Central Bureau for Astronomical Telegrams
IAUC 4922: AX Per; ARP 220
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Read IAUC 4923
Circular No. 4922
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 or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
AX PERSEI
M. F. Bode, R. J. Ivison, J. A. Roberts, Lancashire Polytechnic;
A. Evans, University of Keele; and J. Meaburn and S. Kemp,
University of Manchester, report: "Near-simultaneous optical/IUE
spectroscopy reveals dramatic changes in the spectrum of the
symbiotic star AX Per. High-dispersion (0.22 nm/mm at H-alpha) and
low-dispersion (7.9 nm/mm, 460-670 nm) spectroscopic observations
were performed with the Manchester Echelle Spectrograph on the
Isaac Newton Telescope, La Palma (low-dispersion mode is with a
grism). These show the He II 468.6-nm line to be undetected on
Sept. 16.2 (high dispersion) and Sept. 17.2 (low dispersion) UT.
The H-alpha line is characteristically double-peaked, with peak-to-
peak separation 85 +/- 3 km/s. The region around [O III] at 500.7
nm is dominated by the He I 501.7-nm line, which is also strongly
centrally-reversed. A high-dispersion IUE SWP spectrum was taken
on Sept. 16.7; the source was extremely weak, with few emission
lines present. He II at 164.0 nm is barely detectable, with flux
7 x 10E-13 erg sE-1 cmE-2. C IV at 155.0 nm is apparently absent.
Previous optical spectra, taken in 1988 Sept., showed strong He II
at 468.6 nm, as expected. H-alpha was of similar appearance to
that in recent observations. However, the He I 501.7-nm line lacked
central reversal, and Fe II at 501.8 nm was detected. The H-alpha/
H-beta ratio changed from 6.7 in 1988 Sept. to 3.4 a year later,
suggesting a significant increase in the optical depth in the
circumstellar nebula. From absolute calibration of the low-dispersion
spectra, it appears that AX Per brightened from V = 10.1 +/- 0.1 to
9.3 +/- 0.1 between the two epochs. Further simultaneous multi-
frequency spectroscopy is planned."
ARP 220
S. J. E. Radford, S. Guilloteau, and R. Lucas, Institut de
Radio Astronomie Millimetrique, Domaine Universitaire de Grenoble,
write: "On behalf of the IRAM staff, we report using the IRAM
millimeter interferometer to detect the HCN (1-0) line, 3.5-mm
continuum emission, and tentatively the HCO+ (1-0) line from the
starburst galaxy Arp 220. The HCN line has a peak amplitude of
0.1 Jy and a width greater than 500 km/s. The continuum flux is
0.025 Jy. The integrated intensity of the HCN line is constant
over projected baselines from 18 to 57 m, which implies that the
source is smaller than 4" or 5"."
1989 December 15 (4922) Daniel W. E. Green
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