽  
Vol 66 (6) ◽  
pp. 107 ◽  
Author(s):  
Tatsuya Kamezaki ◽  
Tomoharu Kurayama ◽  
Akiharu Nakagawa ◽  
Toshihiro Handa ◽  
Toshihiro Omodaka ◽  
...  
Keyword(s):  
Variable Star ◽  
Regular Variable

scholarly journals VLBI astrometry of the semi-regular variable star RX Bootis

2012 ◽  
Vol 8 (S289) ◽  
pp. 91-94
Author(s):  
Tatsuya Kamezaki ◽  
Akiharu Nakagawa ◽  
Toshihiro Omodaka ◽  
Toshihiro Handa ◽  
Hiroshi Imai ◽  
...  
Keyword(s):  
Variable Star ◽  
Absolute Magnitude ◽  
Distance Measurement ◽  
Reference Source ◽  
Maser Spot ◽  
Regular Variable ◽  
The Absolute ◽  
Stellar Properties ◽  
Water Maser ◽  
The Continuum

AbstractWe present a distance measurement to the semi-regular variable star RX Bootis (RX Boo). Using the VLBI Exploration of Radio Astrometry (VERA) telescope, we conducted astrometric observations of a water maser spot associated with RX Boo, as well as of the continuum reference source J1419+2706. Based on monitoring observations covering a full year, the annual parallax of RX Boo was measured at 7.31 ± 0.50 mas, corresponding to a distance of 136+10−9 pc. This distance uncertainty is smaller by a factor of two than those previously published, allowing us to determine the object's stellar properties more accurately. Using our distance, we can determine the absolute magnitude and discuss more precisely the locus of RX Boo on the period–luminosity (PL) relation. RX Boo exhibits two simultaneous pulsation periods and is located on the fundamental and first overtone Mira sequences of the PL relation. In addition, we calculated the radius and mass of the star.

scholarly journals Overall variation of the H2O masers around W Hydrae in 28 years

2019 ◽  
Author(s):  
Hiroshi Imai ◽  
Akiharu Nakagawa ◽  
Hiroshi Takaba
Keyword(s):  
Variable Star ◽  
Spherical Geometry ◽  
Spot Size ◽  
Radio Link ◽  
Very Large Array ◽  
Maser Spot ◽  
Spatially Resolved ◽  
Stellar Pulsation ◽  
Regular Variable ◽  
Physical Boundary

Abstract In this paper, we present the distribution of H$_2$O masers associated with the semi-regular variable star W Hydrae (W Hya). We have collected the radio interferometric data of the maser distribution taken with the Very Large Array (VLA), the Kashima–Nobeyama InterFErometer (KNIFE), the Multi-Element Radio Link Network (MERLIN), the VLBI Exploration of Radio Astrometry (VERA), and the combined array of the Korean VLBI Network (KVN) and VERA (KaVA) in order to trace the maser distribution variation in two decades. Even though differences in the sensitivities and angular resolutions of the interferometric observations should be taken into account, we attempt to find possible correlation of the maser distribution with the stellar light curve. Our failure in the measurement of the annual parallax of the masers with VERA is likely caused by the properties of the maser features, which have been spatially resolved by the synthesized beam and survived for only half a year or less. No dependence of the maser spot flux density on its size is found in the KNIFE data, suggesting that maser spot size is determined by the physical boundary, as is expected for a clump affected by outward propagation of a stellar pulsation shock wave, rather than the (spherical) geometry of maser beaming in the maser gas clump.

scholarly journals VLBI studies of SiO masers around VX Sagittarii

2007 ◽  
Vol 3 (S242) ◽  
pp. 312-313
Author(s):  
X. Chen ◽  
Z.-Q. Shen ◽  
D.-R. Jiang
Keyword(s):  
Variable Star ◽  
Circumstellar Envelope ◽  
Preliminary Results ◽  
Regular Variable

AbstractObservations of 43 GHz 28SiO (v = 1, J = 1-0) masers in the circumstellar envelope of the M-type semi-regular variable star VX Sgr were performed using the VLBA at 3 epochs during 1999 April-May. By tracing 42 matched maser features appearing in all the three epochs, we determined the contraction of an SiO maser shell toward VX Sgr at a velocity of about 4 km s−1 at a distance of 1.7 kpc to VX Sgr. We also report on some preliminary results from our first epoch of simultaneous VLBA observations of three 7 mm SiO masers toward VX Sgr.

