Central Bureau for Astronomical Telegrams
IAUC 8961: eta Car; C/2008 H6-H9
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Circular No. 8961
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)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)
eta CARINAE
J. C. Martin, University of Illinois at Springfield; K.
Davidson, University of Minnesota; and collaborators (R. M.
Humphreys and A. Mehner, University of Minnesota; F. Hamann,
University of Florida; G. Ferland, University of Kentucky; and K.
Ishibashi, Northwest Research Associates) report the first definite
sign of eta Car's next spectroscopic event that is predicted to
occur in 2009 January. Broad He II 468.6-nm emission has appeared
in blue and red Gemini/GMOS spectra obtained on 2008 July 4 and 17.
The central velocity is near -40 km/s heliocentric, the FWHM is
roughly 300 km/s, and the equivalent width is about 0.01 nm. In
eta Car (HD 93308), this very-high-excitation feature becomes
detectable only near a spectroscopic event, and it did not appear
in similar data obtained during 2007 June-July and 2008 February.
No existing model clearly predicts its appearance as early as six
months before the oncoming event (Martin 2006, Ap.J. 640, 474, and
references therein). The only other perceptible spectral changes
at this time involve the He I triplet (but not singlet) features.
P-Cyg absorption around -400 km/s in the He I 402.6-, 447.2-, and
471.3-nm emission lines has increased by about 50 percent since mid-
2007. Such absorption is expected to occur in outer regions of the
primary wind photoionized by the hot secondary star, if the latter
is now moving approximately between us and the primary. Thus it
helps to constrain the orbit orientation. For background
information see Ishibashi 2001, ASP Conf. Proc. 242, 53; Nielsen et
al. 2007, Ap.J. 660, 669; Humphreys et al. 2008, A.J. 135, 1249;
and Okazaki et al. 2008, http://lanl.arxiv.org/abs/0805.1794v1.
COMETS C/2008 H6-H9 (SOHO)
Further to IAUC 8957 and 8960, additional Kreutz sungrazers
have been found on SOHO website images. C/2008 H6 was very faint
(mag about 8) and diffuse. C/2008 H7 was very diffuse (mag about
7.5-8) with a faint tail. C/2008 H8 was extremely faint (mag about
8-8.5) and slightly diffuse. C/2008 H9 was tiny and stellar in
appearance (mag about 8).
Comet 2008 UT R.A.(2000)Decl. Inst. F MPEC
C/2008 H6 Apr. 27.188 2 25.7 +12 46 C2 EB 2008-L47
C/2008 H7 29.830 2 35.4 +13 31 C2 MM 2008-L47
C/2008 H8 30.881 2 39.1 +13 50 C2 MK 2008-L47
C/2008 H9 21.688 2 06.3 +11 05 C2 HS 2008-M10
(C) Copyright 2008 CBAT
2008 July 28 (8961) Daniel W. E. Green
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