[vsnet-alert 5312] Re: DELTA VELORUM IS AN ECLIPSING BINARY !!

[Sonja Vrielmann <sonja@pinguin.ast.uct.ac.za>]

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
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