scholarly journals VLBI Monitoring Observations of Water Masers around the Semi-Regular Variable Star R Crateris

2001 ◽  
Vol 53 (6) ◽  
pp. 1231-1238 ◽  
Author(s):  
José K. Ishitsuka ◽  
Hiroshi Imai ◽  
Toshihiro Omodaka ◽  
Munetaka Ueno ◽  
Osamu Kameya ◽  
...  
Keyword(s):  
Variable Star ◽  
Regular Variable ◽  
Water Masers

scholarly journals Annual parallax measurements of a semi-regular variable star SV Pegasus with VERA

2018 ◽  
Vol 71 (1) ◽  
Author(s):  
Hiroshi Sudou ◽  
Toshihiro Omodaka ◽  
Kotone Murakami ◽  
Takahiro Nagayama ◽  
Akiharu Nakagawa ◽  
...  
Keyword(s):  
Variable Star ◽  
Regular Variable

On the Inhomogeneity of Chemical Composition over the Surface of 21 Per

1976 ◽  
Vol 32 ◽  
pp. 343-349
Author(s):  
Yu.V. Glagolevsky ◽  
K.I. Kozlova ◽  
V.S. Lebedev ◽  
N.S. Polosukhina
Keyword(s):  
Chemical Composition ◽  
Spectral Line ◽  
Variable Star ◽  
Radial Velocities ◽  
Crimean Astrophysical Observatory ◽  
Line Intensities ◽  
Magnetic Variable

SummaryThe magnetic variable star 21 Per has been studied from 4 and 8 Å/mm spectra obtained with the 2.6 - meter reflector of the Crimean Astrophysical Observatory. Spectral line intensities (Wλ) and radial velocities (Vr) have been measured.

Production of New and Revised A.A.V.S.O. Charts

1979 ◽  
Vol 46 ◽  
pp. 368
Author(s):  
Clinton B. Ford
Keyword(s):  
Variable Star ◽  
Standard Form ◽  
Original Data ◽  
University Of Pennsylvania ◽  
Standard Format ◽  
Additional Information ◽  
The Gift ◽  
The University

A “new charts program” for the Americal Association of Variable Star Observers was instigated in 1966 via the gift to the Association of the complete variable star observing records, charts, photographs, etc. of the late Prof. Charles P. Olivier of the University of Pennsylvania (USA). Adequate material covering about 60 variables, not previously charted by the AAVSO, was included in this original data, and was suitably charted in reproducible standard format.Since 1966, much additional information has been assembled from other sources, three Catalogs have been issued which list the new or revised charts produced, and which specify how copies of same may be obtained. The latest such Catalog is dated June 1978, and lists 670 different charts covering a total of 611 variables none of which was charted in reproducible standard form previous to 1966.

Polarimetric Observations of Red Variables: A Study of Gas and Particle Interactions

1979 ◽  
Vol 46 ◽  
pp. 386-408 ◽  
Author(s):  
G. V. Coyne ◽  
I. S. McLean
Keyword(s):  
Wavelength Dependence ◽  
Stellar Atmosphere ◽  
Molecular Absorption ◽  
Absorption Bands ◽  
Absorption And Emission ◽  
Mira Variables ◽  
Stellar Photosphere ◽  
Regular Variable ◽  
Red Supergiants ◽  
Balmer Lines

AbstractIn recent years the wavelength, dependence of the polarization in a number of Mira variables, semi-regular variables and red supergiants has been measured with resolutions between 0.3 and 300 A over the range 3300 to 11000 A. Variations are seen across molecular absorption bands, especially TiO bands, and across atomic absorption and emission lines, especially the Balmer lines. In most cases one can ignore or it is possible to eliminate the effects due to interstellar polarization, so that one can study the polarization mechanisms operating in the stellar atmosphere and environment. The stars Omicron Ceti. (Mira), V CVn (semi-regular variable) and Mu Cephei (M2 la), in addition to other stars similar to them, will be discussed in some detail.Models to explain the observed polarization consider that the continuum flux is polarized either by electron, molecular and/or grain scattering or by temperature variations and/or geometrical asymmetries over the stellar photosphere. This polarized radiation is affected by atomic and molecular absorption and emission processes at various geometric depths in the stellar atmosphere and envelope. High resolution spectropolarimetry promises, therefore, to be a power-rul tool for studying stratification effects in these stars.

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