NGC 4051 — SABb in Ursa Major
SABb in Ursa Major, 5.9 arcminutes across, its light 34 million years old. Measured by HyperLEDA, photographed by Pan-STARRS1. Recorded once.
About NGC 4051
NGC 4051 is a Seyfert galaxy, one with a bright active nucleus. Its central black hole is unusually variable, flickering in X-rays within hours, and has been weighed by watching how the light of gas around it responds.
What you are looking at
NGC 4051 is a spiral with a sizeable central bulge and well-defined arms, close in type to the Milky Way. A weak bar of stars crosses its centre. It is tilted about 49° 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 58,000 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 shines brightly with the light of gas falling into its central black hole. Three supernovae have been recorded in it, the first in 1983; the most recent include SN 1983I, SN 2003ie, SN 2010br. It is cited in 2,300 scientific papers indexed by SIMBAD, and recorded there under 75 different catalogue designations.
When this light set out
Its light has been travelling for about 34 million years. When it left, Antarctica had begun to freeze. The galaxy is moving away from us at about 704 km/s (1.6 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
NGC 4051 lies in Ursa Major. It is best placed on spring evenings: around 9:30 pm in April it stands about 85° 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: NGC 4013 (1.0° away on the sky, at least 600,000 light-years from it); NGC 4138 (1.4° away on the sky, at least 840,000 light-years from it); UGC 7089 (1.5° away on the sky, at least 870,000 light-years from it); NGC 4111 (1.6° away on the sky, at least 960,000 light-years from it), and 14 more.
By apparent size it is number 83 of the 12,657 galaxies on the Galaxy Origins register.
Measurements
| Catalogue | PGC 38068 |
|---|---|
| Morphological type | SABb |
| Angular diameter | 5.90′ |
| Right ascension | 12h03m09.7s |
| Declination | +44°31′52.4″ |
| Constellation | Ursa Major |
| Inclination | 48.7° |
| Light travel time | 34 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 5.9 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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