Evolution of a Rotating Star of Nine Solar Masses

Kippenhahn, Rudolf; Meyer-Hofmeister, E.; Thomas, H. C.

doi:10.1007/978-94-010-3299-5_8

Cited by 86 publications

(100 citation statements)

References 2 publications

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“…Although M8E-IR cannot straightforwardly be identified with corresponding very early evolutionary stages, the tendency for a bloated central star in the case of M8E-IR may be valid. As found already by Kippenhahn & Meyer-Hofmeister (1977), accretion with high rates onto main sequence stars can temporarily puff up such stars. Furthermore, Hosokawa & Omukai (2008) and Yorke & Bodenheimer (2008) have recently computed the pre-main-sequence evolution of stars as a function of the accretion rate onto the forming star.…”

Section: Feasibility Of a Cool Central Objectsupporting

confidence: 58%

Mid-infrared interferometry of massive young stellar objects

Linz

Henning

Feldt

et al. 2009

A&A

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Context. Our knowledge of the inner structure of embedded massive young stellar objects is still quite limited. Thus, it is difficult to decide to what extent the mass accumulation onto forming massive stars differs from the process of low-mass star formation. Aims. We attempt to overcome the spatial resolution limitations of conventional thermal infrared imaging. Methods. We employed mid-infrared interferometry using the MIDI instrument on the ESO/VLTI facility to investigate M8E-IR, a well-known massive young stellar object suspected of containing a circumstellar disk. Spectrally dispersed visibilities in the 8-13 μm range have been obtained at seven interferometric baselines. Results. We resolve the mid-infrared emission of M8E-IR and find typical sizes of the emission regions of the order of 30 milliarcseconds ( =45 AU). Radiative transfer simulations were performed to interpret the data. The fitting of the spectral energy distribution, in combination with the measured visibilities, does not provide evidence for an extended circumstellar disk with sizes > ∼ 100 AU but requires the presence of an extended envelope. The data are not able to constrain the presence of a small-scale disk in addition to an envelope. In either case, the interferometry measurements indicate the existence of a strongly bloated, relatively cool central object, possibly tracing the recent accretion history of M8E-IR. In addition, we present 24.5 μm images that clearly distinguish between M8E-IR and the neighbouring ultracompact Hii region and which show the cometary-shaped infrared morphology of the latter source. Conclusions. Our results show that IR interferometry, combined with radiative transfer modelling, can be a viable tool to reveal crucial structure information on embedded massive young stellar objects and to resolve ambiguities arising from fitting the SED.

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Section: Feasibility Of a Cool Central Objectsupporting

confidence: 58%

Mid-infrared interferometry of massive young stellar objects

Linz

Henning

Feldt

et al. 2009

A&A

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“…In all cases, the tracks span the early AGB and stop at the first thermal pulse. a radiative envelope: Kippenhahn & Meyer-Hofmeister 1977;Jorissen 2003a, or when the WD accretion rate is large enough to trigger shell H-burning: Paczyński & Rudak 1980;Iben & Tutukov 1996). The post-AGB stars in those systems would thus be the analogs of the A-type companion of SS Lep.…”

Section: Relation With Post-agb Starsmentioning

confidence: 99%

Spectroscopic binaries among Hipparcos M giants

Jorissen¹,

Frankowski²,

Famaey³

et al. 2009

A&A

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Context. This paper is the third one in a series devoted to studying the properties of binaries involving M giants. Aims. We use a new set of orbits to construct the first (e − log P) diagram of an extensive sample of M giant binaries, to obtain their mass-function distribution, and to derive evolutionary constraints for this class of binaries and related systems. Methods. The orbital properties of binaries involving M giants were analysed and compared with those of related families of binaries (K giants, post-AGB stars, barium stars, Tc-poor S stars). Results. The orbital elements of post-AGB stars and M giants are not very different, which may indicate that, for the considered sample of post-AGB binaries, the post-AGB star left the AGB at quite an early stage (M4 or so). Neither are the orbital elements of post-mass-transfer binaries like barium stars very different from those of M giants, suggesting that the mass transfer did not alter the orbital elements much, contrary to current belief. Finally, we show that binary systems with e < 0.4 log P − 1 (with periods expressed in days) are predominantly post-mass-transfer systems, because (i) the vast majority of barium and S systems match this condition; and (ii) these systems have companion masses peaking around 0.6 M , as expected for white dwarfs. The latter property has been shown to hold as well for open-cluster binaries involving K giants, for which a lower bound on the companion mass may easily be set.

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“…The reason lies in the centrifugal force reducing the effective gravity at the stellar envelope. The luminosity and surface temperature there decrease (Kippenhahn 1977;Langer 1998;. Thus, the shell source becomes cooler, thinner, and more degenerated as the He core mass increases.…”

Section: Results Of Numerical Calculationmentioning

confidence: 98%

Structure and evolution of rotationally and tidally distorted stars

Song

Zhong

Lü

2009

A&A

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Aims. This paper aims to study the configuration of two components caused by rotational and tidal distortions in the model of a binary system. Methods. The potentials of the two distorted components can be approximated to 2nd-degree harmonics. Furthermore, both the accretion luminosity (σ i ) and the irradiative luminosity are included in stellar structure equations. Results. The equilibrium structure of rotationally and tidally distorted star is exactly a triaxial ellipsoids. A formula describing the isobars is presented, and the rotational velocity and the gravitational acceleration at the primary surface simulated. The results show the distortion at the outer layers of the primary increases with temporal variation and system evolution. Besides, it was observed that the luminosity accretion is unstable, and the curve of the energy-generation rate fluctuates after the main sequence in rotation sequences. The luminosity in rotation sequences is slightly weaker than that in non-rotation sequences. As a result, the volume expands slowly. Polar ejection is intensified by the tidal effect. The ejection of an equatorial ring may be favoured by both the opacity effect and the g e (θ, ϕ)-effect in the binary system.

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Evolution of a Rotating Star of Nine Solar Masses

Cited by 86 publications

References 2 publications

Mid-infrared interferometry of massive young stellar objects

Mid-infrared interferometry of massive young stellar objects

Spectroscopic binaries among Hipparcos M giants

Structure and evolution of rotationally and tidally distorted stars

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