Supernova 1999an in Spiral Galaxy IC 755

The following is the data on Supernova 1999an:

Discovered: March 7th, 1999, by Beijing Astronomical Observatory

• Magnitude 15 at discovery
• Type II
• The Supernova as shown in the Kopernik image is about a magnitude dimmer.

From IAU Bulletin 7124 (3/11/99):

....... spectra obtained on Mar. 10.8, shows SN 1999an to be a type-II supernova with obvious P-Cyg Balmer lines. ....... {it has a} photospheric expansion velocity of 5300 km/s ....

Follow this Link to a NASA Web site on supernovas. It has a very nice animation and a description of what these objects are.

This is the data on Barred Spiral Galaxy IC 755 itself:

• Magnitude: 14.0
• RA: 12h 01m 10.2s
• Dec: +14°06'23" Epoch 2000
• Size (mins) 2.4' x 0.3'
• Constellation: Coma Berenices
• classification: SBb ?, Barred Spiral Galaxy, (uncertain)

Edge-on galaxy IC 755 is possibly a barred spiral. It has an asymmetric spindle shape with a bright drop-shaped nuclear region. Supernova 1999an is a type II, which most astronomers consider to result from the explosion of a single, very massive, and relatively young star. These types of stars are only found in the arms of spiral galaxies.

Dreyer's description from the Index Catalog(IC): Most extremely faint, small, extended, between 2 stars.

Based on the published red shift, a rough distance estimate for IC 755 and supernova 1998an is: 80,000,000 light years, with the galaxy being 67,000 light years in diameter.

Click below to

George Normandin, KAS

April 18th, 1999