[vsnet-chat 2367] Corwin on NGC 495 classification

[bas@mailhost.lowell.edu (Brian Skiff)]

     From Harold Corwin in re the classification of NGC 495.  Looks like
Hitoshi and I need some recalibration!

\Brian

=====================================

From: hgcjr@ipac.caltech.edu
Date: Fri, 22 Oct 1999 15:02:54 -0700
To: bas@lowell.edu
Subject: Re: NGC 495 type?

Hi, Brian,

>      There's been a bit of discussion on the Japanese variable-star list
> about the morphological type of NGC 495, which currently has a supernova.
> The RC3/NED type, (R')SB(s)0/a, is definitely too early, although the
> details apart from the stage are correct.  Wanna make a guess?

The RC3/NED type comes from my 1970 POSS1 collection
(Pub. Dept. Astron. Univ. Texas, Series II, Volume III,
Number 5).  There, I have an alternate type (SB(s)ab), 
also from POSS1, and the note "OXN [overexposed nucleus].  Red arms form (R')."
I also added "pec" to the morphology (copied into the
catalogues), probably because the arms splash out pretty 
broadly into a corona.

I just looked at the DSS images, both POSS1 and POSS2,
and see little reason to change the stage.  The arms 
are smooth in both images; I look for some choppiness
at Sa (e.g. the Sombrero).  The fact that the arms are 
enough brighter on the red POSS1 for me to comment on 
them 30 years ago, also suggests that the stage is early.  
An early stage also agrees with the measured colors (B-V 
= 1.05, U-B = 0.53 with a 53 arcsec aperture; these won't 
change much with extrapolation).  Finally, Nilson in UGC 
has "SB0/SBa" for the Hubble type.  This is about as 
close to an exact match with my estimate as we can expect 
-- though this, too, of course comes from POSS1.

I do see, however, why questions are coming up.  The arms 
are open enough to suggest an Sab or Sb.  But the galaxy 
is in a tight group in a cluster, and the arms are probably
influenced by the other nearby objects.

So, the word from here is still "(R')SB(s)0/a pec".   If 
threatened with a lifetime stuck on the Web, I might go as 
far as Sa, but certainly no further.

Best,
Harold

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