Central Bureau for Astronomical Telegrams
IAUC 6423: 1996ai; CM Dra
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Circular No. 6423
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
SUPERNOVA 1996ai IN NGC 5005
A. V. Filippenko, University of California (UC) at Berkeley,
reports: "Preliminary inspection of an uncalibrated, somewhat noisy
CCD spectrum (range 360-760 nm), obtained by N. P. Vogt (UC, Santa
Cruz) and M. A. Bershady (Pennsylvania State University) on June 20
UT with the Lick Observatory 3-m Shane reflector, suggests that SN
1996ai (IAUC 6422) is a supernova, probably of type Ia prior to
maximum brightness. There is a broad absorption trough at 614 nm,
the defining feature of type-Ia supernovae, but this might instead
be redshifted H-alpha absorption in a type-II object (although the
corresponding H-alpha emission line is weak or absent). No other
deep features are visible; weak ones are consistent with the type-
Ia classification. The object appears to be quite red, perhaps due
to extinction; a relatively strong (EW = 0.3 +/- 0.1 nm), narrow Na
D absorption line at the redshift of the host galaxy is visible.
Crude CCD magnitude estimates from H. Teplitz (UC, Los Angeles) on
June 20 with the Lick 1-m Nickel telescope: B = 16.5, V = 15.0, R =
14.5, I = 13.5."
CM DRACONIS
E. Guinan, G. McCook, and S. Wright, Villanova University,
write: "We have made a possible photometric detection of a
planetary transit eclipse for the eclipsing-binary star CM Dra ---
selected as a planet-search target because its orbital plane is
seen almost exactly edge-on (Doyle et al. 1995, BAAS 27, 1382).
Photoelectric photometry of CM Dra has been conducted from Mt.
Hopkins since 1995 using the Four College Consortium 0.8-m APT.
The binary (P = 1.268 days) has been well behaved, showing the
expected mutual eclipses of the two stellar components and nearly
constant light between the narrow eclipse phases. During a 3.5-hr
observation beginning June 1.177 UT, CM Dra was fainter by 0.08 mag
in the I band; if we assume that this I decrease is due to a planet
transiting one of the two dM5 stars, it would have a diameter of
about 0.85 that of Jupiter. From the lower limit to the transit
duration, the possible planet would have an orbital period of at
least several months. Though this decrease in light may be due to
starspot development, photometry the day before and after the
dimming event showed the system to be at its usual brightness.
Evidence of the existence of a planet around CM Dra is being
investigated by searching for small periodic deviations of the
eclipse timings; a planet of Jupiter's mass at 1 AU would produce
about 17-s periodic shift (observable with accurate photometry) in
the arrival times of the eclipses of the stars."
(C) Copyright 1996 CBAT
1996 June 20 (6423) Daniel W. E. Green
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