arXiv subjects

Linda Schmidtobreick

Publications and source records attributed to Linda Schmidtobreick.

21 records · Page 2Linked to original sources

arXiv2008

V2051 Oph after superoutburst: out-of-plane material and the superhump light source

We performed a detailed spectroscopic analysis of the dwarf nova V2051 Oph at the end of its 1999 superoutburst. We studied and interpreted the simultaneous behaviour of various emission lines. We obtained high-resolution echelle spectroscopic data at ESO's NTT with EMMI, covering the spectral range of 4000--7500 Angstrom. The analysis was performed using standard IRAF tools. The indirect imaging technique of Doppler tomography was applied, in order to map the accretion disc and distinguish between the different emission sources. The spectra are characterised by strong Balmer emission, together with lines of HeI and the iron triplet FeII 42. All lines are double-peaked, but the blue-to-red peak strength and central absorption depth vary. The primary's velocity was found to be 84.9 km/sec. The spectrograms of the emission lines reveal the prograde rotation of a disc-like emitting region and, for the Balmer and HeI lines, an enhancement of the red-wing during eclipse indicates a bright spot origin. The modulation of the double-peak separation shows a highly asymmetric disc with non-uniform emissivity. This is confirmed by the Doppler maps, which apart from the disc and bright spot emission also indicate an additional region of enhanced emission in the 4th quadrant (+Vx, -Vy), which we associate with the superhump light source. Given the behaviour of the iron triplet and its distinct differences from the rest of the lines, we attribute its existence to an extended gas region above the disc. Its origin can be explained through the fluorescence mechanism.

astro-ph↗

arXiv2008

SS433: Observation of the circumbinary disc and extraction of the system mass

The so-called "stationary" H-alpha line of SS433 is shown to consist of three components. A broad component is identified as emitted in that wind from the accretion disc which grows in speed with elevation above the plane of the disc. There are two narrow components, one permanently redshifted and the other permanently to the blue. These are remarkably steady in wavelength and must be emitted from a circumbinary ring, orbiting the centre of mass of the system rather than orbiting either the compact object or its companion: perhaps the inner rim of an excretion disc. The orbiting speed (approximately 200 km/s) of this ring material strongly favours a large mass for the enclosed system (around 40 solar masses), a large mass ratio for SS433, a mass for the compact object plus accretion disc of ~16 solar masses and hence the identity of the compact object as a rather massive stellar black hole.

astro-ph↗

arXiv2007

Fluctuations and symmetry in the speed and direction of the jets of SS433 on different timescales

ABRIDGED We present new results on the variations in speed and direction of the jet bolides in the Galactic microquasar SS433, from high resolution spectra, taken with the ESO 3.6-m New Technology Telescope almost nightly over 0.4 of a precession cycle. We find: (i) These data exhibit multiple ejections within most 24-hour periods and, throughout the duration of the observing campaign, the weighted means of the individual bolides, in both the red jet and the blue jet, clearly exhibit the pronounced nodding known in this system. (ii) We present further evidence for a 13-day periodicity in the jet speed, and show this cannot be dominated by Doppler shifts from orbital motion. (iii) We show the phase of this peak jet speed has shifted by a quarter of a cycle in the last quarter-century. (iv) We show that the two jets ejected by SS433 are highly symmetric on timescales measured thus far. (v) We demonstrate that the anti-correlation between variations in direction and in speed is not an artifact of an assumption of symmetry. (vi) We show that a recently proposed mechanism (Begelman et al 2006) for varying the ejection speed and anti-correlating it with polar angle variations is ruled out. (vii) The speed of expansion of the plasma bolides in the jets is approximately 0.0024c. These novel data carry a clear signature of speed variations. They have a simple and natural interpretation in terms of both angular and speed fluctuations which are identical on average in the two jets. They complement archival optical data and recent radio imaging.

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