130 research outputs found
The peculiar ejecta of the nova V1425 Aquilae
Many important details of the mechanisms underlying the ejection of material
during a (classical) nova eruption are still not understood. Here we present
optical spectroscopy and narrow-band images of the nova V1425 Aql, 23 years
after the nova eruption. We find that the ejecta consist of two significantly
different components. The first resembles what is commonly seen in novae, that
is, a symmetric distribution centred on the position of the underlying
cataclysmic binary and presenting both allowed (hydrogen and helium) and
forbidden ([OIII] and [NII]) transitions. The second one, on the other hand,
consists of material travelling at an approximately three times higher velocity
that is not visible in the allowed transitions, presents a significantly
different [NII] - [OIII] ratio, and is located at approximately 2.3 arcsec to
the southwest of the position of the binary. Comparing the velocities and
spatial extensions of the two ejecta, we find that both originated in the same
nova eruption. We explore possible extrinsic and intrinsic mechanisms for the
asymmetry of the high-velocity material in the form of asymmetrically
distributed interstellar material and magnetic accretion, respectively, but
find the available data to be inconclusive. From the expansion parallax, we
derive a distance for the nova of 3.3(3) kpc.Comment: 13 pages, 9 figures. Version updated for language editin
Life after eruption - I. Spectroscopic observations of ten nova candidates
We have started a project to investigate the connection of post-novae with
the population of cataclysmic variables. Our first steps in this concern
improving the sample of known post-novae and their properties. Here we present
the recovery and/or confirmation of the old novae MT Cen, V812 Cen, V655 CrA,
IL Nor, V2109 Oph, V909 Sgr, V2572 Sgr, and V728 Sco. Principal photometric and
spectroscopic properties of these systems are discussed. We find that V909 Sgr
is a probable magnetic CV, and that V728 Sco is a high-inclination system. We
furthermore suggest that the two candidate novae V734 Sco and V1310 Sgr have
been misclassified and instead are Mira variables.Comment: 11 pages, 7 figures (some of them in lower resolution), to be
published in MNRA
The emission distribution of RR Pictoris
We present time-resolved optical spectroscopy of the old nova RR Pic. Two
emission lines (Halpha and He I) are present in the observed part of the
spectrum and both show strong variability. Halpha has been used for Doppler
tomography in order to map the emission distribution in this system for the
first time. The resulting map shows the emission from the disc as well as two
additional emission sources on the leading and trailing side of the disc.
Furthermore we find evidence for the presence of either a disc-overflow or an
asymmetric outflow from the binary with velocities up to +- 1200km/s. The
origin of the outflow would be the emission source on the leading side of the
accretion disc.Comment: Latex, 7 pages, 10 figure
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