The Superantennae
RA: 19h 25m 28.9sec Size: 45" (nucleus) , 5 arc minutes with tail extensions
DEC: -72° 45' 31" m = +16.7
No, no, you can’t ever seen this one from Houston (except on the web) but it is an interesting extraordinary object that I thought will fill in the unusual category.
One of the most remarkable sources of galaxy-galaxy collisions is the powerful source of infrared emission from IRAS 19254-7245 (a double galaxy) discovered by the Infrared Astronomy Satellite. This object is located in the southern constellation of Pavo. It exhibits the same slender tails of the classical Antennae, (a/k/a ring tail galaxies) NGC 4038/4039 in the northern constellation Corvus.
Recall that NGC 4038/4039 exhibit tidal tails roughly 150 kpc in total length based upon a redshift distance of 18.5 Mpc (Redshift 1,391 km/sec, Hubble constant = 75 km/sec/Mpc). At a distance of 250 Mpc, (from its 18,680 km/sec redshift) the apparent length of the tidal tails of IRAS 19254-7245 is greater than 350 kpc, at least 3 times larger than the extent of those exhibited by NGC 4038/4039 thus it has been nicknamed the “SUPERANTENNAE”. See the photo comparison below.
Radial velocity data along the two galaxy nuclei indicate that the Superantennae system consists of two disk galaxies: a bright edge on component 3 times more massive than our Milky Way, and a dimmer companion seen nearly face on. A study of this object by Igor Mirabel and his two co-workers found that the merging of this galaxy pair occurred 1 billion years ago. This conclusion was based upon an observed 200 km/sec velocity of material to reach the tip of the southern tail. These now tenuous tails will eventually escape into intergalactic space. This compared to NGC 4038/4039 which are just now colliding and undergoing rapid/massive star formation.
NGC 4038/4039 on the left. IRAS 19254-7245, the “SuperAntennae”on the right, both to scale according to actual size. The bar just to the left of the Superantennae corresponds to 1 arc minute.
The large energy motion from galaxy interacting models suggests that rapid star formation took place for about 20 million years at the predicted high rate of 150 M¤ /yr. Such a high starburst rate implies a predicted supernova rate of 4 supernovae/yr. The investigators have suggested that deep broad band CCD cameras could search for such supernovae in this galaxy pair as well as other superluminous galaxies.
Further investigations by Luis Colina and his two co-workers (Space Science Telescope Institute) indicate a “quasar type” central nucleus obscured by huge amounts of gas/dust clouds to explain the shape of the spectral line profiles.
Being located in the southern constellation Pavo, the Superantennae not visible from the United States.
REFERENCES
Colina, L., Lipari, S., Macchetto, F., 1991, Massive Star Formation and Superwinds in IRAS 19224-7245 (The "Super Antennae"), Astrophysical Journal, 379, p. 113-121.