Mass outflow in the nearby proto-planetary system, Beta Pictoris

Bruhweiler, F. C.; Grady, C. A.; Kondo, Y.

doi:10.1086/185994

Cited by 15 publications

(9 citation statements)

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“…For a velocity of a few tens of kilometer per second, corresponding to the thermal speed for the adopted temperature, we obtained: M ≈ 2.5 × 10 −14 M yr −1 . This value is consistent with the theoretical work of Babel (1995) on the mass loss rates of mainsequence A-type stars and with the observations of Bruhweiler et al (1991) on β Pictoris. It is also compatible with what was found by Beust et al (2001), when studying the interaction between an outflowing wind and infalling evaporating cometary bodies.…”

Section: Density Structuresupporting

confidence: 92%

A chromospheric scenario for the activity ofβ Pictoris, as revealed by FUSE

Bouret¹,

Deleuil²,

Lanz³

et al. 2002

A&A

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Abstract. We investigate a chromospheric scenario to explain the characteristics of the far-UV emission lines of β Pictoris, revealed by FUSE spectra of this famous circumstellar disk system. The model assumes a thin region heated up to a few 10 5 K located close to the stellar photosphere. The resonance lines of C III at 977 Å and O VI at 1032-1037 Å, seen in emission, are produced in this chromosphere-transition region complex. Using complementary data in the mid and near UV (specifically, a resonance doublet of C IV at 1548-1550 Å and Mg II h & k), we show that the whole dataset is remarquably well reproduced by the model. In addition, we investigate the properties of the C III* multiplet at 1176 Å and conclude that this line likely forms in a weak warm wind, originating from the prominent circumstellar disk of β Pictoris. Finally, radiative losses have been calculated and have provided estimates of the amount of non radiative energy dissipated in the external atmosphere of β Pictoris, which is a measure of the star's activity level. Such behavior for an A5 V star presents a challenge for both evolution and activity models since the former predict that main-sequence A stars should not be active, while the latter are unable to quantitatively account for the characteristics of the chromospheric heating of β Pictoris.

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Section: Density Structuresupporting

confidence: 92%

A chromospheric scenario for the activity ofβ Pictoris, as revealed by FUSE

Bouret¹,

Deleuil²,

Lanz³

et al. 2002

A&A

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“…Assuming Q = 1.5×10 4 Z, we obtained (2 × 10 −13 M /yr) for Sirius A. This assumption is also in a good agreement with the mass loss rate estimated for β Piċ M 1.1 × 10 −14 M /yr (Bruhweiler et al 1991), where our calculation givesṀ = 10 −14 M /yr. The CAK wind velocity law is given by…”

Section: Interaction With the Windsupporting

confidence: 89%

“…This may be related to the fact that there are no direct observational measurements for mass loss rates in main sequence A-type stars. The upper limits derived from the observations (Brown et al 1990;Lanz & Catala 1992) are 2-3 orders of magnitude above very few estimations (Bruhweiler et al 1991;Bertin et al 1995) we have for such stars.…”

Section: Interaction With the Windsupporting

confidence: 40%

Search for exoplanets and brown dwarfs with VLBI

Gawroński

Goździewski

2016

Mon. Not. R. Astron. Soc.

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The main aim of this work is to estimate possible radio GHz emission of extrasolar planets and brown dwarfs and to check if such radiation can be detected by Very Large Baseline Interferometers (VLBI). In the estimation we assume that the emission may originate in processes similar to those observed in the Jupiter system. The frequency of the radio emission that is produced in this system depends mostly on the magnetic field strength. Jupiter's magnetic field (∼ 9 G on average) allows for radiation from kHz frequencies up to 40 MHz. This is well below the frequency range of VLBI. However, it was demonstrated that the magnetic field strength in massive and young object may be up to two orders of magnitude higher than for Jupiter, which is especially relevant for planets around short-lived A type stars. This should extend the range of the emission up to GHz frequencies. We calculated expected flux densities of radio emission for a variety of hypothetical young planetary systems. We analysed two different emission scenarios, and found that the radiation induced by moons (process similar to Jupiter-Io interactions) appears to be less efficient than the emission generated by a stellar wind on a planetary magnetosphere. We also estimated hypothetical emission of planets and brown dwarfs located around relatively young and massive main sequence A-type stars. Our results show that the emission produced by stellar winds could be detected by currently operating VLBI networks.

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“…In Lagrange-Henri et al (1992), two weak blueshifted components were reported, and similar features are also observed in some (unpublished) data taken in 1996, with blueshifts reaching almost −100 km s −1 . Blueshifted components were also marginally identified in Fe II lines with the IUE satellite by Bruhweiler et al (1991). Therefore, the 1997 blueshifted events should just be considered as the strongest ever observed in the β Pic spectrum.…”

Section: Blueshifted Eventsmentioning

confidence: 96%