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Thursday, July 23, 2020 | History

3 edition of Carbon stars with oxygen-rich circumstellar material found in the catalog.

Carbon stars with oxygen-rich circumstellar material

Carbon stars with oxygen-rich circumstellar material

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Published by University of California, Los Angeles, Dept. of Astronomy, National Aeronautics and Space Administration in Los Angeles, Calif, [Washington, D.C .
Written in English

    Subjects:
  • Carbon stars.,
  • Cosmic dust.,
  • Interstellar extinction.,
  • Main sequence stars.,
  • Stellar envelopes.,
  • Stellar mass.,
  • Ultraviolet spectra.

  • Edition Notes

    Other titlesCarbon stars with oxygen rich circumstellar material.
    StatementM. Jura and I. Hawkins.
    SeriesNASA contractor report -- NASA/CR-190161.
    ContributionsHawkins, Isabel, 1958-, United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL18227658M

    The carbon star has a profile intermediate in width between the M giant and supergiant (indicating an intermediate luminosity), although the superposed circumstellar absorptions resemble more closely those in the supergiant. The h-line in the carbon star is even more mutilated by overlying circumstellar absorptions than the k-line and by. A carbon star is typically an asymptotic giant branch star, a luminous red giant, whose atmosphere contains more carbon than oxygen. The two elements combine in the upper layers of the star, forming carbon monoxide, which consumes all the oxygen in the atmosphere, leaving carbon atoms free to form other carbon compounds.

    Glassgold & Huggins (). We model the carbon-rich chemistry in the circumstellar region between ∼ and R (– 3 × cm). In the subsequent sections, we consider the chemical and further physical ingredients of our model. Observationally, very little is known about the chemistry of extragalactic carbon stars, and so. We report the detection of both (J = ) and (J = ) CO emission from the oxygen-rich circumstellar envelope around a carbon star with an oxygen-rich circumstellar envelope, BM Gem. The line has two distinct components.

    A circumstellar envelope is a part of a star that has a roughly spherical shape and is not gravitationally bound to the star core. Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before the formation of the star. Circumstellar envelopes of old stars eventually evolve into protoplanetary nebulae, and circumstellar envelopes of young stellar objects evolve into circumstellar . Crossed molecular beams experiments on dicarbon molecules, C 2 (X 1 Σ + g /a 3 Π u), with unsaturated hydrocarbons acetylene (C 2 H 2 (X 1 Σ + g)), ethylene (C 2 H 4 (X 1 A g)), methylacetylene (CH 3 CCH(X 1 A 1)), and allene (H 2 CCCH 2 (X 1 A 1)) were carried out at 18 collision energies between and kJ mol −1 utilizing a universal crossed beams machine to untangle the reaction Cited by:


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Carbon stars with oxygen-rich circumstellar material Download PDF EPUB FB2

The IUE satellite was used to search for companions to two carbon-rich stars with oxygen-rich circumstellar envelopes, EU And and V Cyg. Depending upon the amount of interstellar extinction and distances (probably between 1 and 2 kpc from the Sun) to these two stars, upper limits were placed between approx.

and 6 solar mass to the mass of any main sequence : Michael Jura, I. Hawkins. Carbon Star Spectral Synthesis Star Progenitor Circumstellar Shell Silicate Dust These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm : Silvia Lorenz Martins, Sayd José Codina Landaberry.

Get this from a library. Carbon stars with oxygen-rich circumstellar material. [Michael Jura; Isabel Hawkins; United States. National Aeronautics and Space Administration.]. Abstract. LTE calculations of the chemistry of circumstellar envelopes CSEs surrounding oxygen-rich late type stars show the carbon to be tied up in CO with the excess oxygen forming other molecules such as H 2 O (Tsuji ).

So the first observations of carbon-bearing molecules in such sources were somewhat : Karen Willacy, T. Millar. Carbon stars with oxygen-rich circumstellar material. By Michael Jura and I. Hawkins. Abstract. The IUE satellite was used to search for companions to two carbon-rich stars with oxygen-rich circumstellar envelopes, EU And and V Cyg.

Depending upon the amount of interstellar extinction and distances (probably between 1 and 2 kpc from the Sun Author: Michael Jura and I. Hawkins. The circumstellar environment of evolved stars is generally rich in molecular gas and dust.

Typically, the entire environment is either oxygen-rich or carbon-rich, depending on the evolution of the central star. Aims. In this paper we discuss three evolved disc sources with evidence of atypical emission lines in their infrared by: In the new version of the catalogue of carbon stars, IRAS + is listed as a carbon-rich sta.

However, in the IRAS infrared two-color diagram, it is located in the typical region of stars with rather thick oxygen-rich circumstellar envelopes, and not in the region commonly occupied by silicate carbon by: 1.

Mass loss from evolved stars results in the formation of unusual chemical laboratories: circumstellar envelopes.

Such envelopes are found around carbon- and oxygen-rich asymptotic giant branch stars and red by: The carbon stars are of tw o types, the red N stars of the extended giant branch, formed by the third dredge-up process, and fainter, bluer stars such as those in the Draco dSph galaxy (Aaronson.

Context. Despite their carbon-rich photospheres, silicate carbon stars show evidence of oxygen-rich circumstellar material, which is thought to exist in disks. Silicate carbon stars represent interesting cases that allow us to study the possible effects of binarity on stellar evolution and mass loss accompanied by the formation of disks.

/> Aims: We present a small survey of 22 GHz H2 Cited by: 1. We report observations of oxygen-rich (O-rich) radio molecular line tracers, including H 2CO, H 2O, and HCO + toward 28 silicate carbon stars (SCSs). SCSs are special evolved star systems that consist of a carbon star associated with peculiar O-rich circumstellar material.

Absorption in the 6cm H 2CO transition was detected fromAuthor: Zhang Zhao, Xi Chen, Xi Chen, Simon P.

Ellingsen, Andrej M. Sobolev, Xujia Ouyang. Observations of the red supergiant star VY Canis Majoris show that in the limited environment of the outflow from an oxygen-rich star, only half the carbon is contained in by: The outflow of material creates a circumstellar envelope (CSE), which is characterised by a rich chemistry.

The type of chemistry is characterised by the elemental carbon-to-oxygen abundance ratio: oxygen-rich M-type stars have C/O carbon-rich stars have C/O > 1, and S-type stars have C/O ˇ1.

The driving mechanism of the AGB outflow is Cited by:   Page 1 of 2 - Carbon Star list by season - posted in General Observing and Astronomy: I am afraid my Google Fu failed me. I looked high and low for a list of Carbon Stars by month/season and came up with a few outdated links with file formats that do not work anymore (olf format).

So if anyone has a list or a link to a list that would be great. Written by selected astronomers at the forefront of their fields, this timely and novel book compiles the latest results from research on white dwarf stars, complementing existing literature by focusing on fascinating new developments in our understanding of the atmospheric and circumstellar environments of these stellar remnants.5/5(1).

a water maser associated with eu andromedae: a carbon star near an oxygen-rich circumstellar shell Users without a subscription are not able to see the full content.

Please, subscribe or login to. Carbon stars are typically evolved cool giants with some circumstellar material in the form of shells, soot, disks, or clouds. Carbon compounds are present in the photosphere after a star enters the red-giant evolutionary phase, when heavy elements (such as carbon) are dredged up from the stellar interior.

One of the few carbon-rich environments found in interstellar space is the ejecta of asymptotic giant branch (AGB) stars. Such material, which forms a circumstellar envelope, becomes enriched in carbon due to dredge-up phenomena associated with by: 2.

INTRODUCTION The discovery of emission features at 10 /Lm and 18 ym in the circumstellar envelopes of visual carbon stars was one of the unexpected and important results from the IRAS Low-Resolution Spectra (LRS).

Emissions at 10 tim and 18 jam produced from silicate dust generally exist in oxygen-rich circumstellar by: 4. 86 works Search for books with subject Ultraviolet spectra. Search. Borrow. Ultra-violet and visible spectroscopy C. Rao Carbon stars with oxygen-rich circumstellar material Michael JuraReflection (Optics), Solar radiation, Binary stars, Carbon disulphide, Charts, diagrams, Circumstellar matter, Electric furnaces.

Welcome to the Astronomical League’s Carbon Star Observing Program! Carbon stars are a unique and interesting type of variable star that exhibits peculiar characteristics and spectra.

Most are red giant stars, and their distinguishing feature (and namesake) is the unusually high level of carbon molecules contained in their atmospheres.The chemistry will be dominated by the remaining oxygen, leading to the formation of oxygen-rich molecules and particles, e.g.

silicates and oxides. This is the case for M-type AGB stars. In this chapter, the µm spectra of M-type AGB stars will be studied with a view to identifying the oxygen-rich dust species forming around such stars.like to be able to separate the carbon-rich from the oxygen-rich CSEs based purely on MSXcolors.

But before investigating such a separation in Section 3, we compare the “evolutionary curve” of oxygen-rich stars with circumstellar material in the IRAS 2CD as described by van der Veen & Habing () with MSX colors.

Note that this.