Chandra observations scheduled for RT Cru

[PTS]

AAVSO Special Notice #409
October 30, 2015

Chandra observations scheduled for RT Cru

Further to AAVSO Alert Notice 503
(https://www.aavso.org/aavso-alert-notice-503), Dr. Margarita
Karovska (Harvard-Smithsonian Center for Astrophysics) informs us
that the Chandra observations of the symbiotic variable RT Cru
have been scheduled.

Dr. Karovska writes: "In addition to the continuous, regular
monitoring [that observers have been providing since August 2014,
we] are requesting twice-weekly or more frequent [B, V, and visual
photometry and spectroscopy] throughout November 2015 in support of
Chandra observations scheduled for mid-November 2015.

"RT Cru is a fascinating member of a new class of hard X-ray
emitting symbiotic binaries. The RT Cru system contains a high-mass
white dwarf accreting from a mass-losing M giant. The white dwarf
is surrounded by an accretion disk fed by the wind of the red giant.

"The Chandra observations of RT Cru will help us understand the
characteristics of the accretion onto the white dwarf in this
sub-class of symbiotics. This is an important step for determining
the precursor conditions for formation of a fraction of asymmetric
Planetary Nebulae, and the potential of symbiotic systems as
progenitors of at least a fraction of Type Ia supernovae."

Please continue your B, V, and visual observations at least twice
weekly of RT Cru through December 5. Spectroscopy would be very
valuable and is strongly encouraged if at all possible. RT Cru
varies between 11.2 and 12.6 visual; as of 2015 October 18.77 UT
it was V=12.09(03) and B=13.48(03) (NLX, P. Nelson, Ellinbank, VIC,
Australia).

Coordinates: R.A. 12 34 53.74 Dec. -64 33 56.1 (2000.0)

Charts with a comparison star sequence for RT Cru may be created
using the AAVSO Variable Star Plotter (VSP, https://www.aavso.org/vsp).

Please submit observations promptly to the AAVSO International
Database using the name "RT CRU".

Observers who are able to obtain spectra should contact Elizabeth
Waagen (eowaagen@aavso.org) for instructions on how to submit their
data.


This AAVSO Special Notice was compiled by Elizabeth O. Waagen.

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