NGC 7640 — Sc in Andromeda
Sc in Andromeda, 8.1 arcminutes across, its light 18 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 7640
What you are looking at
NGC 7640 is a late-type spiral: a small central bulge and open, loosely wound arms full of young stars and star-forming gas. We see it almost exactly edge-on, so its whole disc appears as one thin band of light, with dust showing as a dark line along its length. From edge to edge its visible disc spans about 42,000 light-years (taking its redshift distance, which for a galaxy this near is approximate), about half 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. It is cited in 181 scientific papers indexed by SIMBAD, and recorded there under 19 different catalogue designations.
When this light set out
The light that reaches us from NGC 7640 today set out about 18 million years ago, when grasslands were spreading across the continents. The galaxy is moving away from us at about 372 km/s (0.8 million mph), carried by the expansion of the universe. For a galaxy this close, its own motion through space is a large share of that speed, so the distance worked out from it is approximate; distances measured from individual stars in it can differ.
Finding it in the sky
NGC 7640 lies in Andromeda. It is best placed on autumn evenings: around 9:30 pm in October it stands about 89° high in the north, close to overhead, 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: UGC 12588 (0.7° away on the sky, at least 220,000 light-years from it); UGC 12632 (1.5° away on the sky, at least 470,000 light-years from it).
By apparent size it is number 30 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 71220 |
|---|---|
| Morphological type | Sc |
| Angular diameter | 8.09′ |
| Right ascension | 23h22m06.6s |
| Declination | +40°50′43.5″ |
| Constellation | Andromeda |
| Inclination | 85.7° |
| Light travel time | 18 million years |
| Bar | yes, from the catalogue |
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 8.1 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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