Central Bureau for Astronomical Telegrams
IAUC 7465: C/2000 O1; HD 155826
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Circular No. 7465
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, 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)
URL http://cfa-www.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)
COMET C/2000 O1 (KOEHN)
MPEC 2000-O22 shows the identification, by B. G. Marsden, of
this comet with the LINEAR "asteroidal" objects 1998 XA_70 and 1999
UJ_10, together with improved orbital elements: T = 2000 Jan. 27.35
TT, Peri. = 55.11 deg, Node = 88.86 deg, i = 148.10 deg (equinox
2000.0), q = 5.9219 AU, e = 1.0009.
HD 155826
C. Lisse and A. Schultz, Space Telescope Science Institute; Y.
Fernandez, University of Hawaii; S. Peschke, European Space Agency;
M. Ressler, Jet Propulsion Laboratory, NASA; D. Backman, Ames
Research Center, NASA; and C. Kaminski and B. Golisch, Infrared
Telescope Facility (IRTF), NASA, report the discovery of an
extremely red object located 7" northwest (p.a. 323 deg) of the
bright binary system HD 155826: "The infrared cameras NSFCAM and
MIRLIN were used at the IRTF on the nights of June 18 and 19 to
image the area around HD 155826. Originally reported by IRAS as
one source detected at 12-100 microns, within the error ellipse of
HD 155826, two bright point sources were found in MIRLIN's
broadband N field at 0.63 and 1.3 Jy. HD 155826 is easily detected
in our NSFCAM z, J, H, and K' images, but there is no apparent
counterpart for the new source down to mag 14 in Gunn z, J, or the
Aladin sky catalogue. The new source may have been detected,
however, at low S/N by NSFCAM in H and K' at mag 14 and 13,
respectively. The detection of the second, non-optical, source
explains the confusing K-(IRAS 12 microns) colors originally
assigned to HD 155826 as a possible Vega-like system (Aumann 1985,
PASP 97, 885; Walker and Wolstencroft 1988, PASP 100, 1509;
Sylvester et al. 1996, MNRAS 279, 915). Assuming that the new
object and HD 155826 are associated, the 1".3 FWHM point-spread-
function diameter at 10 microns implies that any unresolved source
at the distance of HD 155826, 31 pc, should be 33 AU or less in
size. A fit to the IRAS long-wavelength fluxes yields a color
temperature of about 130 K and a lower size limit for an optically
thick source with 1.3 Jy at 10 microns of about 2 AU. The field is
within 12 deg of the Galactic center and < 7' from the Galactic
plane, so the possibility of a chance alignment of two unconnected
systems cannot yet be ruled out. Barring that, we conclude that
the most likely identity of the 'companion' is either a protostar
or carbon star with a thick shell (it is too small and hot to be
cirrus, too big to be a planet, and too faint at J and K to be a
brown dwarf)."
(C) Copyright 2000 CBAT
2000 July 25 (7465) Daniel W. E. Green
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