Geometry and physical conditions in the stellar wind of AG Carinae

Leitherer, Claus; Allen, Richard G.; Altner, B.; Damineli, A.; Drissen, Laurent; Idiart, T. P.; Lupie, O. L.; Nota, A.; Robert, Carmelle; Schmutz, W.; Shore, Steven N.

doi:10.1086/174241

Cited by 65 publications

(101 citation statements)

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“…On the other hand, the FWHMs of the broad Hβ and Hα emission lines in the SDSS spectrum, ∼1000 km s −1 , are higher than those in the VLT/UVES spectrum but are similar to the values derived from the VLT/X-shooter spectrum. Despite these differences, all FWHMs of the broad lines in the spectra of PHL 293B are significantly broader than those observed in the spectra of high-metallicity LBVs which are about 100-200 km s −1 (e.g., Leitherer et al 1994). However, they are similar to the FWHMs in some extragalactic LBVs during their outburst phase Izotov & Thuan (2009).…”

Section: Reportedmentioning

confidence: 71%

VLT/X-shooter observations of the low-metallicity blue compact dwarf galaxy PHL 293B including a luminous blue variable star

Izotov¹,

Гусева²,

Fricke³

et al. 2011

A&A

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Context. We present VLT/X-shooter spectroscopic observations in the wavelength range λλ3000-23 000 Å of the extremely metaldeficient blue compact dwarf (BCD) galaxy PHL 293B containing a luminous blue variable (LBV) star and compare them with previous data. Aims. This BCD is one of the two lowest-metallicity galaxies where LBV stars were detected, allowing us to study the LBV phenomenon in the extremely low metallicity regime. Methods. We determine abundances of nitrogen, oxygen, neon, sulfur, argon, and iron by analyzing the fluxes of narrow components of the emission lines using empirical methods and study the properties of the LBV from the fluxes and widths of broad emission lines. Results. We derive an interstellar oxygen abundance of 12+log O/H = 7.71 ± 0.02, which is in agreement with previous determinations. The observed fluxes of narrow Balmer, Paschen and Brackett hydrogen lines correspond to the theoretical recombination values after correction for extinction with a single value C(Hβ) = 0.225. This implies that the star-forming region observed in the optical range is the only source of ionisation and there is no additional source of ionisation that is seen in the NIR range but is hidden in the optical range. We detect three v = 1-0 vibrational lines of molecular hydrogen. Their flux ratios and non-detection of v = 2-1 and 3-1 emission lines suggest that collisional excitation is the main source producing H 2 lines. For the LBV star in PHL 293B we find broad emission with P Cygni profiles in several Balmer hydrogen emission lines and for the first time in several Paschen hydrogen lines and in several He i emission lines, implying temporal evolution of the LBV on a time scale of 8 years. The Hα luminosity of the LBV star is by one order of magnitude higher than the one obtained for the LBV star in NGC 2363≡Mrk 71 which has a slightly higher metallicity 12+logO/H = 7.87. The terminal velocity of the stellar wind in the low-metallicity LBV of PHL293B is high, ∼800 km s −1 , and is comparable to that seen in spectra of some extragalactic LBVs during outbursts. We find that the averaged terminal velocities derived from the Paschen and He i emission lines are by some ∼40-60 km s −1 lower than those derived from the Balmer emission lines. This probably indicates the presence of the wind accelerating outward.

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Section: Reportedmentioning

confidence: 71%

VLT/X-shooter observations of the low-metallicity blue compact dwarf galaxy PHL 293B including a luminous blue variable star

Izotov¹,

Гусева²,

Fricke³

et al. 2011

A&A

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“…Contrary to former beliefs, a positive correlation between the brightness variation due to the SD-phases and the mass loss rate appeared to be not always true (Leitherer et al 1989(Leitherer et al , 1994de Koter et al 1996). Whetheṙ M increases or decreases during an SD-phase depends on the temperature change, the proximity to the Atmospheric Eddington Limit (AEL, Lamers 1997), and the bistability jumps (Pauldrach & Puls 1990;Lamers 1997).…”

