Irregular Galaxy NGC 55 (2009 August 12)

[bystander]

http://apod.nasa.gov/apod/ap090812.html

(Barred irregular galaxy) NGC 55 and the spiral galaxy NGC 300 have traditionally been identified as members of the Sculptor Group, a nearby group of galaxies in the constellation of the same name. However, recent distance measurements indicate that the two galaxies actually lie in the foreground. It is likely that NGC 55 and NGC 300 form a gravitationally bound pair.

These recent measurements were in 2003. What's the verdict, are they foreground or part of the Sculptor Group?

APOD: 2002 August 21 - Spiral Galaxy NGC 300
APOD: 2002 August 22 - Shell Game in NGC 300
APOD: 2005 August 20 - The Stars of NGC 300

[neufer]

• There's a hold up in the Bronx,
  Brooklyn's broken out in fights.
  There's a traffic jam in Harlem
  That's backed up to Jackson Heights.
  There's a scout troup short a child,
  Kruschev's due at Idlewild
  NGC 55, Where Are You?

http://apod.nasa.gov/apod/ap090812.html

(Barred irregular galaxy) NGC 55 and the spiral galaxy NGC 300 have traditionally been identified as members of the Sculptor Group, a nearby group of galaxies in the constellation of the same name. However, recent distance measurements indicate that the two galaxies actually lie in the foreground. It is likely that NGC 55 and NGC 300 form a gravitationally bound pair.

These recent measurements were in 2003. What's the verdict, are they foreground or part of the Sculptor Group?

APOD: 2002 August 21 - Spiral Galaxy NGC 300
APOD: 2002 August 22 - Shell Game in NGC 300
APOD: 2005 August 20 - The Stars of NGC 300

I vote No. Throw da bums out!

The Sculptor Group should be redefined to be the gravitationally-bound core around the Sculptor Galaxy (NGC 253)

<<The Sculptor Group is a loose group of galaxies near the south galactic pole. The group is one of the closest groups of galaxies to the Local Group; the distance to the center of the group from the Milky Way is approximately 3.9 Mpc.

The Sculptor Galaxy (NGC 253) and a few other galaxies form a gravitationally-bound core in the center of this group. A few other galaxies at the periphery may be associated with the group but may not be gravitationally bound. Because most of the galaxies in this group are actually weakly graviationally bound, the group may also be described as a filament.>>

[bystander]

• ...
  Kruschev's due at Idlewild
  NGC 55, Where Are You?

Where's Idlewild? Who's Kruschev? And shouldn't that be 54?

[neufer]

• ...
  Kruschev's due at Idlewild
  NGC 55, Where Are You?

Where's Idlewild? Who's Kruschev? And shouldn't that be 54?

[apodman]

Where's Idlewild? Who's Kruschev? And shouldn't that be 54?

What is a yute?

Near JFK, a cousin of Khrushchev, Yes, and (excuse me, your honor) two YOUTHS.

[apodman]

Near JFK

You mean like the same place?

Yup.

a cousin of Khrushchev

I mean like the same guy?
Yup again.

---

When I think of irregular galaxies, I think formless. To me, this one looks more like a malformed or partly formed spiral. But from the edge it could be an illusion.

---

Apodman was born in Hackensack Hospital (a major respected medical center), so no asparagus is being cast here no matter how it might sound. I'm just reporting the facts. In late 1963 and 1964 there was a rush to rename everything after JFK. Idlewild Airport became JFK. Cape Canaveral became Cape Kennedy before it went back to being Cape Canaveral (adjacent to the Kennedy Space Center). Jacqueline Kennedy sued Hackensack's neighboring town of South Hackensack, NJ (home of the fictional South Hackensack Institute of Technology, sister school of Texas' fictional Sam Houston Institute of Technology) to keep them from changing the town's name to Jacqueline Township. Thank you, Jackie, for helping to preserve New Jersey's share of the joke.

[neufer]

What do irregular galaxies have to do with "South Hackensack Institute of Technology"

[apodman]

What do irregular galaxies have to do with "South Hackensack Institute of Technology"?

Their symmetry is for scat.

[Jay]

Is the NGC 55 image posted to APOD today, a composite made up of a variety of spectral elements and reconstituted to the various colors shown? Or is the image a literal view in the visible light spectrum?

Thanks for illuminating me.

[Chris Peterson]

Is the NGC 55 image posted to APOD today, a composite made up of a variety of spectral elements and reconstituted to the various colors shown? Or is the image a literal view in the visible light spectrum?

The data were collected as separate luminance, red, green, and blue images which were combined to produce the final color image. With that set of filters, the image can be considered fairly representative of "true color", meaning what you'd see with your eyes if they were more sensitive to dim light.

[neufer]

<<Some galaxies do not have a regular shape, like a spiral or an elliptical galaxy. Those galaxies are known as irregular galaxies. Their shape is uncommon. They do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure. Collectively they are thought to make up about a quarter of all galaxies. Most irregular galaxies were once spiral or elliptical galaxies but were deformed by gravitational action. Irregular galaxies also contain abundant amounts of gas and dust.

There are two major Hubble types of irregular galaxies:

* An Irr-I galaxy (Irr I) is an irregular galaxy that features some structure but not enough to place it cleanly into the Hubble sequence. de Vaucouleurs subtypes this into galaxies that have some spiral structure Sm, and those that do not Im.

* An Irr-II galaxy (Irr II) is an irregular galaxy that does not appear to feature any structure that can place it into the Hubble sequence.

A third classification of irregular galaxies are the dwarf irregulars, labelled as dI or dIrrs. This type of galaxy is now thought to be important to understand the overall evolution of galaxies, as they tend to have a low level of metallicity and relatively high levels of gas, and are thought to be similar to the earliest galaxies that populated the Universe. They may represent a local (and therefore more recent) version of the faint blue galaxies known to exist in deep field galaxy surveys.

Some of the irregular galaxies are small spiral galaxies that are being distorted by the gravity of a larger neighbor.

The Magellanic Cloud galaxies were once classified as irregular galaxies, but have since been found to contain barred spiral structures, and have been since re-classified as "SBm", a fourth type of barred spiral galaxy, the barred Magellanic spiral type.>>

--------------------------------------------------------------

<<The original Baker Street irregulars were a group of fictional characters featured in the Sherlock Holmes stories. They were a group of street urchins who helped Holmes out from time to time. The head of the group was called Wiggins. Holmes paid them a shilling a day (plus expenses), with a guinea prize (worth one pound and one shilling) for a vital clue. They first appeared in Conan Doyle's original Sherlock Holmes story, A Study In Scarlet (1886).

The modern organization

The Baker Street Irregulars is also the name of an organization of Sherlock Holmes enthusiasts founded in 1934 by Christopher Morley. Members have included John Stevens Berry, Rex Stout, Banesh Hoffmann, U.S. presidents Franklin Delano Roosevelt and Harry S Truman, actors Douglas Wilmer and Curtis Armstrong and the science fiction and fantasy writers Poul Anderson, Fletcher Pratt, Isaac Asimov and Neil Gaiman. They continue to convene every January in New York City for an annual dinner, which forms part of a weekend of celebration and study involving other Sherlockian groups and individuals as well.>>