NGC 3631 — Sc in Ursa Major
Sc in Ursa Major, 3.7 arcminutes across, its light 56 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 3631
What you are looking at
NGC 3631 is a late-type spiral: a small central bulge and open, loosely wound arms full of young stars and star-forming gas. It is tilted about 35° to our line of sight, enough to show both the shape of its arms and the depth of its disc. From edge to edge its visible disc spans about 60,000 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
Halton Arp included it in his 1966 Atlas of Peculiar Galaxies as Arp 27, a list of galaxies with unusual, disturbed shapes. Boris Vorontsov-Velyaminov listed it as VV 363 in his catalogue of interacting galaxies. Two supernovae have been recorded in it, the first in 1965; the most recent include SN 1965L, SN 2016bau. It is cited in 387 scientific papers indexed by SIMBAD, and recorded there under 33 different catalogue designations.
When this light set out
The light that reaches us from NGC 3631 today set out about 56 million years ago, when the planet had come through its hottest interval since the dinosaurs. The galaxy is moving away from us at about 1,163 km/s (2.6 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
In the sky, NGC 3631 sits within the constellation Ursa Major. From most of the United States it never sets: it circles the north celestial pole all year, and stands highest on spring evenings, around April.
Its neighbours
At almost the same distance from us, and so its neighbours in space as well as on the sky: NGC 3718 (1.7° away on the sky, at least 1,690,000 light-years from it); NGC 3729 (1.9° away on the sky, at least 1,870,000 light-years from it); NGC 3756 (2.6° away on the sky, at least 2,520,000 light-years from it); NGC 3733 (2.7° away on the sky, at least 2,580,000 light-years from it).
By apparent size it is number 289 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 34767 |
|---|---|
| Morphological type | Sc |
| Angular diameter | 3.71′ |
| Right ascension | 11h21m02.9s |
| Declination | +53°10′10.4″ |
| Constellation | Ursa Major |
| Inclination | 34.7° |
| Light travel time | 56 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 3.7 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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