[vsnet-campaign-deltavel 24] Del Vel - 27.09 day period and other things

[Sebasti若n Otero <varsao@fullzero.com.ar>]

Dear friends:
                      Early this morning, if the period of delta Velorum is
27.09 days, the star should be in secondary eclipse.
                      My observations say no eclipse is occuring.

I've been carefully analysing Galileo data (thanks again to Paul Fieseler,
Galileo Mission, JPL, NASA) and the secondary eclipse lightcurve is almost
complete, which helps us establish the following elements for the secondary
eclipses:

Total duration: 0.89 days
Time spent at minimum: 0.176 days
Mideclipse epoch:  JD 2447851.690

Based on visual magnitudes for the other secondary eclipses and in a very
unlikely 27.09 day period,
we should have observed:

2451860.503       1.95
2451860.552       2.00
2451860.614       2.05
2451860.684       2.10
2451860.762       2.15
2451860.861       2.2
2451860.949       2.2
2451861.037       2.2
2451861.136       2.15
2451861.214       2.10
2451861.284       2.05
2451861.346       2.00
2451861.395       1.95

It didn't happen.

So the 45.150 day period is almost a certainty, and the secondary eclipse
will be on JD 2451870.04 (November 21st , 13hs. UT)

As you see, it looks like the secondary eclipse is longer than the primary.
That's why I asked people if this was possible. Everybody said yes. Juan
Fabregat from Spain explained that if primary eclipse occurs near
periastron, then the stars are travelling faster and the eclipse should be
shorter (the opposite goes for the secondary). He let me know the case of
V436 Persei, where the primary eclipse lasts 9 hours and the secondary 23.
Coincidentally, the amplitude and period are comparable to those of delta
Velorum: 0.36 mag. and 26 days.
Thanks also Fraser Farrell and all the people who answered my question.

I think delta Velorum sextuple star has been figured out.

Best wishes,
Sebastian.

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