Holmberg 15A

{{Short description|Elliptical galaxy in the constellation Cetus}}

{{Infobox galaxy

| name = Holmberg 15A

| discoverer = Erik Holmberg

| image = File:Holmberg 15A chandra.jpg

| caption = Holmberg 15A (in the center) in X-rays by Chandra X-ray Observatory

| epoch = J2000.0

| pronounce =

| constellation name = Cetus

| ra = {{RA|00|41|50.5}}

| dec = {{DEC|-09|18|11|}}

| z = 0.055672

| h_radial_v = {{val|16690|u=km/s}}

| gal_v = {{val|16747|u=km/s}}

| dist_ly = {{convert|704|e6ly|Mpc|abbr=on|lk=on}}
{{hub|0.678}}

| group_cluster = Abell 85

| type = cD;BrClG

| mass = 7{{e|13}}

| mass_light_ratio =

| size = {{convert|270000|ly|kpc|lk=on|abbr=on}}

| stars = 5{{e|12}}

| appmag_v = 14.7

| appmag_b =

| absmag_v =

| size_v = 1.3 moa

| notes =

| names = Abell 85-BCG, PGC 2501

| references =

}}

Holmberg 15A (abbreviated to Holm 15A) is a supergiant elliptical galaxy and the central dominant galaxy of the Abell 85 galaxy cluster in the constellation Cetus, about 700 million light-years from Earth.{{cite web| url = https://www.sciencealert.com/an-absolutely-gargantuan-black-hole-has-been-found-as-massive-as-40-billion-suns| title = Astronomers Just Found an Absolutely Gargantuan Black Hole The Mass of 40 Billion Suns| date = 6 August 2019}} It was discovered {{circa|1937}} by Erik Holmberg.{{cite journal

| doi = 10.1088/2041-8205/795/2/L31

| title = The Brightest Cluster Galaxy in Abell 85: The Largest Core Known So Far

| journal = The Astrophysical Journal

| volume = 795

| issue = 2

| pages = L31

| year = 2014

| last1 = López-Cruz | first1 = O.

| last2 = Añorve | first2 = C.

| last3 = Birkinshaw | first3 = M.

| last4 = Worrall | first4 = D. M.

| last5 = Ibarra-Medel | first5 = H. J.

| last6 = Barkhouse | first6 = W. A.

| last7 = Torres-Papaqui | first7 = J. P.

| last8 = Motta | first8 = V.

| arxiv = 1405.7758

| bibcode = 2014ApJ...795L..31L

| s2cid = 1140857

}} It became well known when it was reported to have the largest core ever observed in a galaxy, spanning some 15,000 light years, however this was subsequently refuted.Bonfini, Paolo; Dullo, Bililign T.; Graham, Alister W. (2015), [http://adsabs.harvard.edu/abs/2015ApJ...807..136B Too Big to Be Real? No Depleted Core in Holm 15A]Madrid, Juan P.; Donzelli, Carlos J. (2016), [http://adsabs.harvard.edu/abs/2016ApJ...819...50M The Abell 85 BCG: A Nucleated, Coreless Galaxy]