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Date and Time of the Query: 2019-06-15 T16:25:57 PDT
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For refcode 2005AJ....129.1873N:
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Copyright by American Astronomical Society. Reproduced by permission
2005AJ....129.1873N A Possible High Nova Rate for Two Local Group Dwarf Galaxies: M32 and NGC 205 James D. Neill and Michael M. Shara Abstract. We report the results of a preliminary nova survey of Local Group dwarf elliptical galaxies. We used the 15' field-of-view CCD camera on the 0.8 m telescope at the Tenagra Observatory to observe M32, NGC 205, NGC 147, and NGC 185 in their entirety every clear night over a 4.5 month interval and discovered one nova in M32 and a candidate nova in NGC 205. The nova in M32 was verified spectroscopically. The nova candidate in NGC 205 had an unusually low peak luminosity (M_V_=-5.1), and we were unable to obtain spectroscopic verification. Archival Hubble Space Telescope images provide us with a limit on the outburst amplitude for this object of >4.6 V magnitudes. These facts prompt us to consider the possibility that this object is not a genuine nova. We report a high bulk nova rate for M32 of 2^+2.4^_-1.0_ yr^-1^ and, assuming that the candidate nova is correctly identified, for NGC 205 of 2^+2.2^_-1.0_ yr^-1^. If the NGC 205 variable is not a nova, we calculate an upper limit on the bulk nova rate for NGC 205 of 1.5 yr^-1^. We report upper limits on the bulk nova rates in NGC 147 of 2 yr^-1^ and NGC 185 of 1.8 yr^-1^ and a combined bulk nova rate for the four galaxies of 4^+4.2^_-1.4_ yr^-1^ (2^+3.9^_-1.4_ yr^-1^ without the NGC 205 nova candidate). The bulk rates we report here are based on Monte Carlo simulations using nova maximum magnitudes and decline rates and individual epoch frame limits. From the Monte Carlo rates, integrated and extinction corrected V-band photometry, and (V-K)_0_ colors we derive a luminosity specific nova rate for M32 of 12.0^+14.4^_-6.0_ yr^-1^(10^10^L_sun,K_)^-1^ and for NGC 205 of 29.3^+32.3^_-14.7_ yr^-1^(10^10^L_sun,K_)^-1^ and for the combined four galaxies of 14.1^+14.8^_-4.9_ yr^-1^(10^10^L_sun,K_)^-1^ [7.0^+13.7^_-4.9_ yr^-1^(10^10^L_sun,K_)^-1^ without the NGC 205 nova candidate]. The higher combined rate is 2.5 {sigma} higher than expected from assuming a constant luminosity specific nova rate as a function of K-band luminosity as derived from more massive galaxies. If the higher rate is confirmed by surveys in subsequent seasons, it would imply either that dwarf elliptical galaxies have a higher interacting binary fraction than their higher mass counterparts, or that the completeness is higher for these less complex systems and the nova rates for larger, more distant systems are systematically underestimated. Keywords: Galaxies: Individual: M32, Galaxies: Individual: NGC 205, Galaxies: Individual: NGC 147, Galaxies: Individual: NGC 185, Stars: Novae, Cataclysmic Variables
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