UGC 9128

{{Short description|Galaxy in the constellation Boötes}}

{{Infobox Galaxy

| name = UGC 9128

| image = UGC 9128.jpg

| caption = UGC 9128 imaged by the Hubble Space Telescope

| epoch = J2000

| ra = {{RA|14|15|56.70}}{{cite journal|bibcode=1999ApJS..125..409C|doi=10.1086/313286|title=Arcsecond Positions of UGC Galaxies|year=1999|last1=Cotton|first1=W. D.|last2=Condon|first2=J. J.|last3=Arbizzani|first3=E.|journal=The Astrophysical Journal Supplement Series|volume=125|issue=2|pages=409–412|s2cid=122517686 |doi-access=free}}

| dec = {{DEC|23|03|16.2}}

| dist_ly = 6.8–7.8 Mly (2.1–2.4 Mpc)

| mass = {{val|1.3|0.2|e=7}} {{cite web |title=Dynamics of starbursting dwarf galaxies |url=https://www.aanda.org/articles/aa/pdf/2014/06/aa22657-13.pdf |access-date=8 August 2021}}

| size = 3300 ly

| type = dIrr{{Cite journal|last=McConnachie|first=Alan W.|date=2012-06-05|bibcode=2012AJ....144....4M|journal=The Astronomical Journal|language=en|volume=144|issue=1|pages=4|doi=10.1088/0004-6256/144/1/4|issn=0004-6256|arxiv=1204.1562|title=The Observed Properties of Dwarf Galaxies in and Around the Local Group|s2cid=118515618 }}

| constellation name = Boötes

| names = UGC 9128, DDO 187,{{cite journal|doi=10.1086/301157 |title=DDO 187: Do Dwarf Galaxies Have Extended, Old Halos? |date=2000 |last1=Aparicio |first1=Antonio |last2=Tikhonov |first2=Nikolay |last3=Karachentsev |first3=Igor |journal=The Astronomical Journal |volume=119 |issue=1 |pages=177–187 |arxiv=astro-ph/9909493 |bibcode=2000AJ....119..177A }} PGC 50961

}}

UGC 9128 is a dwarf irregular galaxy around 6.8–7.8 Mly (2.1–2.4 Mpc) away; it is thought to be in the Local Group, although its membership is not certain.{{cite web |title=Dwarf galaxy: small but perfectly formed |url=https://esahubble.org/images/potw1117a/ |website=www.spacetelescope.org |access-date=8 August 2021 |language=en}} The galaxy has a mass of about {{val|1.3|0.2|e=7|u={{solar mass}}}}, around 100 million stars, and a diameter of around 3300 ly.{{cite web |last1=Plait |first1=Phil |title=And the cottonball galaxies shall inherit the Universe |url=https://slate.com/technology/2011/04/and-the-cottonball-galaxies-shall-inherit-the-universe.html |website=Slate Magazine |access-date=8 August 2021 |language=en |date=25 April 2011}} It is therefore quite faint, and so was only discovered in the 20th century.

UGC 9128 is around 2.7 Mly from GR 8, which is its nearest neighbour.

UGC 9128 is a starburst galaxy, with the peak of star formation being 20–100 million years ago. It is thought to have both a halo and disc.