Weak H-alpha emission from the recurrent nova T CrB
ATel #16214; V. Marchev, R. Zamanov (Bulgarian Academy of Sciences), D. Marchev (Shumen University)
on 28 Aug 2023; 19:02 UT
Credential Certification: R. K. Zamanov (rkz@astro.bas.bg)
Subjects: Optical, Cataclysmic Variable
T Coronae Borealis is a recurrent nova with recorded eruptions in 1866 and 1946, and a new outburst is expected in the next six months (Schaefer et al. 2023, ATel #16114, ; Maslennikova et al. 2023, Astronomy Letters).
On 27 August 2023 (from UT 19:20 till UT 20:20), we observed T CrB with the ESpeRo spectrograph at the 2.0 telescope of the Rozhen National Astronomical Observatory, Bulgaria (Bonev et al. 2017, Bulg. Astron. J., 26, 67). The spectrograph provides a high resolution of 0.05 A/px.
We measured equivalent width of the H-alpha emission line of only 3.2 +/- 0.5 A (angstroms) and distance between the peaks 2.4 A. For comparison, in Fig.1 are shown the H-alpha emission on 1 April 2021 (equivalent width 27 A), and on 29 July 2023 (equivalent width 5.8 A).
The observations suggest that the accretion disc around the white dwarf continue to decrease, and already is small. It will be interesting to see will the accretion disc disappear entirely in the next few months.
H-alpha emission line of T CrB.
