NGC 7721 — Sc in Aquarius
Sc in Aquarius, 3.1 arcminutes across, its light 97 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 7721
What you are looking at
NGC 7721 is a late-type spiral: a small central bulge and open, loosely wound arms full of young stars and star-forming gas. Its disc is turned almost exactly side-on to us: the galaxy appears as a narrow blade of light, and its dust as a dark seam running along it. From edge to edge its visible disc spans about 88,000 light-years, close to the width of the Milky Way.
What astronomers have recorded
SIMBAD, the reference database astronomers use, classes it as a member of a group of galaxies. One supernova has been recorded in it: SN 2007le. It is cited in 159 scientific papers indexed by SIMBAD, and recorded there under 13 different catalogue designations.
When this light set out
Its light has been travelling for about 97 million years. When it left, dinosaurs were at their peak. The galaxy is moving away from us at about 2,015 km/s (4.5 million mph), carried by the expansion of the universe.
Finding it in the sky
In the sky, NGC 7721 sits within the constellation Aquarius. It is best placed on autumn evenings: around 9:30 pm in October it stands about 43° high in the south, seen from the middle of the United States.
Its neighbours
At almost the same distance from us, and so its neighbours in space as well as on the sky: IC 5334 (2.2° away on the sky, at least 3,770,000 light-years from it).
By apparent size it is number 469 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 72001 |
|---|---|
| Morphological type | Sc |
| Angular diameter | 3.13′ |
| Right ascension | 23h38m48.5s |
| Declination | -06°31′04.8″ |
| Constellation | Aquarius |
| Inclination | 81.4° |
| Light travel time | 97 million years |
| Bar | not recorded |
Check every figure above in the NASA/IPAC Extragalactic Database
What is sold
A print of this galaxy and the record of the calculation, once. When it sells it leaves the register and is not offered again. We assign no names and no ownership — nobody can sell you those.
At 3.1 arcminutes this is a Exceptional galaxy, which is the tier where a real photograph shows clear structure and dust lanes. The tier comes from the measured diameter, not from a price list.
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