749 research outputs found
The spectroscopic orbit and the geometry of R Aqr
R Aqr is one of the closest symbiotic binaries and the only D-type system
with radial velocity data suitable for orbital parameters estimation. The aims
of our study are to derive a reliable spectroscopic orbit of the Mira
component, and to establish connections between the orbital motion and other
phenomena shown by R Aqr. We reanalize velocity data recently published by
McIntosh & Rustan complemented by additional velocities. We find an eccentric
orbit (e=0.25) with a period 43.6 yr. This solution is in agreement with a
resolved VLA observation of this system. We demonstrate that the last 1974-1981
increase of extinction towards the Mira occured during its superior
spectroscopic conjunction, and can be due to obscuration by a neutral material
in the accreting stream. We also show that jet ejection is not connected with
the orbital position.Comment: 7 pages, 4 figures, accepted for publication in A&
Symbiotic stars: Observations confront theory
In this paper, I present and discuss some recent observational results which
may have important implications for our understanding of late phases of binary
evolution.Comment: 8 pages, 3 figures; to appear in the proceedings of the Asiago
Workshop on Symbiotic Stars, A. Siviero and U. Munari eds., Baltic Astronomy
special issu
On the uniqueness of -gonal automorphisms of Riemann surfaces
Let be a compact Riemann surface of genus . A cyclic subgroup of
prime order of is called properly -gonal if it has a fixed
point and the quotient surface has genus . We show that if , then a
properly -gonal subgroup of is unique. We also discuss some
related results.Comment: final version, 9 pages, minor improvements, added 2 reference
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