The environment of M85 optical transient 2006-1: Constraints on the progenitor age and mass

E. O. Ofek, S. R. Kulkarni, A. Rau, S. B. Cenko, E. W. Peng, J. P. Blakeslee, P. Côté, L. Ferrarese, A. Jordán, S. Mei, T. Puzia, L. D. Bradley, D. Magee, R. Bouwens

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42 Scopus citations


M85 Optical Transient 2006-1 (M85 OT 2006-1) is the most luminous member of the small family of V838 Mon-like objects, whose nature is still a mystery. This event took place in the Virgo Cluster of galaxies and peaked at an absolute magnitude of MI ≈ -13. Here we present Hubble Space Telescope images of M85 OT 2006-1 and its environment, taken before and after the eruption, along with a spectrum of the host galaxy at the transient location. We find that the progenitor of M85 OT 2006-1 was not associated with any star-forming region. The g- and z-band absolute magnitudes of the progenitor were fainter than about -4 and -6 mag, respectively. Therefore, we can set a lower limit of ∼50 Myr on the age of the youngest stars at the location of the progenitor that corresponds to a mass of <7 M. Previously published line indices suggest that M85 has a mean stellar age of 1.6 ± 0.3 Gyr. If this mean age is representative of the progenitor of M85 OT 2006-1, then we can further constrain its mass to be less than 2 M . We compare the energetics and mass limit derived for the M85 OT 2006-1 progenitor with those expected from a simple model of violent stellar mergers. Combined with further modeling, these new clues may ultimately reveal the true nature of these puzzling events.

Original languageEnglish
Pages (from-to)447-450
Number of pages4
JournalAstrophysical Journal
Issue number1
StatePublished - 10 Feb 2008
Externally publishedYes


  • Stars: individual (M85 OT 2006-1, V838 Mon, M31 RV, V4332 Sgr)


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