As John pointed out, although the star is known as a triple system since a
long time, I think they are not referring to the star that causes the eclipses.
Of course we should find the paper, but even the "a" star was merely recognized
until recently.
The 'two A stars possibility' arose from the discrepance existing between
observed and predicted absolute magnitude for an A0/A1 star at delta Velorum's
distance (75 light years). MV should be 1.0 and not
0.4. Even including the "a" star, another A type star is needed
to fit the theory.
But it's true, they are also speculations. However, I don't think it
possible for a brown dwarf to induce a 0.3 magnitude drop in brightness in
a very luninous A type star (whatever the star of the system is). It should be a
very big brown dwarf!!
I don't know, it's just an opinion.
The 5.88854 day-period list of predictions only included times near the
67.7 day period because it would let us confirm which of the two peirods is
real. Anyway the star is in a very bad position these days for any kind of
observation to be made.
Regarding the coverage, it is complete, since there are observers in
Australia, New Zeland, South America and South Africa, so the next eclipses
won't be missed (providing the weather ...)
On November 1st, there will be another eclipse and probably you, South
African people will be the lucky ones to observe it.
Seabstian.
congratulations to your observations.
But I must unfortunately
disappoint you. This object is known to be a
binary system, see e.g.
Tokovinin, A.A., 1997 A&AS, 124,75
Tutukov, A. V. 1995, AZh, 72, 400
even claims it to be an eclipsing
planetary system or at least an eclipsing
binary with a brown dwarf.
I don't have the article here on hand to see what
orbital period Tutukov
found. Can anybody else help?
It is
nevertheless certainly worth while to observe this object further!
In
the listing of your eclipse timings for a period of 5.888 days, why do
you
only list every 11th eclipse time and not all? I would suggest to
observe
this object every night for a while, preferably several times per
night. The
eclipse is lasting (according to Tutukov) several hours. It
would be easier
if there are observers at different longitudes (i.e.
America, Europe/Africa,
Asia/Australia).
Anyway, your plot doesn't show a very regular 67 day
period, which means
the period must rather be the shorter (5.888) day
period.
You suggest that both component have the same spectral type,
because this
would make the detection harder. It is rather so that it would
have made
it much easier to see the companion spectroscopically. Even with
only one
spectrum it would have been most likely to catch the system at an
orbital
phase where the lines would be seperated, i.e. double. It is rather
an
indication that the compagnion is of (much) later spectral type and
(much)
fainter (e.g. a brown dwarf) and is therefore not seen
before.
Best
regards,
Sonja.
-------------------------------------------------*---------------------
Dr.
Sonja
Vrielmann
* *
Dept. of Astronomy, University of Cape
Town * *
Private Bag,
Rondebosch, 7701 Tel: +27-21-650-4042, Fax:
-3352
South
Africa
Email:
sonja@pinguin.ast.uct.ac.za-----------------------------------------------------------------------
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