New Activity Episode of the Unusual Variable Star DDE 175
ATel #14376; D. Denisenko (Vorobyovy Gory Education Center, Moscow, Russia; SAI MSU), D. Fernandez Ortiz, A. Kolesnikov, A. Minkovskiy, E. Tokareva (Vorobyovy Gory Education Center)
on 7 Feb 2021; 16:16 UT
Credential Certification: Denis Denisenko (d.v.denisenko@gmail.com)
Subjects: Optical, Request for Observations, Cataclysmic Variable, Nova, Variables
Referred to by ATel #: 14475
We report on the first observations of the unusual variable star DDE 175 = IPHAS J190356.18+090158.4 after the winter conjunction with the Sun. Observations were obtained remotely with the iTelescope.Net T11 instrument (0.50-m f/6.8 reflector + 0.66 focal reducer + FLI PL11002M CCD) located in Mayhill, New Mexico. The following magnitudes (unfiltered with the Red zero point) were obtained with T11 using 2MASS J19035259+0901228 as a reference star with r=14.66.
2020-04-19.4348 18.39
2020-05-31.4156 18.53
2020-06-21.3600 19.12
2021-02-07.5184 16.82
This is close to the maximum brightness level of this object as observed by Zwicky Transient Facility (Masci et al., 2019), see the Lasair light curve of ZTF18aaywchl. Before entering the solar conjunction DDE 175 was fading by 1.2 magnitude in one month, from 18.3r on 2020-10-01 to 19.7r on 2020-10-28, following the long plato lasting about 200 days from April to October 2020.
The most likely distance to DDE 175 according to Gaia EDR3 is 2.5 kpc, corresponding to distance modulus (m-M)=12.0. Assuming the galactic absorption in the direction of DDE 175 to be A_g=7.4, A_r=5.1, we obtain the absolute magnitude to be around M=-1 at the peak (r=15.9) and M~+4 at quiescence and nearly white colors. The classification of this variable star remain unclear.
The spectroscopy and simultaneous observations in the wide range of wavelengths are strongly needed to identify the nature of this unusual object.
Variable stars discovered by Denis Denisenko (DDE)
