[Paper Review] Detailed optical studies of the galactic supersoft X-ray source QR And (RXJ0019.8+2156)

B. Deufel, H. Barwig+3 more|arXiv (Cornell University)|Nov 18, 1998

Astrophysical Phenomena and Observations1 references4 citations

TL;DR

This study presents extensive optical observations of the galactic supersoft X-ray source QR And (RXJ0019.8+2156), combining long-term photometry (1992–1996) and high-resolution spectroscopy (1997). It identifies quasi-periodic variations with a period of ~1.8 hours, detects blue- and red-shifted HeII and Balmer line satellites indicating high-velocity outflows, and applies Doppler tomography to reveal emission from low-velocity regions within the binary system, not an accretion disk.

ABSTRACT

We present high-speed long term photometric observations from 1992 to 1996 (UBVRI), as well as recently obtained (1997) spectrophotometric and high resolution spectroscopic studies of the bright galactic supersoft X-ray source RXJ0019.8+2156. Our photometry reveals a highly variable object. The shortest observed quasi-periodic variations are humps with a period of approx 1.8h. The timings of the main minimum are not exactly regular and occur on average around phase phi=0.0. With our new data set we calculated an update of the orbital period. Our simultaneous spectroscopic and spectrophotometric studies from 1997 give an even more detailed insight: blue and red shifted satellite lines at HeII 4686 and at the strong Balmer lines, which are interpreted as high velocity outflows, can clearly be detected. We also present for the first time an analysis of this supersoft source by means of Doppler tomography. The lines of HeII (4542,4686), H_a and H_b show no emission from an accretion disk. These emission lines originate in regions within the binary system with very low velocities. The spatial origin of the emitting material is not quite clear and will be investigated in a follow-up paper.

Motivation & Objective

• To investigate the optical variability and spectral characteristics of the supersoft X-ray source QR And (RXJ0019.8+2156) over multiple years.
• To determine the orbital period and timing of minima using long-term photometric data from 1992 to 1996.
• To analyze high-resolution spectroscopy and spectrophotometry from 1997 to identify emission line kinematics and outflow structures.
• To apply Doppler tomography to map the spatial distribution of emitting regions in the binary system.
• To determine whether emission lines originate in an accretion disk or in other low-velocity regions within the system.

Proposed method

• Long-term photometric monitoring in UBVRI bands from 1992 to 1996 to track brightness variations and identify periodic behavior.
• Simultaneous spectrophotometric and high-resolution spectroscopic observations in 1997 to study line profiles and velocity shifts.
• Doppler tomography applied to HeII (4542, 4686) and Balmer lines (Hα, Hβ) to reconstruct the spatial distribution of emitting material.
• Analysis of blue- and red-shifted satellite lines in HeII 4686 and Balmer lines to infer high-velocity outflows.
• Comparison of observed line profiles with disk emission models to rule out accretion disk origin for the emission lines.
• Orbital period update based on refined timing of minima from photometric light curves.

Experimental results

Research questions

• RQ1 What are the timescales and characteristics of the optical variability in QR And, particularly regarding quasi-periodic oscillations?
• RQ2 What causes the blue- and red-shifted satellite lines observed in HeII and Balmer lines, and what do they reveal about outflows?
• RQ3 Where within the binary system is the emission from HeII and Balmer lines originating, and is it consistent with an accretion disk?
• RQ4 How does the spatial distribution of emitting material in QR And compare to standard disk emission models?
• RQ5 What is the updated orbital period of QR And based on the full photometric dataset?

Key findings

• The source exhibits quasi-periodic brightness variations with a dominant period of approximately 1.8 hours, indicating a strong modulation in the system.
• The main minima occur at phase φ ≈ 0.0, though the timings are not strictly regular, suggesting complex variability.
• Blue- and red-shifted satellite lines in HeII 4686 and the Balmer lines are clearly detected, indicating high-velocity outflows from the system.
• Doppler tomography reveals that emission lines in HeII (4542, 4686) and Hα, Hβ originate in regions with very low velocities, not in a standard accretion disk.
• The spatial origin of the emitting material remains ambiguous, with no clear evidence for disk emission, and is proposed to be in a different, yet-to-be-identified region of the binary system.
• The study provides the first application of Doppler tomography to a galactic supersoft X-ray source, offering new insights into the kinematics of its emission regions.