Results 71 to 80 of about 55,649 (206)
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 +4 more
wiley +1 more source
Effects of Metallicity on Graphite, TiC, and SiC Condensation in Carbon Stars
The Astrophysical JournalFrom 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
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
The Astrophysical JournalYoung 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 +21 more
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Polarimetry as a Diagnostic of Circumstellar Envelopes [PDF]
International Astronomical Union Colloquium, 2000 AbstractPolarimetric observations of stars can provide useful diagnostics of the geometry and physical conditions of the circumstellar envelope. This paper reviews the application of polarimetric techniques to hot stars (with particular emphasis on Be stars) and the status of polarization observations, and discusses some recent developments that ...
openaire +1 more source
A deep search for C2H in the oxygen-rich post-AGB star OH 231.8+4.2
Frontiers in Astronomy and Space SciencesIn carbon-rich environment, C2H emission is seen to be associated with HC3N, but whether it can trace the HC3N molecule in oxygen-rich environment is unknown.
Jianchao Yang +5 more
doaj +1 more source
Observations of Molecular CN toward S-type Asymptotic Giant Branch Stars
The Astronomical JournalS-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 +11 more
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The unique chemistry in the envelopes of massive stars
Frontiers in Astronomy and Space SciencesThe envelopes of evolved massive stars (M ∼9–40 M⊙) on the Red Supergiant (RSG) Branch offer a unique situation to examine extreme circumstellar chemistry.
Lucy M. Ziurys
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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
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The Astronomical JournalThe carrier of the 21 μ m emission feature discovered in a handful of protoplanetary nebulae (PPNe) is one of the most intriguing enigmas in circumstellar chemistry.
Jian-Jie Qiu +9 more
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