NGC 3718 — Sa in Ursa Major
Sa in Ursa Major, 4.7 arcminutes across, its light 48 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 3718
NGC 3718 is a strongly warped galaxy: a broad dust lane twists across its centre, the disc bent by the gravity of neighbours. It belongs to a small group that includes the compact group Hickson 56.
What you are looking at
NGC 3718 is an early-type spiral: a large, bright central bulge wrapped in smooth, tightly wound arms. Its disc is steeply tilted, about 67° from face-on, so it appears as a long oval. From edge to edge its visible disc spans about 65,000 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 Seyfert galaxy: its nucleus is lit by gas falling into its central black hole, though dust hides part of that glow from us. Halton Arp included it in his 1966 Atlas of Peculiar Galaxies as Arp 214, a list of galaxies with unusual, disturbed shapes. Boris Vorontsov-Velyaminov listed it as VV 1449 in his catalogue of interacting galaxies. It is cited in 411 scientific papers indexed by SIMBAD, and recorded there under 38 different catalogue designations.
When this light set out
The light that reaches us from NGC 3718 today set out about 48 million years ago, when the planet had come through its hottest interval since the dinosaurs. The galaxy is moving away from us at about 993 km/s (2.2 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 3718 lies in 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 3729 (0.2° away on the sky, at least 160,000 light-years from it); UGC 6446 (1.1° away on the sky, at least 920,000 light-years from it); NGC 3756 (1.4° away on the sky, at least 1,140,000 light-years from it); NGC 3631 (1.7° away on the sky, at least 1,440,000 light-years from it), and 4 more.
By apparent size it is number 146 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 35616 |
|---|---|
| Morphological type | Sa |
| Angular diameter | 4.70′ |
| Right ascension | 11h32m34.8s |
| Declination | +53°04′04.4″ |
| Constellation | Ursa Major |
| Inclination | 67.3° |
| Light travel time | 48 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 4.7 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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