NGC 5907 has long been considered a prototypical example of a warped spiral in relative isolation. In 1998, a faint ring structure, likely caused by a disrupteddwarf spheroidal galaxy, was first observed around the galaxy.[6] This challenged the assumption of isolation and suggests the gravitational perturbations induced by the stream progenitor may be the cause for the warp. Then, in 2008, an international team of astronomers announced the presence of an extended double loop tidal stream coiling around the galaxy.[7] The existence of part of these tidal streams has been recently challenged by some deeper surveys, which show only a single knee-shaped stream as opposed to the full double loop structure.[8] This shorter stream has a length of 45′ in the sky (or a physical size of 220 kpc) and has a surface brightness ranging from 27.6 mag/arcsec2 at its brightest to 28.8 at its faintest.[9]
Anultraluminous X-ray source,NGC 5907 ULX-1, is located in the galaxy.[10] This source is also called an ultraluminous X-ray pulsar (ULXP) because it exhibits a rapid pulsation effect. This pulsation has a period of 5.7 days and is caused by a rotatingneutron star orbiting ahigh mass companion.[11] The neutron star itself has a spin period of 1.13 seconds and seems to be accelerating; its period ten years prior was 1.43 seconds.[10] It is one of the brightest such source yet discovered with a luminosity over 1041 erg/s (7 orders of magnitude more luminous than the Sun).[12] Notably, its peak luminosity is over 1000 times greater than theEddington luminosity for a neutron star.[10]
NGC 5907 and the galaxyKUG 1513+566 are listed together asHolm 704 inErik Holmberg'sA Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems, published in 1937.[13]
NGC 5907 is part of a group of galaxies that bears its name. The NGC 5907 group (also known asLGG 396) has at least four members, includingMessier 102,NGC 5879, and UGC 9776.[14]
NGC 5907 is also known as NGC 5906.[4][18] This second NGC number refers to a fainter part of the galaxy[4] lying west of the dust lane[18] that was recorded by astronomer and physicistGeorge Johnstone Stoney on April 13, 1850.[4]
^Liu, M. C.; Marleau, F. R.; Graham, J. R.; Charlot, S.; Sackett, P.; Zepf, S. E. (December 1998). "Weighing the Stellar Content of NGC 5907's Dark Matter Halo".Bulletin of the American Astronomical Society.30: 1258.Bibcode:1998AAS...193.0807L.
^Holmberg, Erik (1937). "A Study of Double and Multiple Galaxies Together with Inquiries into some General Metagalactic Problems".Annals of the Observatory of Lund.6: 1.Bibcode:1937AnLun...6....1H.
^Garcia, A. M. (1993). "General study of group membership. II. Determination of nearby groups".Astronomy and Astrophysics Supplement Series.100: 47.Bibcode:1993A&AS..100...47G.
