Review: <i>Spencer Baird of the Smithsonian</i>, by E. F. Rivinius and E. M. Youssef

Porter, Charlotte M.

doi:10.2307/3378599

Cited by 93 publications

(123 citation statements)

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“…If these stars correspond to Be stars as suggested by Keller et al (2002), then the competing mechanisms are mass loss through stellar winds, rapid rotation or non-radial pulsations, or a combination of these. These mechanisms are usually invoked for disc formation and outbursts in Be stars (see Porter & Rivinius 2003, for a review of the Be star phenomenon). In this context, it is interesting that recent work suggests that rapid rotation (and eventually rotationally induced mass loss) is favoured in low metallicity environments.…”

Section: O N C L U S I O N Smentioning

confidence: 99%

Be star candidates in the Large Magellanic Cloud: the catalogue and comparison with the Small Magellanic Cloud sample

Sabogal

Mennickent

Pietrzyński

et al. 2005

Monthly Notices of the Royal Astronomical Society

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We present a catalogue with coordinates and photometric data of 2446 Be star candidates in the Large Magellanic Cloud (LMC), based on a search of the OGLE II data base. The I‐band light curves of these stars show outbursts in 24 per cent of the sample (Type‐1 stars), high and low states in 10 per cent, periodic variations in 6 per cent (Type‐3 stars), and stochastic variations in 60 per cent of the cases. We report on the result of the statistical study of light curves of Type‐1 and Type‐3 stars in the LMC, and the comparison with the previously reported results of the Small Magellanic Cloud (SMC) sample. We find a statistically significant difference between amplitude, duration and asymmetry distributions of outbursts in both galaxies. Outbursts of SMC Type‐1 stars are usually brighter, longer and with a slower decline. We find a bimodal distribution of periods of Type‐3 stars in both galaxies, probably related to the recently discovered double periodic blue variables. We find also period and amplitude distributions of Type‐3 LMC stars statistically different from those of the SMC stars. Our findings above suggest that the mechanisms causing the observed photometric variability of Type‐1 and Type‐3 stars could depend on metallicity. Moreover, they suggest that the outbursts are not primarily caused by stellar winds.

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Section: O N C L U S I O N Smentioning

confidence: 99%

Be star candidates in the Large Magellanic Cloud: the catalogue and comparison with the Small Magellanic Cloud sample

Sabogal

Mennickent

Pietrzyński

et al. 2005

Monthly Notices of the Royal Astronomical Society

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“…Be stars are young and hot, with spectral type B (or O) characterized by Balmer emission lines thought to be associated with circumstellar material shed due to the rapid rotation of the star, which may be near its disruption speed (see e.g. Porter & Rivinius 2003). The NS, in an elliptical orbit around the star, can accrete matter from an equatorial 'decretion disc' that may be formed from the disrupted material, or from a strong stellar wind; this potentially leads to outbursts in X-rays seen at different orbital phases.…”

Section: Introductionmentioning

confidence: 99%

The accretion powered spin-up of GRO J1750−27

Shaw¹,

Hill²,

Kuulkers³

et al. 2009

Monthly Notices of the Royal Astronomical Society

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The timing properties of the 4.45 s pulsar in the Be X‐ray binary system GRO J1750−27 are examined using hard X‐ray data from INTEGRAL and Swift during a type II outburst observed during 2008. The orbital parameters of the system are measured and agree well with those found during the last known outburst of the system in 1995. Correcting the effects of the Doppler shifting of the period, due to the orbital motion of the pulsar, leads to the detection of an intrinsic spin‐up that is well described by a simple model including and terms of −7.5 × 10−10 s s−1 and 1 × 10−16 s s−2, respectively. The model is then used to compare the time‐resolved variation of the X‐ray flux and intrinsic spin‐up against the accretion torque model of Ghosh & Lamb; this finds that GRO J1750−27 is likely located 12–22 kpc distant and that the surface magnetic field of the neutron star is ∼2 × 1012 G. The shape of the pulse and the pulsed fraction shows different behaviour above and below 20 keV, indicating that the observed pulsations are the convolution of many complex components.

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“…Since Struve's model, there have been several dynamical models presented in attempt to explain the existence and maintenance of the circumstellar envelopes of Be stars (see the review by Porter & Rivinius 2003). Recent work has concentrated on wind compressed discs (see e.g.…”

Section: Introductionmentioning

confidence: 99%

The circumstellar envelopes of Be stars: viscous disc dynamics

Jones

Sigut

Porter

2008

Monthly Notices RAS

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We have constructed models of axisymmetric, circumstellar envelopes for Be star discs by successfully combining two numerical codes: a non‐local thermodynamic equilibrium (non‐LTE) radiative transfer code which calculates the level populations and disc temperature distribution self‐consistently, and a hydrodynamical code. The output of one code is used as input to the other code, and hence evolving density and thermal structures may be examined. The temperatures, disc density and velocity distribution are used to investigate the outflowing viscous disc model for Be stars. We find that these simulations place constraints on the power‐law density decrease in the disc with increasing distance from the star. We find that the power‐law index for the line‐forming region of the disc lies between 3 and 3.5 with a small dispersion.

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Review: Spencer Baird of the Smithsonian, by E. F. Rivinius and E. M. Youssef

Cited by 93 publications

References 0 publications

Be star candidates in the Large Magellanic Cloud: the catalogue and comparison with the Small Magellanic Cloud sample

Be star candidates in the Large Magellanic Cloud: the catalogue and comparison with the Small Magellanic Cloud sample

The accretion powered spin-up of GRO J1750−27

The circumstellar envelopes of Be stars: viscous disc dynamics

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