dc.creator |
Men'shchikov, A. B. |
|
dc.creator |
Balega, Y. Y. |
|
dc.creator |
Berger, M. |
|
dc.creator |
Driebe, T. |
|
dc.creator |
Hofmann, K.-H. |
|
dc.creator |
Maximov, A. F. |
|
dc.creator |
Schertl, D. |
|
dc.creator |
Shenavrin, V. I. |
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dc.creator |
Weigelt, G. |
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dc.date.accessioned |
2015-04-16T15:45:00Z |
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dc.date.available |
2015-04-16T15:45:00Z |
|
dc.date.issued |
2006-03 |
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dc.identifier.issn |
0004-6361 |
|
dc.identifier.uri |
http://library2.smu.ca/xmlui/handle/01/26051 |
|
dc.description |
Publisher's version/PDF |
en_CA |
dc.description.abstract |
We present the near-infrared speckle interferometry for LP And in the H and K’ bands with diffraction-limited resolutions of 56 and 72 mas, new JHKLM photometry, and the results of our radiative transfer modelling of this carbon star. The reconstructed visibility reveals a spherically symmetric envelope surrounding the central star. To determine the physical parameters of the latter and the properties of its dusty envelope, we performed extensive radiative transfer calculations. The well-defined spectral energy distribution of LP And in the entire range from the near-IR to millimeter wavelengths (including the absorption feature visible in the stellar continuum at 3 [micrometres] and the shapes of the dust emission bands at 11 and 27 [micrometres]), together with our H-band visibility can be reproduced by a spherical dust envelope with parameters that are very similar to those of CW Leo (IRC+10216), the best studied carbon star. For the newly estimated pulsation period P = 617 [plus or minus] 6 days and distance D = 740 [plus or minus] 100 pc, our model of LP And changes its luminosity L[subscript *] between 16 200 and 2900 L[subscript circled dot], its effective temperature T[subscript *] between 3550 and 2100 K, and its radius R[subscript *] between 340 and 410 R[subscript circled dot]. The model estimates the star’s mass-loss rate [dot above M] [approximately equal to] 1.9 × 10[superscript −5] M[subscript circled dot] yr[superscript −1], assuming a constant outflow velocity v = 14 km s[superscript −1]. If the latter also applied to the innermost parts of the dusty envelope, then presently the star would be losing mass at a rate [dot above M] [approximately equal to] 6.0 × 10[superscript −5] M[subscript circled dot] yr[superscript −1]. However, we believe that the inner wind velocity must actually be closer to v [approximately equal to] 4 km s[superscript −1] instead, as wind acceleration is expected in the dust-formation zone. The dusty envelope of LP And extends from R[subscript 1] [approximately equal to] 2 R[subscript *] to distances of R[subscript 2] [approximately equal to] 3 pc from the star. The total mass of the envelope lost by the central star is M = 3.2 M[subscript circled dot] assuming a dust-to-gas mass ratio of [rho][subscript d]/[rho] = 0.0039. The circumstellar optical depth towards the star is [tau][subscript V] = 25 in the visual. The dust model contains small silicon carbide grains, inhomogeneous grains made of a mixture of SiC and incompletely amorphous carbon, and thin mantles made of iron-magnesium sulfides. This dust mixture perfectly fits the infrared continuum and both the 11.3 [micrometres] and 27 [micrometres] emission bands. We find that our K’-band visibility could not be fitted by our spherical model, so we discuss possible reasons for this interesting result. More observations are required in order to determine what causes this effect. If slight deviations from spherical geometry in its envelope are the reason, then the object’s evolutionary stage would be even more similar to that of CW Leo. It appears that LP And is a highly-evolved intermediate-mass star (initial mass M[superscript 0][subscript *] [approximately equal to] 4 M[subscript circled dot]) at the end of its AGB phase. |
en_CA |
dc.description.provenance |
Submitted by Janine Mills (janine.mills@smu.ca) on 2015-04-16T15:45:00Z
No. of bitstreams: 1
Menshchikov_AB_article_2006.pdf: 739377 bytes, checksum: 3765b09b478182d2bf12187c3320d442 (MD5) |
en |
dc.description.provenance |
Made available in DSpace on 2015-04-16T15:45:00Z (GMT). No. of bitstreams: 1
Menshchikov_AB_article_2006.pdf: 739377 bytes, checksum: 3765b09b478182d2bf12187c3320d442 (MD5)
Previous issue date: 2006 |
en |
dc.language.iso |
en |
en_CA |
dc.publisher |
European Southern Observatory |
en_CA |
dc.publisher |
EDP Sciences |
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dc.relation.uri |
http://dx.doi.org/10.1051/0004-6361:20052976 |
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dc.rights |
Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user. |
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dc.subject.lcsh |
Radiative transfer |
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dc.subject.lcsh |
Circumstellar matter |
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dc.subject.lcsh |
Asymptotic giant branch stars |
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dc.subject.lcsh |
Mass loss (Astrophysics) |
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dc.subject.lcsh |
Space interferometry |
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dc.title |
Near-infrared speckle interferometry and radiative transfer modelling of the carbon star LP Andromedae |
en_CA |
dc.type |
Text |
en_CA |
dcterms.bibliographicCitation |
Astronomy & Astrophysics 448(1), 271-281. (2006) |
en_CA |
Copyright statement:
Article is made available in accordance with the publisher’s policy and is subject to copyright law. Please refer to the publisher’s site. Any re-use of this article is to be in accordance with the publisher’s copyright policy. This posting is in no way granting any permission for re-use to the reader/user.