NGC 3504 is a barred spiral galaxy in the constellation Leo Minor. It has a Hubble distance corresponding to 88 million light-years and was discovered by William Herschel in 1785. The luminosity class of NGC 3504 is I-II, with a broad HI line containing regions of ionized hydrogen. Additionally, it is classfied as a starburst galaxy. There is a large amount of molecular gas centered on the galactic nucleus. Compared with other barred spiral galaxies, NGC 3504 is in an early phase of its evolution.

Morphology

NGC 3504 is classified as a type (R1')SAB(rs)ab galaxy. It has a bright point-like nucleus embedded inside its galactic budge that is crossed by a thin bar. It has spiral arms found wrapping around its inner ring which then peels off to form an outer, broken pseudo-ring. The galaxy shows little evidence of star formation.

Star-forming disk

According to Hubble Space Telescope, a star-forming disk has been found around the nucleus of NGC 3504, which the size of the disk's axis is estimated to be 200 pc (~650 light years).

Mass

The mass of NGC 3504 has been difficult to narrow down, but it is believed to be between 2.5109 M⊙ and 9109 M⊙.

Supermassive black hole

The supermassive black hole in NGC 3504 is estimated to be 107.8 M○ (or 63 million solar masses), according to near-infrared K-band brightness measurements for the galaxy's budge.

Supernovae

Two supernovae have been observed in NGC 3504: SN 1998cf and SN 2001ac. SN 1998cf SN1998cf was discovered in March 1998 by Eric Emsellem via CCD images captured at Canada-France-Hawaii Observatory and also by Karl Gordon and Geoffrey Clayton from Louisiana State University. This supernova had an unknown type with a magnitude of 15. SN 2001ac SN 2001ac was discovered at magnitude 18.2, on 12 March 2001 by W. D. Li and S. Beckmann from the University of California, Berkeley. This supernova was initially thought to be type IIn, but later analysis concluded that it was a Calcium-rich supernova, sometimes referred to as a "gap" transient.

NGC 3504 group

NGC 3504 is the brightest member of the NGC 3504 Group, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster. There are eight other galaxies in the group including NGC 3380, NGC 3400, NGC 3414, NGC 3451, NGC 3512, UGC 5921 and UGC 5958. This NGC 3504 group is also mentioned by Abraham Mahtessian in his research paper published in 1998.