NGC 3504

NGC 3504 is a barred spiral galaxy in the constellation Leo Minor. It has a Hubble distance corresponding to 88 million light-years^[3] and was discovered by William Herschel in 1785.^[4]

NGC 3504
NGC 3504 (Hubble Space Telescope)
Observation data (J2000 epoch)
Constellation	Leo Minor
Right ascension	11h 03m 11.2s[1]
Declination	+27° 58′ 21″[1]
Redshift	1534 ± 2 km/s[1]
Apparent magnitude (V)	11.67[1]
Characteristics
Type	(R)SAB(s)ab[1]
Apparent size (V)	2.7′ × 2.1′[1]
Other designations
UGC 6118, MCG +05-26-039, PGC 33371[2]

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.^[5]

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.^[6]

Morphology

NGC 3504 is classified as a type (R₁')SAB(rs)ab galaxy.^[7][8] 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.^[9]

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).^[10]

Mass

The mass of NGC 3504 has been difficult to narrow down, but it is believed to be between 2.5*10⁹ M⊙ and 9*10⁹ M⊙.^[11]

Supermassive black hole

The supermassive black hole in NGC 3504 is estimated to be 10^7.8 M○ (or 63 million solar masses), according to near-infrared K-band brightness measurements for the galaxy's budge.^[12]

Supernovae

Two supernovae have been observed in NGC 3504:

• SN 1998cf (type unknown, mag. 15) 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.^[13][14]
• SN 2001ac (type gap, mag. 18.2) was discovered by LOTOSS (Lick Observatory and Tenagra Observatory Supernova Searches) on 12 March 2001.^[15] This supernova was initially thought to be type IIn or LBV,^[16] but later analysis concluded that it was a Calcium-rich supernova, sometimes referred to as a "gap" transient.^[17]

NGC 3504 group

NGC 3504 is the brightest member of the NGC 3504 Group (also known as LGG 227), 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.^[18] There are eight other galaxies in the group including NGC 3380, NGC 3400, NGC 3414, NGC 3451, NGC 3512, UGC 5921 and UGC 5958.^[19] This NGC 3504 group is also mentioned by Abraham Mahtessian in his research paper published in 1998.^[20]