S. Nakano, Sumoto, Japan, reports the discovery by Yukio Sakurai, Otsuka-cho, Mito, Ibaragi-ken, of a possible "slow" nova, on Fuji G400 film taken with a 300-mm f/2.8 lens, located at R.A. = 17h52m33s.5, Decl. = -17o40'52" (equinox 2000.0); the photograph taken on Feb. 20.806 UT shows the star as red in color and of mag 11.4. Patrol films taken by Sakurai during 1993-1994 show no candidate at this location, but the star is visible on films beginning in 1995 January (when it was of mag 12.5) and continuing through May, August-October, and again in 1996 January-February -- the star slowly brightening over the past year. M. Hazen, Harvard- Smithsonian Center for Astrophysics, reports that a search of some 200 plates in the Harvard plate collection, rather evenly distributed in date of exposure during 1930-1951 and reaching blue mag 14 (for earlier plates) to 16 (later plates), shows no obvious variable star at this location. R. H. McNaught, Anglo-Australian Observatory, reports that a search of Schmidt films reveals "no strong indication of a red variable that can reach mag 12, but there are three red excess objects within about 1' of the quoted position. One is clearly variable but in the range R = 17-20 and is about 1' west of Sakurai's position. Neither of the other red stars is obviously variable and are of (very roughly) R = 16 and 18." He notes that a more precise position would be useful. S. Benetti and H. W. Duerbeck, European Southern Observatory, report: "E. Cappellaro (Osservatorio Astronomico di Padova) observed this possible nova with the Dutch 0.9-m telescope at La Silla (ESO) on Feb. 23.3 UT, finding indeed a new star; preliminary photometry gives V = 12.8, B-V = +0.6, V-R = +0.6, V-I = +1.0. An inspection of a fully-reduced CCD spectrogram (range 375-985 nm; resolution 1.6 nm), taken by B. Leibundgut (ESO) with the ESO 3.6-m reflector (+ EFOSC1) on Feb. 23.4, reveals that the spectrum is consistent with a reddened early G-type star of high luminosity; no emission lines are visible. H-beta is in absorption at 485.7 nm, while H-alpha could be present in absorption, blended with another absorption feature (at 657.75 nm). Na I D lines are the strongest absorption feature of the spectrum (measured at 588.7 nm). The probable pre-outburst counterpart is visible as a star of mJ = 21, mR = 20.5 on the ESO/SRC sky survey films. While the outburst amplitude and lightcurve suggest a slow or symbiotic nova, the lack of obvious emission lines one year after brightening is very unusual."
International Astronomical Union Circular
- Pub Date:
- February 1996