Archival Images of the Nebula Associated with ASASSN-V J205457.73+515731.9
ATel #13829; D. Denisenko (SAI MSU)
on 23 Jun 2020; 14:24 UT
Credential Certification: Denis Denisenko (d.v.denisenko@gmail.com)
Subjects: Optical, Cataclysmic Variable
H. E. Bond (ATel #13825) has reported the detection of the faint nebula associated with the novalike variable ASASSN-V J205457.73+515731.9 (T. Jayasinghe et al., ATel #13824). The star is actually located close to the western edge of the nebula, in the most dense part of it (bow shock) as seen on the color-combined DSS finder chart uploaded to http://scan.sai.msu.ru/~denis/J205457+515731-BRIR.jpg (10'x10' FOV, North up, East left). Since the Red POSS-II plate was used as a green channel in RGB composite image, the nebula appears to be green.
The variable and nebula are located in Cygnus, at the galactic latitude of +4.4 deg. Four sets of images of this field in Halpha, r and i filters were obtained with the 2.5-meter Isaac Newton Telescope in the course of IPHAS project (Barentsen et al., 2014). The observations were made on 2003 Nov. 08, 2005 Nov. 19, 2006 Oct. 02 and 2013 Aug. 09. Color composite images using i filter as R channel, Halpha filter as G channel and r filter as B channel are showing the structure of the nebula in more detail, as compared to DSS plates. The combined IPHAS image is uploaded to http://scan.sai.msu.ru/~denis/J205457+515731-IPHAS.jpg (5'x5' FOV, North up, East left, scale 0.33"/pixel).
By the remarkable coincidence, the bright 12.7m star TYC 3587-837-1 (20 55 06.87 +51 58 53.8) close to the northern edge of nebula, 84.5" East and 81.9" North of ASASSN-V J205457.73+515731.9, has the parallax similar to that of new variable (1.845+/-0.026 vs 1.742+/-0.021 ps). Moreover, it's proper motion (1.84+/-0.05, 10.53+/-0.04 mas/yr) is pointed away from the central part of the nebula described by Bond. ASASSN-V J205457.73+515731.9 is currently moving at (-10.99+/-0.04, -2.88+/-0.04) mas/yr. Tracing the motions back, sky positions of the two stars were coinciding to within 1 arc sec 6450+/-150 years ago (4450+/-150 BC). Future kinematic and spectroscopic analysis of ASASSN-V J205457.73+515731.9 and TYC 3587-837-1 is required to verify their common origin and possible connection to the past eruption having created the nebula.
This work has made use of Archives of the Isaac Newton Group of telescopes available online from Astronomical Data Centre at Cambridge Astronomical Survey Unit website http://casu.ast.cam.ac.uk/casuadc/
