The Influence of Rotation in Radiation‐driven Wind from Hot Stars: New Solutions and Disk Formation in Be Stars

Curé, M.

doi:10.1086/423776

Cited by 56 publications

(140 citation statements)

References 24 publications

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“…As was described in Curé (2004) and Curé et al (2011), the wind velocity profile is obtained by solving the radial component of the momentum equation at the equatorial plane,…”

Section: The Hydrodynamical Wind Modelmentioning

confidence: 99%

“…Besides the classical m-CAK solution (Friend & Abbott 1986;Pauldrach et al 1986), hereafter called thefast solution, Curé (2004) discovered the so-called Ω-slow solution for radiationdriven winds in stars rotating at speeds close to their critical (breakup) velocities, V crit , i.e., at Ω0.7-0.8, with Ω=V rot / V crit , where V rot is the rotation velocity at the starʼs equator. As compared with the fast solution, the Ω-slow solution leads to a dense and slow wind, characterized by a lower terminal velocity.…”

Section: Introductionmentioning

confidence: 99%

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The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Venero

Curé

Cidale

et al. 2016

ApJ

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In the scenario of rotating radiation-driven wind theory for massive stars, three types of stationary hydrodynamic solutions are currently known: the classical ( fast) m-CAK solution, the Ω-slow solution that arises for fast rotators, and the so-called δ-slow solution if high values of the δ line-force parameter are allowed independently of the rotation speed. Compared to the fast solution, both "slow solutions" have lower terminal velocities. As the study of the parameter domain for the slow solution is still incomplete, we perform a comprehensive analysis of the distinctive flow regimes for B supergiants that emerge from a fine grid of rotation values, Ω, and various ionization conditions in the wind(δ) parameter. The wind ionization defines two domains: one for fast outflowing winds and the other for slow expanding flows. Both domains are clear-cut by a gap, where a kink/plateau structure of the velocity law could exist for a finite interval of δ. The location and width of the gap depend on T eff and Ω. There is a smooth and continuous transition between the Ω-slow and δ-slow regimes, a single Ω δ-slow regime. We discuss different situations where the slow solutions can be found and the possibility of a switch between fast and slow solutions in B supergiant winds. We compare the theoretical terminal velocity with observations of B and A supergiants and find that the fast regime prevails mostly for early B supergiants while the slow wind regime matches better for A and B mid-and late-type supergiants.

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“…As was described in Curé (2004) and Curé et al (2011), the wind velocity profile is obtained by solving the radial component of the momentum equation at the equatorial plane,…”

Section: The Hydrodynamical Wind Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Venero

Curé

Cidale

et al. 2016

ApJ

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“…A possible scenario discussed in the literature to explain the formation of outflowing high-density disks in singlestar evolution is the bistability mechanism induced by rotation (Lamers & Pauldrach 1991;Pelupessy et al 2000). However, the density of these disks increases enormously when the slowwind solution (Curé 2004) at high rotation rates (Ω > 0.6) is considered (Curé et al 2005). In both, the rapid stellar rotation is an important prerequisite, but it is even more important to know if a massive main-sequence star could remain close to the limit of critical rotation for a substantial fraction of its lifetime (Langer 1998).…”

