J/A+A/602/A53 R Aqr SPHERE/ZIMPOL narrow-Hα image (Schmid+, 2017)
SPHERE/ZIMPOL observations of the symbiotic system R Aquarii.
I. Imaging of the stellar binary and the innermost jet clouds.
Schmid H.M., Bazzon A., Milli J., Roelfsema R., Engler N., Mouillet D.,
Lagadec E., Sissa E., Sauvage J.-F., Ginski C., Baruffolo A., Beuzit J.L.,
Boccaletti A., Bohn A.J., Claudi R., Costille A., Desidera S., Dohlen K.,
Dominik C., Feldt M., Fusco T., Gisler D., Girard J.H., Gratton R.,
Henning T., Hubin N., Joos F., Kasper M., Langlois M., Pavlov A., Pragt J.,
Puget P., Quanz S.P., Salasnich B., Siebenmorgen R., Stute M., Suarez M.,
Szulagyi J., Thalmann C., Turatto M., Udry S., Vigan A., Wildi F.
<Astron. Astrophys. 602, A53 (2017)>
=2017A&A...602A..53S 2017A&A...602A..53S (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, cataclysmic ; Photometry, H-alpha
Keywords: stars: individual: R Aqr - binaries: symbiotic -
stars: winds, outflows - circumstellar matter -
instrumentation: adaptive optics
Abstract:
R Aqr is a symbiotic binary system consisting of a mira variable, a
hot companion with a spectacular jet outflow, and an extended emission
line nebula. Because of its proximity to the Sun, this object has been
studied in much detail with many types of high resolution imaging and
interferometric techniques. We have used R Aqr as test target for the
visual camera subsystem ZIMPOL, which is part of the new extreme
adaptive optics (AO) instrument SPHERE at the Very Large Telescope
(VLT).
We describe SPHERE/ZIMPOL test observations of the R Aqr system taken
in Hα and other filters in order to demonstrate the exceptional
performance of this high resolution instrument. We compare our
observations with data from the Hubble Space Telescope (HST) and
illustrate the complementarity of the two instruments. We use our data
for a detailed characterization of the inner jet region of R Aqr.
We analyze the high resolution ~=25mas images from SPHERE/ZIMPOL and
determine from the Hα emission the position, size, geometric
structure, and line fluxes of the jet source and the clouds in the
innermost region <2"(<400AU) of R Aqr. The data are compared to
simultaneous HST line filter observations. The Hα fluxes and the
measured sizes of the clouds yield Hα emissivities for many
clouds from which one can derive the mean density, mass, recombination
time scale, and other cloud parameters.
Our Hα data resolve for the first time the R Aqr binary and we
measure for the jet source a relative position 45 mas West (position
angle -89.5°) of the mira. The central jet source is the strongest
Hα component with a flux of about 2.5x10-12erg/cm2/s. North
east and south west from the central source there are many clouds with
very diverse structures. Within 0.5" (100AU) we see in the SW a string
of bright clouds arranged in a zig-zag pattern and, further out, at
1"-2", fainter and more extended bubbles. In the N and NE we see a
bright, very elongated filamentary structure between 0.2"-0.7" and
faint perpendicular "wisps" further out. Some jet clouds are also
detected in the ZIMPOL [OI] and HeI filters, as well as in the
HST-WFC3 line filters for Hα, [OIII], [NII], and [OI]. We
determine jet cloud parameters and find a very well defined
correlation Ne∝r-1.3 between cloud density and distance to
the central binary. Densities are very high with typical values of
Ne~=3x105cm-3 for the "outer" clouds around 300AU,
Ne~=3x106cm-3 for the "inner" clouds around 50AU, and even
higher for the central jet source. The high Ne of the clouds implies
short recombination or variability timescales of a year or shorter.
Hα high resolution data provide a lot of diagnostic information
for the ionized jet gas in R Aqr. Future Hα observations will
provide the orientation of the orbital plane of the binary and allow
detailed hydrodynamical investigations of this jet outflow and its
interaction with the wind of the red giant companion.
Description:
The presented SPHERE/ZIMPOL images taken in the Hα filters
resolve the jet source and the mira variable in the R Aqr binary for
the first time unambiguously and with high astrometric precision. It
can be expected that successful re-observations of the stellar binary
are easy to achieve near photometric minimum allowing for a fast
progress in the determination of an accurate orbit in the future.
Objects:
-----------------------------------------
RA (2000) DE Designation(s)
-----------------------------------------
23 43 49.46 -15 17 04.1 R Aqr = HR 8992
-----------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
list.dat 140 1 Information of fits image
RAqrSZNHaFW0Oct2014.fits 2880 1242 fits image
--------------------------------------------------------------------------------
Byte-by-byte Description of file: list.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 12 F6.3 s RAs Right ascension (J2000)
14 A1 --- DE- Declination sign (J2000)
15- 16 I2 deg DEd Declination (J2000)
18- 19 I2 arcmin DEm Declination (J2000)
21- 26 F6.3 arcsec DEs Declination (J2000)
28- 33 F6.4 arcsec/pix Scale Scale of the image
35- 37 I3 --- Nx Number of pixels along X-axis
39- 41 I3 --- Ny Number of pixels along Y-axis
43- 46 I4 Kibyte size Size of FITS file
48- 75 A28 --- FileName Name of FITS file
77-140 A64 --- Title Title of the FITS file
--------------------------------------------------------------------------------
Acknowledgements:
Hans Martin Schmid, schmid(at)astro.phys.ethz.ch
(End) Patricia Vannier [CDS] 13-Jun-2017