NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS
Recently published Spitzer Space Telescope observations of the classical Cepheid archetype δ Cephei revealed an extended dusty nebula surrounding this star and its hot companion HD 213307. At far-infrared wavelengths, the emission resembles a bow shock aligned with the direction of space motion of t...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | en_US |
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IOP Publishing
2015
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| Online Access: | http://hdl.handle.net/1721.1/95470 |
| _version_ | 1826217377139785728 |
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| author | Marengo, Massimo Evans, N. R. Bono, G. Matthews, Lynn D. |
| author2 | Haystack Observatory |
| author_facet | Haystack Observatory Marengo, Massimo Evans, N. R. Bono, G. Matthews, Lynn D. |
| author_sort | Marengo, Massimo |
| collection | MIT |
| description | Recently published Spitzer Space Telescope observations of the classical Cepheid archetype δ Cephei revealed an extended dusty nebula surrounding this star and its hot companion HD 213307. At far-infrared wavelengths, the emission resembles a bow shock aligned with the direction of space motion of the star, indicating that δ Cephei is undergoing mass loss through a stellar wind. Here we report H I 21 cm line observations with the Very Large Array (VLA) to search for neutral atomic hydrogen associated with this wind. Our VLA data reveal a spatially extended H I nebula (~13' or 1 pc across) surrounding the position of δ Cephei. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the interstellar medium (ISM). We directly measure a mass of circumstellar atomic hydrogen M[subscript HI] ≈ 0.07 M [subscript ʘ], although the total H I mass may be larger, depending on the fraction of circumstellar material that is hidden by Galactic contamination within our band or that is present on angular scales too large to be detected by the VLA. It appears that the bulk of the circumstellar gas has originated directly from the star, although it may be augmented by material swept from the surrounding ISM. The H I data are consistent with a stellar wind with an outflow velocity V [subscript o] = 35.6 ± 1.2 km s[superscript –1] and a mass-loss rate of [dot over M] ≈ (1.0 ± 0.8) x 10[superscript -6] M [subscript ʘ] yr[superscript –1]. We have computed theoretical evolutionary tracks that include mass loss across the instability strip and show that a mass-loss rate of this magnitude, sustained over the preceding Cepheid lifetime of δ Cephei, could be sufficient to resolve a significant fraction of the discrepancy between the pulsation and evolutionary masses for this star. |
| first_indexed | 2024-09-23T17:02:42Z |
| format | Article |
| id | mit-1721.1/95470 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:02:42Z |
| publishDate | 2015 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/954702022-10-03T10:00:20Z NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS Marengo, Massimo Evans, N. R. Bono, G. Matthews, Lynn D. Haystack Observatory Matthews, Lynn D. Recently published Spitzer Space Telescope observations of the classical Cepheid archetype δ Cephei revealed an extended dusty nebula surrounding this star and its hot companion HD 213307. At far-infrared wavelengths, the emission resembles a bow shock aligned with the direction of space motion of the star, indicating that δ Cephei is undergoing mass loss through a stellar wind. Here we report H I 21 cm line observations with the Very Large Array (VLA) to search for neutral atomic hydrogen associated with this wind. Our VLA data reveal a spatially extended H I nebula (~13' or 1 pc across) surrounding the position of δ Cephei. The nebula has a head-tail morphology, consistent with circumstellar ejecta shaped by the interaction between a stellar wind and the interstellar medium (ISM). We directly measure a mass of circumstellar atomic hydrogen M[subscript HI] ≈ 0.07 M [subscript ʘ], although the total H I mass may be larger, depending on the fraction of circumstellar material that is hidden by Galactic contamination within our band or that is present on angular scales too large to be detected by the VLA. It appears that the bulk of the circumstellar gas has originated directly from the star, although it may be augmented by material swept from the surrounding ISM. The H I data are consistent with a stellar wind with an outflow velocity V [subscript o] = 35.6 ± 1.2 km s[superscript –1] and a mass-loss rate of [dot over M] ≈ (1.0 ± 0.8) x 10[superscript -6] M [subscript ʘ] yr[superscript –1]. We have computed theoretical evolutionary tracks that include mass loss across the instability strip and show that a mass-loss rate of this magnitude, sustained over the preceding Cepheid lifetime of δ Cephei, could be sufficient to resolve a significant fraction of the discrepancy between the pulsation and evolutionary masses for this star. National Science Foundation (U.S.) (Grant AST-1009644) 2015-02-20T20:07:56Z 2015-02-20T20:07:56Z 2011-12 2011-10 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/95470 Matthews, L. D., M. Marengo, N. R. Evans, and G. Bono. “NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 Cm LINE OBSERVATIONS.” The Astrophysical Journal 744, no. 1 (December 13, 2011): 53. © 2012 The American Astronomical Society en_US http://dx.doi.org/10.1088/0004-637x/744/1/53 The Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf IOP Publishing American Astronomical Society |
| spellingShingle | Marengo, Massimo Evans, N. R. Bono, G. Matthews, Lynn D. NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title | NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title_full | NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title_fullStr | NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title_full_unstemmed | NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title_short | NEW EVIDENCE FOR MASS LOSS FROM δ CEPHEI FROM H I 21 cm LINE OBSERVATIONS |
| title_sort | new evidence for mass loss from δ cephei from h i 21 cm line observations |
| url | http://hdl.handle.net/1721.1/95470 |
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