Section: Evolutionary Stage Of Gg Carmentioning

confidence: 99%

Molecular emission from GG Carinae’s circumbinary disk

Kraus

Oksala

Nickeler

et al. 2012

A&A

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Context. The appearance of the B[e] phenomenon in evolved massive stars such as B [e] supergiants is still a mystery. While these stars are generally found to have disks that are cool and dense enough for efficient molecule and dust condensation, the origin of the disk material is still unclear. Aims. We aim at studying the kinematics and origin of the disk in the eccentric binary system GG Car, whose primary component is proposed to be a B[e] supergiant. Methods. Based on medium-and high-resolution near-infrared spectra we analyzed the CO-band emission detected from GG Car. The complete CO-band structure delivers information on the density and temperature of the emitting region, and the detectable 13 CO bands allow us to constrain the evolutionary phase. In addition, the kinematics of the CO gas can be extracted from the shape of the first 12 CO band head. Results. We find that the CO gas is located in a ring surrounding the eccentric binary system, and its kinematics agrees with Keplerian rotation with a velocity, projected to the line of sight, of 80 ± 1 km s −1 . The CO ring has a column density of (5 ± 3) × 10 21 cm −2 and a temperature of 3200 ± 500 K. In addition, the material is chemically enriched in 13 C, which agrees with the primary component being slightly evolved off the main sequence. We discuss two possible scenarios for the origin of the circumbinary disk: (i) nonconservative Roche lobe overflow; and (ii) the possibility that the progenitor of the primary component could have been a classical Be star. Neither can be firmly excluded, but for Roche lobe overflow to occur, a combination of stellar and orbital parameter extrema would be required.

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“…B[e]SGs show various observational signatures of a dense circumstellar disk or ring, including narrow forbidden emission lines, molecular emission, and evidence for dust (for a general review see Lamers et al 1998). Zickgraf et al (1985) proposed a disk formation mechanism for B[e] stars, in which rapid rotation produces a hybrid wind consisting of a fast line-driven polar component and a slow, high density equatorial component (with further study by, e.g., Lamers & Pauldrach 1991;Pelupessy et al 2000;Kraus & Lamers 2003;Curé 2004;Curé & Rial 2004;Curé et al 2005;Kraus 2006). While the spectral features certainly support this process, rotational speeds have been determined for only a few B[e]SGs including LHA 115-S 23 (Kraus et al 2008), LHA 115-S 65 (Zickgraf 2000;Kraus et al 2010), LHA 120-S 93 (Gummersbach et al 1995), and LHA 120-S 73 (Zickgraf 2006).…”

Section: Introductionmentioning

confidence: 99%

Probing the ejecta of evolved massive stars in transition

Oksala

Kraus

Cidale

et al. 2013

A&A

139

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Massive evolved stars in transition phases, such as luminous blue variables (LBVs), B[e] supergiants (B[e]SGs), and yellow hypergiants (YHGs), are not well understood, and yet crucial steps in determining accurate stellar and galactic evolution models. The circumstellar environments of these stars reveal their mass-loss history, identifying clues to both their individual evolutionary status and the connection between objects of different phases. Here we present a survey of 25 such evolved massive stars (16 B[e]SGs, 6 LBVs, 2 YHGs, and 1 Peculiar Oe star), observed in the K-band with the Spectrograph for INtegral Field Observation in the Near-Infrared (SINFONI; R = 4500) on the ESO VLT UT4 8 m telescope. The sample can be split into two categories based on spectral morphology: one group includes all of the B[e]SGs, the Peculiar Oe star, and two of the LBVs, while the other includes the YHGs and the rest of the LBVs. The difference in LBV spectral appearance is due to some objects being in a quiescent phase and some objects being in an active or outburst phase. CO emission features are found in 13 of our targets, with first time detections for MWC 137, LHA 120-S 35, and LHA 115-S 65. From model fits to the CO band heads, the emitting regions appear to be detached from the stellar surface. Each star with 12 CO features also shows 13 CO emission, signaling an evolved nature. Based on the level of 13 C enrichment, we conclude that many of the B[e]SGs are likely in a pre-Red Supergiant phase of their evolution. There appears to be a lower luminosity limit of log L/L = 5.0 below which CO is not detected. The lack of CO features in several high luminosity B[e]SGs and variability in others suggests that they may in fact be LBV candidates, strengthening the connection between these two very similar transition phases.

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The Influence of Rotation in Radiation‐driven Wind from Hot Stars: New Solutions and Disk Formation in Be Stars

Cited by 56 publications

References 24 publications

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

The Wind of Rotating B Supergiants. I. Domains of Slow and Fast Solution Regimes

Molecular emission from GG Carinae’s circumbinary disk

Probing the ejecta of evolved massive stars in transition

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