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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.
Best regards,
Seabstian.
Dear Sebastian
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 ----------------------------------------------------------------------- _______________________________________________ aavso-discussion mailing list aavso-discussion@mailman.McMaster.CA http://mailman.McMaster.CA/mailman/listinfo/aavso-discussion |
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