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the picture is far more complex than the below two mails could suggest. Furthermore, some published work is wrongly cited/interpreted. 1. we never claim (A&A Lett 389, L51) there was an F-type star in V838 Mon prior to its explosion, only that its combined optical-IR colors resembled those of a F0 star *IF* the extinction is E(B-V)=0.5 and *IF* the extinction law is the one valid for the diffuse interstellar medium (the one characterized by R_V = 3.1). The distance to the star plays no role here. The F0 colors pertained to the combined light of the components of the binary system. 2. the distance of 790 pc has been direved under the assumption of a flat scattering disk seen pole-on and cetered on the star. Other assumptions (flat slab of interstellar material, sferically symmetric circumstellar material centered on the star) have lead to different published distances, 1.8, 3.5, >6 kpc. Coming announced astro-ph entries should deal with even more complex scattering dust geometries. 3. polarimetry suggests a distance not exceeding a few kpc. 4. there is a B3V star still sthere, and its spectrophotometric parallax is 10.5 kpc (IAUC 8005) if the calibration for nearby B3V stars holds for B3V stars at the edge of the galactic thin disk, where the metallicity is -0.5 dex lower than in the solar neighborhood. And if the B3V star in V838 Mon is a genuine B3V star and if the reddening is is E(B-V)=0.5 and if the extinction follow the stardard R_V = 3.1 law. Ulisse Munari, Padova and Asiago Observatories On Tue, 23 Sep 2003, Alon Retter wrote: > Dear Sebastian, > > The conclusion that the progenitor was an F-type star by Munari et al. > (2002) was based on a distance of 790+/-30 pc. However later detailed > works (Bond et al. 2003; Tylenda 2003, Crause et al. 2003) showed that the > light echo can only give a lower limit on the distance, which is 5-8 Kpc. > Crause's work uses the latest images and thus their lower limit of D > 8 > Kpc is the best value. A factor of 10 in the distance makes a huge > difference. > > Regards, > Alon > > On Mon, 22 Sep 2003, Sebastian Otero wrote: > > > http://vsnet.usyd.edu.au/news/newsevents/articles/2003/sep/16_star.shtml > > > > About V838 Mon. > > My question is: wasn't the progenitor an F-type star?? It seems it was a red > > giant. > > Someon ecould clarify? > > > > Thanks! > > Sebastian.
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