DDO 190

{{Short description|Dwarf galaxy}} {{Infobox galaxy | name = DDO 190 | image = UGC 9240 galaxy HST.jpg | image_size = 250px | caption = The dwarf galaxy with pockets of ionised gas, seen as blue | epoch = J2000 | pronounce = | constellation name = | ra = {{RA|14|24|43.08}}<ref name=GaiaDR2>{{cite DR2|1492921389322844032}}</ref> | dec = {{DEC|+44|31|31.8}}<ref name=GaiaDR2/> | z = 0.000500<ref name=SIMBAD/> | h_radial_v = 150.0 ± 4.0 km/s<ref name=SIMBAD/> | gal_v = | dist_ly = {{convert|9.10|e6ly|Mpc|abbr=on|lk=on}}{{hub|0.73}} | group_cluster = [[M94 Group]] | type = IAm | mass = {{Val|5|e=7}} | mass_light_ratio =  | stars = | appmag_v = 13.25 | absmag_v = -14.19 | size_v = | notes = | names = {{odlist|UGC=9240|MCG=+08-26-030|PGC=51472}}<ref name=SIMBAD>{{cite simbad|title=DDO 190|accessdate=2021-02-22}}</ref> | references = }} '''DDO 190''' (or '''UGC 9240''') is a [[dwarf galaxy|dwarf]] [[irregular galaxy]] in the vicinity of the [[Milky Way]], as it is relatively small and lacks clear structure. It is {{convert|9.10|e6ly|Mpc}} away from Earth and lies out of the [[Local Group]], determined by the [[tip of the red giant branch]] method.<ref name="BPDS">{{Cite journal |url = http://www.aanda.org/articles/aa/pdf/2006/08/aa2829-05.pdf |title = The C star population of DDO 190 |first1 = P. |last1 = Battinelli |first2 = S. |last2 = Demers |journal = Astronomy & Astrophysics |year = 2006 |volume = 447 |issue = 2 |pages = 473–480 |publisher = ESO |doi = 10.1051/0004-6361:20052829 |archive-url = https://web.archive.org/web/20141110193355/http://www.aanda.org/articles/aa/pdf/2006/08/aa2829-05.pdf |archive-date = 2014-11-10 |url-status = dead |access-date = 2012-08-18 |quote = The HI mass of DDO 190, estimated at 5 × 107 solar masses by Stil & Israel (2002a) is normal for a galaxy of its luminosity. |bibcode = 2006A&A...447..473B |s2cid = 59497374 }}</ref> The outskirts of the galaxy are harbouring older (reddish) stars, while the centre is crowded with younger (bluish) stars. Heated gas is observed at several places.<ref name="NASA" /> DDO 190 still experiences some active star formation. The galaxy is categorised as a Magellanic dwarf galaxy of morphological type [[Irregular galaxy|Im]]. Its [[metallicity]] is [Fe/H] = −1.55 ± 0.12.<ref name="BPDS" />

DDO 190 is small, but not tiny: about 15,000 light years across—about 1/6 the size of our galaxy. It is also well outside the [[Local Group]], which contains nearby galaxies (the Andromeda galaxy is less than 3 million light years distant from Earth, for comparison), and is instead thought to be part of the [[M94 Group|M94 galaxy group]]. But if true it is fairly isolated even from the others on its team; the nearest neighbor appears to be another dwarf galaxy, [[DDO 187]], at a distance of {{convert|3|e6ly|Mpc}}.<ref name="NASA">{{Cite web |url = http://www.nasa.gov/ |title = Galactic Island |date = 2012-08-17 |publisher = [[NASA]] |archive-url = https://web.archive.org/web/20120817214028/http://www.nasa.gov/ |archive-date = 2012-08-17 |access-date = 2012-08-18 |url-status = bot: unknown }}</ref>

== History == The galaxy was discovered by the [[Canadians|Canadian]] astronomer [[Sidney van den Bergh]] in 1959 and put in the [[David Dunlap Observatory|DDO]] catalogue.<ref name="NASA" />

== References == {{Reflist}}

[[Category:UGC objects|9240]] [[Category:Dwarf galaxies]] [[Category:Boötes]] [[Category:Astronomical objects discovered in 1959]]