ASTRO Arp 74

Arp 74/UGC 01626 is a pair of galaxies not far from Gamma Andromeda. Arp put it in his class for spirals with high surface brightness companions on their arm. Red shift puts it about 240 thousands of light-years away. There is no redshift data that I could find for its companion Arp 074B. A note at NED reads: "Companion 0.75, 169, 0.20 x 0.15, interaction. The arms appear to join close to the companion." This dates back to a 1973 paper. I don't see the interaction they mention. The fact the two arms happen to appear to meet near the position of the other galaxy seems immaterial as to decide if they are interacting or not. Arp 074B doesn't appear distorted. If interacting the smaller galaxy should show more distortion than the larger yet shows no sign of any distortion.

Arp 74 is classed by NED as SAB(rs)c. While the arms are obviously very different they don't earn it a peculiar designation. Unequal arms are rather common in fact. No interaction appears necessary either for the shape nor the high star formation rate they often have. Arp 074 is classed as IrS. Arp's comment on this one reads: "Broad, diffuse extension of arm leads to companion." Rather different from NED's note the arms appearing to join at the companion. Is Arp hinting that the arm leads to the other because they are related? I think he considered it a possibility that needed further investigation. That still hasn't happened it seems. Most likely Arp 74B is a distant background galaxy. The main galaxy appears to have little to no dust in its outer arms to dim a distant galaxy making it impossible to tell if it lies behind or not.

There is little on the rest of the field. There is a spiral at the bottom of my frame that seems as distorted as Arp 74 but didn't make his list. It is UGC 1615. It is classed as SB(s)dm: at NED. There's no distance estimate for it or any other galaxy in the field.

Arp's image
http://ned.ipac.caltech.edu/level5/A...big_arp74.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick

Rick,

that's a beautiful little spiral. Lots of knots in it's arms.

Stefan

"WA0CKY" schrieb im Newsbeitrag
...

Arp 74/UGC 01626 is a pair of galaxies not far from Gamma Andromeda.
Arp put it in his class for spirals with high surface brightness
companions on their arm. Red shift puts it about 240 thousands of
light-years away. There is no redshift data that I could find for its
companion Arp 074B. A note at NED reads: "Companion 0.75, 169, 0.20 x
0.15, interaction. The arms appear to join close to the companion."
This dates back to a 1973 paper. I don't see the interaction they
mention. The fact the two arms happen to appear to meet near the
position of the other galaxy seems immaterial as to decide if they are
interacting or not. Arp 074B doesn't appear distorted. If interacting
the smaller galaxy should show more distortion than the larger yet shows
no sign of any distortion.

Arp 74 is classed by NED as SAB(rs)c. While the arms are obviously very
different they don't earn it a peculiar designation. Unequal arms are
rather common in fact. No interaction appears necessary either for the
shape nor the high star formation rate they often have. Arp 074 is
classed as IrS. Arp's comment on this one reads: "Broad, diffuse
extension of arm leads to companion." Rather different from NED's note
the arms appearing to join at the companion. Is Arp hinting that the
arm leads to the other because they are related? I think he considered
it a possibility that needed further investigation. That still hasn't
happened it seems. Most likely Arp 74B is a distant background galaxy.
The main galaxy appears to have little to no dust in its outer arms to
dim a distant galaxy making it impossible to tell if it lies behind or
not.

There is little on the rest of the field. There is a spiral at the
bottom of my frame that seems as distorted as Arp 74 but didn't make his
list. It is UGC 1615. It is classed as SB(s)dm: at NED. There's no
distance estimate for it or any other galaxy in the field.

Arp's image
http://ned.ipac.caltech.edu/level5/A...big_arp74.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick


--
WA0CKY