[vsnet-chat 2560] NSV4189 Hydrae - A Large Amplitude Red Variable

["PETER F WILLIAMS" <PFWILLIAMS@onaustralia.com.au>]

Dear All,

Attention is directed to NSV4189 Hydrae as a large amplitude red variable
which appears to have been little studied in the past.  This star is
currently again at maximum brightness.

In 1994 Eugene Brings of Mendocino, California noted variability of NSV4189
during a program to photograph red stars from the NSV catalogue where
significant variation had been reported at infrared wavelengths.  A visual
study of this star by Peter Williams and Eugene Brings between 1994 and the
present has shown it to be an apparent Mira type variable of mean period
near 465 days.  However, a considerable range of +/- 60 days has been shown
over the comparatively few observed cycles for a star of clearly long
period.

A preliminary ephemeris for maximum brightness is JD2450180 + 465 days.

Average maximum magnitude from the 4 previously observed cycles is near
12.0 visual.  The present maximum of NSV4189 is near magnitude 11.0,
noteably brighter than that previously observed.  Unfortunately, no
reliable magnitudes are available for this field and we have therefore used
GSC magnitudes.  These appear to be somewhat in error (surprisingly) and
perhaps one magnitude fainter than expected.

A brief paper on our observations of this star is under preparation for the
Publications of the VSS RASNZ and will be submitted after conclusion of the
present observing season in June 2000.

Please enjoy the current bright maximum of NSV4189.

NSV Catalogue details of NSV4189 are:
08h 38m 04s -14d 38'.3 (1950)
Max 2.29 K
Min 3.47 K
Designation IRC-10202
Spectrum M8

Regards

Peter Williams, Heathcote, NSW
Eugene Brings, Mendocino, California

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