NSV 19448 - A
beta Lyrae-type eclipsing binary plus a surprise!
Lightcurve of NSV 19448. Period is 0.893025
However, discrepant points have been
subtracted to show this lightcurve. The star(s) displays 40 days long
brightenings every 357 days as seen in this lightcurve:
been used for this research.
Pojmanski, G., 2002, Acta
Astronomica, 52, 397, The All Sky Automated Survey (2002AcA....52..397P)
FOR NSV 19448
19448 facts as described in an alert sent to vsnet-alert and the AAVSO
|January 11, 2005
NSV 19448 = HD 109962 = GSC 8232 1689
at 12h 39m 07.89s -45º 33'
44.2" (2000.0) is brightening again.
A background mira on the line of sight of an EB-type eclipsing binary?
-HIGH RESOLUTION IMAGES NEEDED to solve the mira companion if it exists.
-VISUAL OBSERVATIONS AT HIGH POWER to resolve the 9.7-mag eclipser and
(currently) 10.5-mag mira if it exists.
-COLOUR PHOTOMETRY NEEDED to detect a reddening.
-IF IT IS A DOUBLE VARIABLE STAR, separation and PA measures of this new
visual binary (Francisco, someone in the South?)
I copy below info I sent last year when the star made another display.
It was classified as a MISC variable with a period of 360.475 d. in the
I have found it to be an eclipsing binary of the EB-type with elements:
I= HJD 2452491.552 + 0.893025 d. x E. Spectral type is F2V and the range
V= 9.54 - 9.84 (secondary minimum= 9.74) according to ASAS-3 data.
The lightcurve is here:
The object underwent four brightenings lasting ~40 days on April-May
March-May 2003, March-April 2004 and April-May,2005. There is a gap in
data so another "event" might have taken place on April-May 2002. During
star reaches V= 9.1-9.3.
On December 26, 2005, the star has started the current brightening,
by Patrick Wils in ASAS data.
Although 2MASS quick look images and POSS archival plates reveal no
candidate capable of being responsible for any coincidental line of
behaviour down to roughly within two arcseconds of HD 109962, I can't
thinking of a background mira possibility. The lightcurve seems to show
very regular pattern and maxima look like a mix between the EB
and a mira star maximum. Also the amplitude seems to be somewhat larger
unfiltered magnitudes (reported by Vello Tabur, Australia), so this
a clue of a reddening.
BUT it's not clear what it is. A mira that can get as bright as 10th
magnitude should stand out in 2MASS data.
Multiband photometry and especially spectroscopic analysis during
brightenings is essential to unveil the true nature of this object(s).
It would be interesting even visually to detect a companion or a color
change when this "thing" brightens!
I have made a chart for visual and photometry use (there is a nearby
with UBVRI) and it's available at:
Thanks John Greaves and Patrick Wils for their interest in this star.
Tabur from Australia has confirmed the outbursts on
unfiltered CCD images obtained with an ST6 + 100mm f/4.5 telephoto on
2001 May 9.510 and with a 140-mm f/2.8 telephoto lens on 2003 May
4.607 and on 2004 April 01.51.
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