Andromeda IX

{{Short description|Dwarf spheroidal galaxy in the constellation Andromeda}}

{{Infobox Galaxy

| name = Andromeda IX

| epoch = J2000

| type = dE{{cite simbad

| work=NASA/IPAC Extragalactic Database

| title=Results for Andromeda IX

| url=http://nedwww.ipac.caltech.edu/

| access-date=2006-11-29 }}

| ra = {{RA|00|52|53.0}}

| dec = {{DEC|+43|11|45}}

| dist_ly = 2.50 ± 0.08 Mly (766 ± 25 kpc)

| z = -216 ± ? km/s

| appmag_v = 16.2

| size_v =

| constellation name = Andromeda

| notes = Satellite galaxy
M31

| names = And IX, PGC 4689222{{cite simbad

| title=NAME Andromeda IX

| access-date=2006-11-29}}

}}

Andromeda IX (And 9) is a dwarf spheroidal satellite of the Andromeda Galaxy. It was discovered in 2004 by resolved stellar photometry from the Sloan Digital Sky Survey (SDSS), by Zucker et al. (2004).{{cite journal

| author=McConnachie, A. W.

| author2=Irwin, M. J.

| author3=Ferguson, A. M. N.

| author4=Ibata, R. A.

| author5=Lewis, G. F.

| author6=Tanvir, N.

| title=Distances and metallicities for 17 Local Group galaxies

| journal=Monthly Notices of the Royal Astronomical Society

| date=2005

| volume=356

| issue=4

| pages=979–997

| bibcode=2005MNRAS.356..979M

| doi=10.1111/j.1365-2966.2004.08514.x | doi-access=free

|arxiv = astro-ph/0410489 }} At the time of its discovery, it was the galaxy with the lowest known surface brightness, Σ_V ≃ 26.8mags arcsec⁻² and the faintest galaxy known from its intrinsic absolute brightness.

It was found from data acquired within an SDSS scan along the major axis of M31, on October 5, 2002. Its distance was estimated to be almost exactly the same as that of M31 by McConnacrchie et al. (2005). Star formation history and dust production in Andromeda IX, as the closest satellite to M31, have also been investigated by Abdollahi et al. (2023).{{cite journal

|display-authors=etal

| author=Abdollahi, H.

| author2=Javadi, A.

| title=The Isaac Newton Telescope Monitoring Survey of Local Group Dwarf Galaxies. VI. The Star Formation History and Dust Production in Andromeda IX

| journal= The Astrophysical Journal

| date=2023

| volume=948

| page=63

| doi=10.3847/1538-4357/acbbc9 | doi-access=free

| hdl=10852/103165

| hdl-access=free

| arxiv=2302.07674

}}