(cba:news) MM Hya rises from its long sleep

Joe Patterson jop at astro.columbia.edu
Sun Mar 8 12:08:00 EST 1998


Dear CBAers,                                         March 8, 1998.

     Last night Jonathan found MM Hya="Hya 1" (in Downes and Shara
catalogue) at V=13.8.  The star has an orbital period of 82.9 min, and
is thus one of our favorite li'l short-period guys.  However, no light
curves have been obtained in outburst, ever.  So we are pow'f'l
motivated to cover the present outburst with long, tree-to-tree
coverage.

     The outburst period is definitely long, possibly as long as 20
years - last known one occurred about when Jonathan was learning to
finger-paint.  And it's definitely a superoutburst.  His light curve
last night showed a classic superhump of 0.25 mag amplitude.  The best
fit period was 86+-3 min, but the observation was short and needs
refinement over a much longer baseline.  A quite nice paper on this
star (and others) is by Misselt and Shafter 1995 (AJ 109, 1757).

     The Tololo run is over now, so we cast this out to the CBA world.
The star is located at 2000 coords 9 14 14.0, -6 47 45.  There's a
chart at our website, also listed as PG 0911-066, its other name.
We've been following it sporadically throughout the year to build
baseline for an accurate Porb measurement.  But this is outburst, quite
a different matter.

     I dunno how long it will stay bright.  But however long it stays,
keep after it a bit longer to watch for echo outbursts.

     This is a definite winner.  And equatorial too.  Polish up that
telescope and let 'er rip!  Pay no attention to that rogue Moon which
may be lurking nearby.  The usual practice, unfiltered time-series
photometry with respect to one of the two comparison stars on the
chart, is fine.  And if you measure the delta-mag between those two
comparison stars, so much the better.

     Lemme know what you can get - I'll analyze the data as soon as it
comes in and advise on the status of our period-finding.

     Quick update on other campaigns:
T Pyx.  Over.  Enemy vanquished.
HP Lib.  Just getting started.  Good morning target for all locations.
AM CVn.  Also near start.  Good for pretty much all northerners.
DI UMa.  Gotta keep pushing it for another month.  Working very well,
         but the star's frequent up and down excursions make it more
         difficult to splice together light curves at a similar
         luminosity state.  We'll make it if the DI entrepeneurs keep
         the faith.  You know who you are out there.
RZ LMi.  Basically the same story.
DW UMa.  Hold your fire.  Too much other stuff in that part of the sky
         this year.
AH Men.  Getting wonderful data sets from Marc Bos.  As long as he
         keeps doing it, all you other Southerners are off the hook!
         But he could use some help.

Website at http://cbastro.org


        joe




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