[vsnet-alert 5313] re Delta Velorum eclipse "history"

[crawl@zoom.co.uk]

Dear Dr Sonja Vrielmann

As the one who checked Tokovinin's 1997 work and thoroughly failed to find
any mention of an eclipser in delta Velorum, could you kindly help with the
following:

There is no online access to this paper as yet, and I'm limited to online
resources for references, but I do have the tabular data via the CDS
journal tables' archive, which I had checked, and there is no mention of
any other star besides APCD, and the total number of objects is listed as 4.

Aa is TNG1 according to WDS2000, and according to the 1979 discovery paper
Sebastian notes in his post, is around 0.6" apart and with a period of "a
few decades".

AB is Innes 10, but Tokovinin appears not to include B for some reason.

CD is hj 4136 [John Herschel 4136].

I've checked all the separations to confirm this, and have now just noted
that Tokovinin _does not_ mention the Aa pair... ...his AP is actually
AB!!!!  Thus Tokovinin only tabulates an ABCD group, with no note on a.

So, I'm confused now, or rather I'm not confused, because I can find no
data re the 0.6"-0.7" speckle component in the tabular data.  However, as I
say, I have not got the body of the text to refer to.

Nor, like yourself, do I have any access to AZh papers.

Doing an independent check using the Bright Star Catalogue, this is
commonly thought of as an AB CD system, and most people don't know about Aa.

Now, re the nature of the companion.  I too at first thought it may be a
red or brown dwarf or even planetary detection, ie more of a transit than
an eclipse!  But I wondered why no molecular bands were evident in the
specrum if a late type star was involved, and thought a planetry object
just too good to be true!  However, I'm interested to see the idea
mentioned. delta Velorum is an infra-red excess IRAS source, but as it is
also in the ROSAT Bright Star Catalogue, I had simply presumed this to be
due to circumstellar matter.  However, I suppose a late type dwarf or brown
dwarf could fit the bill, with the xrays being of chromospheric or coronal
origin: it is not noted as being xray variable in the latest version of the
RASS PSPC mind.

Re Spectrum: Houk in her MHD catalogue lists it as overexposed, and lists
an "unpublished" type from "Garrison and Hagen", so that too is inaccessible.

But we must note that the AB pair are separated by just over 2 arcsecs, and
the Aa pair by less than 1 arcsec, that Aa-B are about 3 mags different and
and A-a about 1.3 mags different.

I am not sure if a clean spectrum is going to be found here anyway...
...definitely not on objective prism work.  IMPORTANT... ...Sebastian has
termed the eclipser 'x' in an attempt to avoid confusion.  'x' is _not_
'a'.  The previously known system was AaBCD.  None of these can give a
suitable eclipsing period.

Anyway, that's how I have the data at present.  I am more than willing to
receive and quite grateful for any and all assistance on this.  I think
I've got it right, but we'll have to wait and see what the AZh paper says.

And unless Tokovinin does say something specific in the text, he doesn't
mention it at all.

re the 67.7 day period... ...yes it does not fit too well to one of the
eclipses, but we have an upper constraint of 200 days and a lower
constraint of _possibly_ 20 days from the comments on the Galileo data,
although this does not necessarily preclude the 5.888 day period which
Sebastian prefers.


Meanwhile, I'm a bit intrigued by summat ;^) ... ...apparently the Galileo
single observation of a dip in delta Velorum's light output was mentioned
as part of a circular put out by South African amateurs, but obviously you
had not come across it... ...so despite this internet thingy, or possibly
because of the sheer profligacy of it [and the amount of stuff we therefore
need to wade through], things still fall through the cracks.

[NB, I've tried to make the above as clear as possible, but note I'm merely
an amateur, so sorry if I've made it more confusing than needs be].

Cheers

John

John Greaves
UK

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