A horde of brown dwarf secondaries in cataclysmic binary systems?

View previous topic View next topic Go down

A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Edasich on 28th November 2008, 8:33 am

According to The Donor Stars of Cataclysmic Variables, yes. Here I see most of CV secondaries being much below stellar/substellar limit (even <<0.05 MSol).

Am I wrong?

Radii, as expected look a bit "bloated" (>>1.5 Rj) due to extreme heating and closeness to degenerate host.
Others seem Jupiter-sized.

An example:

DI UMa has a 0.051 MSol companion with radius 0.105 RSol (i.e 1.05 Jupiter radii). I think.
EG Cnc's secondary is even less massive (31 Mj) and Saturn-sized (0.95 Rj).

More details in the papers.
avatar
Edasich
dM star
dM star

Number of posts : 1509
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Sirius_Alpha on 28th November 2008, 1:52 pm

Edasich wrote:... Saturn-sized 0.95 Rj
Saturn's radius is 0.84 Rj. 0.95 Rj is much closer to Jupiter.

This is an interesting paper. What are the odds of a catacysmic variable star's secondary/donor being a planet?

How much of an influence can a planet have on its star?

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3456
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Lazarus on 28th November 2008, 5:55 pm

Given the nature of CV systems, I'm not sure that calling these objects "brown dwarfs" is a particularly helpful way to describe the system, unless you can show that the object was in the substellar regime before the onset of mass transfer.
avatar
Lazarus
dG star
dG star

Number of posts : 2808
Registration date : 2008-06-12

View user profile

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Edasich on 29th November 2008, 9:05 am

Ok, but when a low-mass stellar object has lost so much mass to lay in substellar regime and to stop any kind of stellar process, how should we call this object? Surely it could be an "exotic" kind.
avatar
Edasich
dM star
dM star

Number of posts : 1509
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Sirius_Alpha on 29th November 2008, 1:32 pm

It wouldn't be any different than what we find at the SWIFT J1756.9-2508 system, where a pulsar has accreted enough matter from a white dwarf to make the star a 7 Jupiter-mass object.

The object is still considered a star. It seems that what is, and what is not, a planet is considered to be related to how the object formed. The white dwarf at SWIFT J1756.9-2508 and the brown dwarfs at these CV systems may have both been stars, and as such, will probably continue to be considered as such.

_________________
Caps Lock: Cruise control for 'Cool'!
avatar
Sirius_Alpha
Admin
Admin

Number of posts : 3456
Location : Earth
Registration date : 2008-04-06

View user profile http://solar-flux.forumandco.com/

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Edasich on 29th November 2008, 1:45 pm

Surely "exotic" stars since they cannot burn hydrogen. Only being warmed and ionized due to extreme stellar closeness.

Interesting the fact often such objects do behave like Upsilon Andromedae b, showing dayside warmed and nightside quite cooler.

I've noticed this in this paper concerning LY Aquarii detached system where secondary is an object with 27 Jupiter masses and 0.6 Jupiter radii.

Orbital variability of the PSR J2051-0827 Binary System

Or else this other case:

A Brown Dwarf Companion for the Accreting Millisecond Pulsar SAX J1808.4-3658
avatar
Edasich
dM star
dM star

Number of posts : 1509
Location : Tau Ceti g - Mid Latitudes
Registration date : 2008-06-02

View user profile

Back to top Go down

Re: A horde of brown dwarf secondaries in cataclysmic binary systems?

Post by Sponsored content


Sponsored content


Back to top Go down

View previous topic View next topic Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum