* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Home -> Astronomy News -> Stars -> SS Leporis
Post Info TOPIC: SS Leporis
Blobrana


L

Posts: 131433
Date:
RE: SS Leporis
Permalink  
 

Title: An incisive look at the symbiotic star SS Leporis -- Milli-arcsecond imaging with PIONIER/VLTI
Authors: N. Blind, H. M. J. Boffin, J.-P. Berger, J.-B. Le Bouquin, A. Mérand, B. Lazareff, G. Zins

Context. Determining the mass transfer in a close binary system is of prime importance for understanding its evolution. SS Leporis, a symbiotic star showing the Algol paradox and presenting clear evidence of ongoing mass transfer, in which the donor has been thought to fill its Roche lobe, is a target particularly suited to this kind of study.
Aims. Since previous spectroscopic and interferometric observations have not been able to fully constrain the system morphology and characteristics, we go one step further to determine its orbital parameters, for which we need new interferometric observations directly probing the inner parts of the system with a much higher number of spatial frequencies.
Methods. We use data obtained at eight different epochs with the VLTI instruments AMBER and PIONIER in the H- and K-bands. We performed aperture synthesis imaging to obtain the first model-independent view of this system. We then modelled it as a binary (whose giant is spatially resolved) that is surrounded by a circumbinary disc.
Results. Combining these interferometric measurements with previous radial velocities, we fully constrain the orbit of the system. We then determine the mass of each star and significantly revise the mass ratio. The M giant also appears to be almost twice smaller than previously thought. Additionally, the low spectral resolution of the data allows the flux of both stars and of the dusty disc to be determined along the H and K bands, and thereby extracting their temperatures.
Conclusions. We find that the M giant actually does not stricto sensus fill its Roche lobe. The mass transfer is more likely to occur through the accretion of an important part of the giant wind. We finally rise the possibility for an enhanced mass loss from the giant, and we show that an accretion disc should have formed around the A star.

Read more (2506kb, PDF)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Vampire Star Reveals its Secrets

eso1148a.jpg

Astronomers have obtained the best images ever of a star that has lost most of its material to a vampire companion. By combining the light captured by four telescopes at ESO's Paranal Observatory they created a virtual telescope 130 metres across with vision 50 times sharper than the NASA/ESA Hubble Space Telescope. Surprisingly, the new results show that the transfer of mass from one star to the other in this double system is gentler than expected.
The astronomers observed the unusual system SS Leporis in the constellation of Lepus (The Hare), which contains two stars that circle around each other in 260 days. The stars are separated by only a little more than the distance between the Sun and the Earth, while the largest and coolest of the two stars extends to one quarter of this distance - corresponding roughly to the orbit of Mercury. Because of this closeness, the hot companion has already cannibalised about half of the mass of the larger star.
Read more 



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: An incisive look at the symbiotic star SS Leporis. Milli-arcsecond imaging with PIONIER/VLTI
Authors: N. Blind, H.M.J. Boffin, J.-P. Berger, J.-B. Le Bouquin, A. Mérand, B. Lazareff, G. Zins

Read more (Subscription)



__________________
Blobrana


L

Posts: 131433
Date:
Permalink  
 

Title: A PIONIER and incisive look at the interacting binary SS Lep
Authors: N. Blind, H.M.J. Boffin, J.-P. Berger, J.-B. Lebouquin, A. Mérand

Symbiotic stars are excellent laboratories to study a broad range of poorly understood physical processes, such as mass loss of red giants, accretion onto compact objects, and evolution of nova-like outbursts. As their evolution is strongly influenced by the mass transfer episodes, understanding the history of these systems requires foremost to determine which process is at play: Roche lobe overflow, stellar wind accretion, or some more complex mixture of both. We report here an interferometric study of the symbiotic system SS Leporis, performed with the unique PIONIER instrument. By determining the binary orbit and revisiting the parameters of the two stars, we show that the giant does not fill its Roche lobe, and that the mass transfer most likely occurs via the accretion of an important part of the giant's wind.

Read more  (180kb, PDF)



__________________
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.
Home -> Astronomy News -> Stars -> SS Leporis


Create your own FREE Forum
Report Abuse 		Powered by ActiveBoard