[vsnet-campaign-be 107] Delta Scorpii rising again

["Sebastian Otero" <varsao@fullzero.com.ar>]

Thom Gandet wrote:

>>Delta Sco, considering its spectral type, its past spectroscopic
behavior and its recent photometric behavior, may be a Herbig Be
star rather than a classical Be star.  The prior lack of convincing
evidence for a spectroscopic period ought to be re-examined, as the
recent photometry by Sebastian and others (IBVS 5026) does show
evidence for a period near 80-days.  However, it is difficult to
measure radial velocities of Be stars that are meaningful in terms
of Keplerian motion because of effects by gas streams, decretion/
accretion disk activity, etc.


Dear friends:
                   Tonight I observed delta Scorpii and Thom's words seem to
ring true.
The star is rising again and the activity is always in agreement with a 72 -
77 day period, slightly shorter than proposed by Thom.
                   I supposed the star was going to fade at last, but the
fading stopped near JD 2452015 that is exactly 3 cycles of 73 days later
than the first well-observed 2.15 minimum. The star has brightened by 0.05
magnitudes and it is very interesting to take a look at the following table
with maxima and minima. (JD's are approximated [little gaps in the data] but
they can't be off by more than 5 days)

FIRST CYCLE:

Maximum 1.91 -  JD 2451752
Minimum  2.15 -  JD 2451793

SECOND CYCLE:

Maximum 1.85 -  JD 2451824
Minimum  ??

THIRD CYCLE:  The star was not visible !!

FOURTH CYCLE:

Maximum  1.80 -  JD 2451978
Minimum   1.85 -  JD 2452015

Tonight's observation is 1.81 again, and this means that the star will
probably be VERY bright in a 20-25 days time. (maybe 1.7?).

I really don't know if there is a companion in a 75 day orbit inducing light
changes but the changes are there. Maybe with another cycle going on as
predicted, more can be said...

In 25 days we'll have another clue.


Best regards,
Sebastian Otero,
LIADA.




---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://vsnet.grisoft.com).
Version: 6.0.249 / Virus Database: 122 - Release Date: 13/04/01

VSNET Home Page

Return to Daisaku Nogami

---

vsnet-adm@kusastro.kyoto-u.ac.jp