Section: The S Dor (Sd)-phasesmentioning

confidence: 80%

S Doradus variables in the Galaxy and the Magellanic Clouds

Genderen¹

2001

A&A

196

105

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Abstract. The goal in writing this paper is five fold: (1) to summarize the scientific achievements in the 20th century on S Dor variables (or LBVs); (2) to present an inventory of these variables in the Galaxy and the Magellanic Clouds with a description of their physical state and instability properties; (3) to emphasize the photometric achievements of the various types of instabilities. Generally this seems to be a neglected item resulting in a number of misunderstandings continuously wandering through literature; (4) to investigate the structure of the S Dor-area on the HR-diagram; (5) to estimate the total numbers of S Dor variables in the three stellar systems. The position of the strong active S Dor variables in minimum brightness obey the following linear relation on the HR-diagram:log L/L = 1.37 log T eff − 0.03. The relatively small dispersion of less active and supposed exand dormant S Dor variables with respect to this relation is twice as large at the blue side than at the red side. This might be caused by evolution to the WR stage and/or to high rotation. S Dor variables can be subject to five types of instabilities: the very rare genuine eruptive episodes (the "SD-eruptions"), two different brightening phases caused by slow pulsations (the "SD-phases"): one on a time scale of years, the other on a time scale of decades at a more or less constant luminosity and two types of microvariations: one on a time scale of weeks, the other on a time scale of about 100 d. So far, no periodicities of light curve characteristics of any of these instabilities have ever been found. The durations of active and non-active stages are estimated for about half of the sample based on scattered magnitude estimations such as from historical records, and on modern monitoring campaigns. It would be a misunderstanding to believe that all S Dor variables should be always spectacular. It is estimated that most of them will not be spectacular at all for at least 70% of their lifetime as an S Dor variable.

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“…Following the criteria from Crowther et al (1995), the presence of H, the N ii lines being stronger than those of N iii, and the presence of He ii λ4686 indicate a WN11h classification. Indeed, the non-rotating 25 M model spectrum is similar to that of the LBV AG Carinae at visual minimum (1989 June), when it had a WN11h spectral type (Smith et al 1994;Leitherer et al 1994;Stahl et al 2001;Groh et al 2009b). The main difference is that the model spectrum has broader lines, since its υ ∞ = 694 km s −1 is about twice that of AG Car in 1989 June (300 km s −1 , Groh et al 2009b).…”

Section: Spectra and Spectral Type Classification Of Sn Progenitorsmentioning

confidence: 91%

Fundamental properties of core-collapse supernova and GRB progenitors: predicting the look of massive stars before death

Groh

Meynet

Georgy

et al. 2013

A&A

193

223

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We investigate the fundamental properties of core-collapse supernova (SN) progenitors from single stars at solar metallicity. For this purpose, we combine Geneva stellar evolutionary models with initial masses of M ini = 20−120 M with atmospheric and wind models using the radiative transfer code CMFGEN. We provide synthetic photometry and high-resolution spectra of hot stars at the pre-SN stage. For models with M ini = 9−20 M , we supplement our analysis using publicly available MARCS model atmospheres of RSGs to estimate their synthetic photometry. We employ well-established observational criteria of spectroscopic classification and find that, depending on their initial mass and rotation, massive stars end their lives as red supergiants (RSG), yellow hypergiants (YHG), luminous blue variables (LBV), and Wolf-Rayet (WR) stars of the WN and WO spectral types. For rotating models, we obtained the following types of SN progenitors:, and RSGs (9 ≤ M ini ≤ 18 M ). For non-rotating models, we found spectral types WO1-, and RSGs (9 ≤ M ini ≤ 20 M ). Our rotating models indicate that SN IIP progenitors are all RSG, SN IIL/b progenitors are 56% LBVs and 44% YHGs, SN Ib progenitors are 96% WN10-11 and 4% WOs, and SN Ic progenitors are all WO stars. We find that the most massive and luminous SN progenitors are not necessarily the brightest ones in a given filter, since this depends on their luminosity, temperature, wind density, and the way the spectral energy distribution compares to a filter bandpass. We find that SN IIP progenitors (RSGs) are bright in the RIJHK S filters and faint in the UB filters. SN IIL/b progenitors (LBVs and YHGs), and SN Ib progenitors (WNs) are relatively bright in optical/infrared filters, while SN Ic progenitors (WOs) are faint in all optical filters. We argue that SN Ib and Ic progenitors from single stars should be undetectable in the available pre-explosion images with the current magnitude limits, in agreement with observational results.

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Geometry and physical conditions in the stellar wind of AG Carinae

Cited by 65 publications

References 0 publications

VLT/X-shooter observations of the low-metallicity blue compact dwarf galaxy PHL 293B including a luminous blue variable star

VLT/X-shooter observations of the low-metallicity blue compact dwarf galaxy PHL 293B including a luminous blue variable star

S Doradus variables in the Galaxy and the Magellanic Clouds

Fundamental properties of core-collapse supernova and GRB progenitors: predicting the look of massive stars before death

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