The enigmatic binary system HD 5980
The Small Magellanic Cloud multiple system HD 5980 contains a luminous blue variable (LBV) that underwent a major eruption in 1994, and whose current spectrum is that of a hydrogen-rich Wolf–Rayet (WR) star. Since the eruption, the wind mass-loss rate has been declining while wind speeds have been s...
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| Autores principales: | , , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
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2019
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/123486 |
| Aporte de: |
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I19-R120-10915-123486 |
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dspace |
| institution |
Universidad Nacional de La Plata |
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I-19 |
| repository_str |
R-120 |
| collection |
SEDICI (UNLP) |
| language |
Inglés |
| topic |
Astronomía binaries: eclipsing stars: individual(HD 5980) stars: Wolf–Rayet stars: winds, outflows stars: mass-loss |
| spellingShingle |
Astronomía binaries: eclipsing stars: individual(HD 5980) stars: Wolf–Rayet stars: winds, outflows stars: mass-loss Hillier, D. J. Koenigsberger, Gloria Nazé, Yaël Morrell, Nidia Irene Barbá, Rodolfo Héctor Gamen, Roberto Claudio The enigmatic binary system HD 5980 |
| topic_facet |
Astronomía binaries: eclipsing stars: individual(HD 5980) stars: Wolf–Rayet stars: winds, outflows stars: mass-loss |
| description |
The Small Magellanic Cloud multiple system HD 5980 contains a luminous blue variable (LBV) that underwent a major eruption in 1994, and whose current spectrum is that of a hydrogen-rich Wolf–Rayet (WR) star. Since the eruption, the wind mass-loss rate has been declining while wind speeds have been steadily increasing. Observations obtained in 2014 when <i>Star A</i> (the LBV) eclipses <i>Star B</i> indicate that the fitted mass-loss rate and luminosity have reached the lowest values ever determined for such spectra: Ṁ = 4.5 × 10⁻⁵ M⊙ yr⁻¹, L = 1.7 × 10⁶ L⊙. In addition, the radius of the LBV’s continuum-emitting region is similar to that derived from the eclipse light curves of the late 1970s. Hence, it appears to have attained a similar ‘low’ state to that of the late 1970s. While a good fit to the emission spectrum is obtained using a cmfgen model, there are discrepancies in the UV. In particular, the extent of the observed absorption profiles is ∼1000 km s⁻¹ greater than predicted by the emission-line intensities. Further, <i>HST</i> UV observations obtained in 2016, when <i>Star A</i> is eclipsed by <i>Star B</i>, show unusual P Cygni profiles that are not easily explained. Surprisingly the 2016 emission-line spectrum is similar to that at the opposite eclipse obtained in 2014. The complex UV profiles are likely to arise as a consequence of the dynamics of the wind–wind collision and radiative braking, both of which will cause significant departures from spherical symmetry, and have a strong orbital phase dependence. However, other scenarios, such as intrinsically aspherical winds, cannot be ruled out. |
| format |
Articulo Articulo |
| author |
Hillier, D. J. Koenigsberger, Gloria Nazé, Yaël Morrell, Nidia Irene Barbá, Rodolfo Héctor Gamen, Roberto Claudio |
| author_facet |
Hillier, D. J. Koenigsberger, Gloria Nazé, Yaël Morrell, Nidia Irene Barbá, Rodolfo Héctor Gamen, Roberto Claudio |
| author_sort |
Hillier, D. J. |
| title |
The enigmatic binary system HD 5980 |
| title_short |
The enigmatic binary system HD 5980 |
| title_full |
The enigmatic binary system HD 5980 |
| title_fullStr |
The enigmatic binary system HD 5980 |
| title_full_unstemmed |
The enigmatic binary system HD 5980 |
| title_sort |
enigmatic binary system hd 5980 |
| publishDate |
2019 |
| url |
http://sedici.unlp.edu.ar/handle/10915/123486 |
| work_keys_str_mv |
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Repositorios |
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