Central Bureau for Astronomical Telegrams
IAUC 5732: alpha PsA; SU Tau; 1993e
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Circular No. 5732
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
alpha PISCIS AUSTRINI
S. A. Stern, Southwest Research Institute, San Antonio; M. C.
Festou, Observatoire Midi-Pyrenees, Toulouse; and D. A. Weintraub,
Vanderbilt University, Nashville, report: "Mapping observations on
Feb. 20-21 revealed 1.3-mm continuum emission in a broad, disk-like
region around the nearby, main-sequence star alpha PsA (Fomalhaut, A3V;
distance 6.7 pc). The observations supporting this discovery were made
using the 7-channel MPIfR bolometer of the IRAM 30-m telescope on Pico
Vileta, with a halfpower bandwidth at 1.3 mm of 12". The emission
geometry appears to be a tilted disk with the position angle of the
major axis near 100 deg and an aspect ratio of 2:1; the major-axis
emission exceeds 20 mJy at the 450-500-AU contour (about 1' from the star).
Additional emission may be present at larger distances. The peak 1.3-mm
emission detected is 50 mJy, centered on the line of sight to the star.
The emission is ascribed to an assemblage of cold, orbiting dust grains
around the star. Although IRAS revealed that Fomalhaut is an infrared-
excess source, these observations constitute the first detection of this
extended, disk-like emission. Thus, after beta Pic (also A3V), this is
the second main-sequence star to have a detected disk, and the disk is
the first one around a main-sequence star to be mapped in thermal
emission. The fact that alpha PsA is 2.5 times closer to the earth
than beta Pic is makes it an ideal object for intensive study."
SU TAURI
This R-CrB variable is fading, as indicated by the following
visual magnitude estimates, communicated mainly by B. H. Granslo,
Fjellhamar, Norway: Mar. 20.51, 10.0 (M. Iida, Nagano, Japan); 23.42,
10.2 (M. Yamada, Ishikawa, Japan); 25.84, 10.4 (Granslo); 26.47,
10.5 (Yamada); 27.44, 10.8 (Yamada); 28.85, 11.3 (Granslo); 29.82,
11.6 (Granslo).
COMET SHOEMAKER-LEVY (1993e)
A. Cochran, University of Texas, reports that she obtained
spectra (range 300-570 nm) of this comet with the large cassegrain
spectrograph on the McDonald Observatory's 2.7-m telescope on Mar. 28.
The long slit was placed along the major axis of the object. A
preliminary look at the raw data shows no obvious emissions. The
comet was approximately uniformly bright over the inner 30". There was
an approximately uniform section of lower intensity to a total length of
1'. A weak condensation was visible near the western end.
1993 March 30 (5732) Brian G. Marsden
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