[vsnet-chat 3325] Re: LS 5039 - "galactic microquasar"?

[Taichi Kato <tkato>]

Re: LS 5039 - "galactic microquasar"?

> The description as a "galactic microquasar" is a contradiction. There is
> nothing micro about  a quasar, nor is any to be found close to plane of the
> Milky Way, like the stars in the LS catalogue.  Perhaps the term
> "microquasar', unsatisfactory as it is,
> was a quick short-hand way of describing some other phenomenon. If so, what
> is the phenomenon?  Further information is requested, please.

   Microquasars are a recently recognized category of compact binaries
(most likely black hole binaries) which have (mostly transient) ejection
of relativistic jets.  The velocity of jet can reach 0.3-0.9 c (c is the speed
of light).  Other terminology referring to this class of objects is
"galactic superluminal source", but the term "microquasar" is becoming
more popular.  The famous persisent source equivalent to this class is
SS 433 = V1343 Aql.  V4641 Sgr of the last year is also a member of
microquasars.  In the case of LS 5039, the discovery of radio jets has
revealed the microquasar nature, which will appear (as I have heard)
in the coming issue of Science.  Little is known about the optical
variability, but an optical flash as observed in V4641 Sgr may occur at
the time of the next jet ejection.

Regards,
Taichi Kato

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