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The heavy mass loss observed in evolved asymptotic giant branch (AGB) stars is usually attributed to a two-stage process: atmospheric levitation by pulsation-induced shock waves, followed by radiative acceleration of newly formed dust…

Solar and Stellar Astrophysics · Physics 2015-06-15 Sara Bladh , Susanne Höfner , Walter Nowotny , Bernhard Aringer

We explored an efficient method to identify evolved stars with oxygen-rich envelopes in the late AGB or post-AGB phase of stellar evolution, which include a rare class of objects - the "water fountains". Our method considers the OH and H2O…

Solar and Stellar Astrophysics · Physics 2015-06-22 Bosco Yung , Jun-ichi Nakashima , Christian Henkel

Asymptotic giant branch (AGB) stars are significant contributors to the chemical enrichment of the interstellar medium (ISM) of galaxies. It is therefore essential to constrain the AGB contribution to the dust budget in galaxies. Recent…

Solar and Stellar Astrophysics · Physics 2016-08-02 Sundar Srinivasan , Franciska Kemper , Ronny Zhao-Geisler

Aims. This study focuses on very luminous Mbol<-6.0 mag AGB stars with J-Ks>1.5 mag and H-Ks>0.4 mag in the LMC, SMC, M31, and M33 from 2MASS data. Methods.The data were taken from the 2MASS All-Sky Point Source catalogue archive. We used…

Astrophysics · Physics 2016-08-30 P. Tsalmantza , E. Kontizas , L. Cambresy , F. Genova , A. Dapergolas , M. Kontizas

We conducted radio observations searching for OH 18-cm maser emission from a sample of 169 unclassified MIPSGAL compact Galactic bubbles. These sources are thought to be the circumstellar envelopes of different kinds of evolved stars. Our…

Solar and Stellar Astrophysics · Physics 2015-10-02 A. Ingallinera , C. Trigilio , P. Leto , G. Umana , C. Buemi , L. Cerrigone , C. Agliozzo

We have searched for near-infrared stellar counterparts of IRAS point sources in the Large Magellanic Cloud (LMC), in J and K-bands. This resulted in the detection of 21 counterparts, of which 19 are new discoveries. Using colour-magnitude…

Studying stars that are located off the Galactic plane is important for understanding the formation history of the Milky Way. We searched for SiO masers toward off-plane O-rich asymptotic giant branch (AGB) stars from the catalog presented…

Astrophysics of Galaxies · Physics 2023-10-23 Wenjin Yang , Yuanwei Wu , Yan Gong , Nicolas Mauron , Bo Zhang , Karl M. Menten , Xiaofeng Mai , Dejian Liu , Juan Li , Jingjing Li

We have identified a new vibrational HCN maser at 89.087 GHz in the asymptotic giant branch (AGB) star IRAS 15082-4808, a maser which is thought to trace the innermost region of an AGB envelope. The observations of this maser at three…

Solar and Stellar Astrophysics · Physics 2015-06-18 C. L. Smith , A. A. Zijlstra , G. A. Fuller

To ascertain the nature of the brightest compact mid-infrared sources in the Large Magellanic Cloud (LMC), we have applied an updated version of the Buchanan et al. (2006) 2MASS-MSX color classification system, which is based on the results…

We aim to detect the magnetic field and infer its properties around four AGB stars using H$_2$O maser observations. The sample we observed consists of the following sources: the semi-regular variable RT Vir and the Mira variables AP Lyn, IK…

Solar and Stellar Astrophysics · Physics 2015-06-15 M. L. Leal-Ferreira , W. H. T. Vlemmings , A. Kemball , N. Amiri

Very Large Array observations of the Galactic Center at 7 mm have produced an image of the 30 arcseconds surrounding Sgr A* with a resolution of 82x42 milliarcseconds (mas). A comparison with IR images taken simultaneously with the Very…

Astrophysics of Galaxies · Physics 2015-06-22 F. Yusef-Zadeh , D. A. Roberts , H. Bushouse , M. Wardle , W. Cotton , M. Royster , G. van Moorsel

High spatial resolution techniques have given valuable insights into the mass loss mechanism of AGB stars, which presumably involves a combination of atmospheric levitation by pulsation-induced shock waves and radiation pressure on dust.…

Solar and Stellar Astrophysics · Physics 2016-10-19 Susanne Höfner , Sara Bladh , Bernhard Aringer , Rajeev Ahuja

We probe the radial clumping stratification of OB stars in the intermediate and outer wind regions (r>~2 R*) to derive upper limits for mass-loss rates, and compare to current mass-loss implementation. Together with archival…

Solar and Stellar Astrophysics · Physics 2022-02-02 M. M. Rubio-Díez , J. O. Sundqvist , F. Najarro , A. Traficante , J. Puls , L. Calzoletti , D. Figer

Mapping and monitoring observations of SiO maser sources near the Galactic center were made with the Nobeyama 45-m telescope at 43 GHz. Rectangular mapping an area of approximately 200'' x 100''$ in a 30'' grid, and triangular mapping in a…

Astrophysics · Physics 2015-06-24 Shuji Deguchi , Takahiro Fujii , Makoto Miyoshi , Jun-ichi Nakashima

We report the first study of OH(1720 MHz) masers in the LMC in order to probe regions where supernova remnants interact with adjacent molecular clouds. Using the ATCA, we observed four sources in the LMC and detected a single OH(1720 MHz)…

Astrophysics · Physics 2007-05-23 D. A. Roberts , F. Yusef-Zadeh

The mass-loss rates and dust-to-gas ratios of obscured Asymptotic Giant Branch (AGB) stars are investigated for samples with different initial metallicities: in the Small and Large Magellanic Clouds (SMC & LMC) and in the Milky Way. The…

Astrophysics · Physics 2007-05-23 Jacco Th. van Loon

The mechanism of mass loss in late evolutionary stages of low- and intermediate-mass stars is not yet well understood. Therefore, it is crucial to study the dynamics of the region within a few stellar radii, where the wind acceleration is…

Solar and Stellar Astrophysics · Physics 2019-10-02 Keiichi Ohnaka , Gerd Weigelt , Karl-Heinz Hofmann

A sample of OB stars (eleven Of, one O and one B supergiant) has been surveyed with the Australia Telescope Compact Array at 4.8 and 8.64 GHz with a resolution of 2'' -- 4''. Five stars were detected; three of them have negative spectral…

Astrophysics · Physics 2009-11-06 P. Benaglia , C. E. Cappa , B. S. Koribalski

Stellar winds observed in asymptotic giant branch (AGB) stars are usually attributed to a combination of stellar pulsations and radiation pressure on dust. Shock waves triggered by pulsations propagate through the atmosphere, compressing…

Solar and Stellar Astrophysics · Physics 2015-06-23 S. Bladh , S. Höfner , B. Aringer , K. Eriksson

We detect high-velocity absorbing gas using Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer medium resolution spectroscopy along two high-latitude AGN sight lines (Mrk 1383 and PKS 2005-489) above and below the Galactic…