Results 51 to 60 of about 58,021 (177)

Characterizing the dynamical magnetosphere of the extremely slowly rotating magnetic O9.7 V star HD 54879 using rotational modulation of the Hα profile

Astronomische Nachrichten, Volume 345, Issue 4, May 2024.
Abstract The magnetic field in the O9.7 V star HD 54879 has been monitored for almost a decade. Spectropolarimetric observations reveal a rather strong mean longitudinal magnetic field that varies with a period of about 7.41 years. Observations in the Hα$$ \alpha $$ line show a variation with the same period, while the Hβ$$ \beta $$ line shows only ...
Manfred Küker, S. P. Järvinen, S. Hubrig, Ilya Ilyin, M. Schöller   +4 more
wiley   +1 more source

Effects of Metallicity on Graphite, TiC, and SiC Condensation in Carbon Stars

The Astrophysical Journal
From transmission electron microscopy and other laboratory studies of presolar grains, the implicit condensation sequence of carbon-bearing condensates in circumstellar envelopes of carbon stars is (from first to last) TiC-graphite-SiC.
Gabrielle M. Adams, Katharina Lodders
doaj   +1 more source

Early Planet Formation in Embedded Disks (eDisk). XIII. Aligned Disks with Nonsettled Dust around the Newly Resolved Class 0 Protobinary R CrA IRAS 32

The Astrophysical Journal
Young protostellar binary systems, with expected ages less than ∼10 ^5 yr, are little modified since birth, providing key clues to binary formation and evolution. We present a first look at the young, Class 0 binary protostellar system R CrA IRAS 32 from
Frankie J. Encalada, Leslie W. Looney, Shigehisa Takakuwa, John J. Tobin, Nagayoshi Ohashi, Jes K. Jørgensen, Zhi-Yun Li, Yuri Aikawa, Yusuke Aso, Patrick M. Koch, Woojin Kwon, Shih-Ping Lai, Chang Won Lee, Zhe-Yu Daniel Lin, Alejandro Santamaría-Miranda, Itziar de Gregorio-Monsalvo, Nguyen Thi Phuong, Adele Plunkett, Jinshi Sai (Insa Choi), Rajeeb Sharma, Hsi-Wei Yen, Ilseung Han   +21 more
doaj   +1 more source

PAH formation in carbon-rich circumstellar envelopes [PDF]

, 1989
While there is growing observational evidence that some fraction of interstellar carbon is in polycyclic aromatic hydrocarbons (PAH's), the mechanisms by which these molecules might be formed have not been extensively studied. A detailed investigation of
Feigelson, Eric D., Frenklach, Michael
core  

Reflections on the photodissociation of CO in circumstellar envelopes

, 2021
Carbon monoxide (CO) is the most abundant molecule after molecular hydrogen and is important for the chemistry in circumstellar envelopes around evolved stars.
M. A. T. Groenewegen, M. Saberi, Groenewegen, Martin, Saberi, Maryam   +3 more
core   +1 more source

IR emission from circumstellar envelopes of C-rich stars [PDF]

, 1989
The reliability of a theoretical model that solves the radiative transfer equation in dust clouds surrounding a central star is checked. In particular, it is found that both classical scattering by dust and the back-heating effects are negligible in the ...
Colangeli, Luigi, Fonti, Sergio, Orofino, Vincenso, Bussoletti, E., Blanco, A., Borghesi, A.   +5 more
core  

Small scale structure in circumstellar envelopes and the origin of globules in planetary nebulae

, 2002
We analyze the small scale structure in the circumstellar envelopes of NGC 7027 and IRC+10216, using high resolution optical images in dust scattered light.
P. J. Huggins, N. Mauron
core   +1 more source

Observations of Molecular CN toward S-type Asymptotic Giant Branch Stars

The Astronomical Journal
S-type asymptotic giant branch (AGB) stars are defined by their carbon-to-oxygen (C/O) ratio approaching unity. However, observations of circumstellar molecules in these stars are limited and challenging.
Yanan Feng, Xiaohu Li, Xiaofeng Yang, Tom J. Millar, Ryszard Szczerba, Sheng-Li Qin, Xuejian Jiang, Donghui Quan, Juan Tuo, Zhenzhen Miao, Sheng-Yuan Liu, Xiang Liu   +11 more
doaj   +1 more source

The ultraviolet extinction in M-supergiant circumstellar envelopes [PDF]

, 1986
Using International Ultraviolet (IUS) archival low-dispersion spectra, ultraviolet spectral extinctions were derived for the circumstellar envelopes of two M supergiants: HD 60414 and HD 213310.
Buss, R. H., Jr., Snow, T. P., Jr.
core  

A circumstellar journey-physics and chemistry of AGB stellar winds

, 2008
The physics and chemistry of the envelopes of gas and dust that surround stars on the asymptotic giant branch are the subjects of this review. Estimates of stellar mass-loss rates in this phase, as determined through observations and modelling of ...
Olofsson, Hans,, Olofsson, Hans
core   +1 more source