NGC 3729 is a barred spiral galaxy (type SB(r)a pec) situated in the northern constellation of Ursa Major. It lies at a distance of approximately 65 million light‑years (20 Mpc) from the Milky Way, which, given its apparent dimensions of 2.8′ × 1.8′, corresponds to a physical size of roughly 60 000 light‑years across.
The galaxy was discovered by the astronomer William Herschel on 12 April 1789. Its central region features a bright nucleus embedded within a bar measuring about 0.5 × 0.1 arcminutes; at the ends of the bar an inner ring containing several bright knots is visible. The outer envelope appears asymmetric and faint, with condensations that may represent disturbed satellite material.
NGC 3729 is a member of the M 109 Group, itself part of the southern Ursa Major sub‑clusters within the Virgo Supercluster. It forms a close pair with the nearby galaxy NGC 3718, located 11.5 arcminutes to the west; tidal interactions between the two are considered a plausible explanation for the observed morphological disturbances.
Observations in the far‑ultraviolet and H‑α bands reveal active star formation within the inner ring. Dynamical studies suggest the presence of an intermediate‑mass black hole at the galaxy’s centre, with mass estimates ranging from 4 × 10⁴ M☉ to 4 × 10⁵ M☉ based on bulge luminosity in the Kₛ band.
No classical supernovae have been recorded in NGC 3729, but a luminous red nova designated AT 2018hso (apparent magnitude 19.4) was detected on 31 October 2018.
Key data
- Right ascension: 11 h 33 m 49.3 s (J2000)
- Declination: +53° 07′ 32″ (J2000)
- Redshift: 1 060 ± 1 km s⁻¹
- Apparent visual magnitude (V): 11.0
- Other catalog identifiers: UGC 6547, CGCG 268‑051, MCG +09‑19‑117, PGC 35711
References
- Wikipedia, “NGC 3729,” retrieved from the article on NGC 3729.
- NASA/IPAC Extragalactic Database (NED) entry for NGC 3729.
- Herschel’s original discovery records (1789).