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Optical observations of KT Eri = Nova Eridani 2009

ATel #2327; E. Ragan, T. Brozek, K. Suchomska, A. Skalbania, P. Konorski, C. Galan, E. Swierczynski, T. Tomov, M. Mikolajewski (Uniwersytet Mikolaja Kopernika, Torun, Poland), P. Wychudzki (UMK, Olsztyn Planetarium and Astronomical Observatory)
on 3 Dec 2009; 21:16 UT
Credential Certification: Toma Tomov (tomtom@astri.uni.torun.pl)

Subjects: Optical, Binary, Nova, Star

Referred to by ATel #: 2331, 2392

We report on optical observations of Nova Eri 2009 obtained at the Nicolaus Copernicus University Observatory (Torun, Poland) and the Olsztyn Planetarium and Astronomical Observatory.

Using a 60 cm Cassegrain telescope (Torun) and a 25 cm Schmidt-Cassegrain telescope (Olsztyn) we estimated the V brightness of the Nova to ~8.30+/-0.04 mag and ~8.59+/-0.01 mag on Nov. 27.00 UT and Nov. 27.91 UT. USNO-B1.0 0798-0048756 and TYC 5325-1102-1 were used as comparison stars. Basing on the "Pi of the Sky" consortium photometry (vsnet-alert 11695, 11696) and the AAVSO data we estimated that the maximum V~5.6 mag occurred around Nov. 15.0 UT which gives approximately 8 and 15 days for the t2 and t3 times. Making use of five different Maximum Magnitude Rate of Decline calibrations we derived an average absolute V magnitude to around -8.7.

Spectral observations were performed in the range 4400-7000 AA using an echelle spectrograph (R~11000) attached to the 60/90 cm Schmidt-Cassegrain telescope (Torun) on Nov. 26.33 UT and Nov. 27.75 UT. The spectrum is dominated by very wide emission lines typical for a He/N nova. For the complex emission profiles of Halpha and Hbeta we measured FWHM ~3000 km/s and ~2600 km/s respectively and six emission peaks at velocities approximately -1800 km/s, -1000 km/s, -450 km/s, 225 km/s, 1600 km/s and 1900 km/s. A wide and weak P Cyg absorption is visible at about -3000 km/s in Hbeta profile. The equivalent width of the interstellar NaI D1 line and the relation of Munari & Zwitter (1997) give an E(B-V)~0.08. Hence, we can derive an approximate distance to the Nova Eri 2009 to around 6.5 kpc.

The high galactic latitude (about -32 degr) location of the star can explain the small value estimated for E(B-V). A distance of 6.5 kpc means that the 15 mag star observed at approximately the same coordinates before the outburst is too bright to be a progenitor of Nova Eri 2009.