Sagittarius Dwarf Irregular Galaxy

{{Short description|Dwarf galaxy in the constellation of Sagittarius}}

{{Distinguish|text=Sagittarius Dwarf Spheroidal Galaxy (SagDEG), a satellite galaxy of the Milky Way}}

{{Infobox Galaxy

| name = SagDIG

| image = SagDIG.jpg

| image_size = 250px

| caption = SagDIG by Hubble Space Telescope

| credit =

| type = IB(s)m{{cite web

| title=NASA/IPAC Extragalactic Database

| work=Results for Sagittarius Dwarf Irregular

| url=http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Sagittarius+Dwarf+Irregular#ObjNo1

| access-date=2007-03-15 }} V (Dwarf irregular galaxy)

| epoch = J2000

| ra = {{RA|19|29|59.0}}

| dec = {{DEC|-17|40|41}}

| dist_ly = 3.39±0.23 Mly (1.04±0.07 Mpc){{cite journal

| author1=Karachentsev, I.D.

| author2=Karachentseva, V.E.

| author3=Hutchmeier, W.K.

| author4=Makarov, D.I.

| title=A Catalog of Neighboring Galaxies

| journal=Astronomical Journal

| date=2004

| volume=127

| issue=4

| pages=2031–2068

| bibcode=2004AJ....127.2031K

| doi=10.1086/382905| doi-access=free

}}{{cite journal

| author1=Karachentsev, I.D.

| author2=Kashibadze, O.G.

| title=Masses of the local group and of the M81 group estimated from distortions in the local velocity field

| journal=Astrophysics

| date=2006

| volume=49

| issue=1

| pages=3–18

| bibcode=2006Ap.....49....3K

| doi=10.1007/s10511-006-0002-6| s2cid=120973010

}}

| appmag_v = 15.5

| size_v = 2.9{{prime}} × 2.1{{prime}}

| constellation name = Sagittarius

| z = −79±1 km/s

| notes =

| names = Sagittarius Dwarf Irregular, SGR Dwarf,
ESO594-G004, PGC 63287, Kowal's Object

}}

The Sagittarius Dwarf Irregular Galaxy (SagDIG) is a dwarf galaxy in the constellation of Sagittarius. It lies about 3.4 million light-years away. It was discovered by Cesarsky{{who?|date=March 2025}} et al. on a photographic plate taken for the ESO (B) Atlas on 13 June 1977 using the ESO 1 meter Schmidt telescope.

The SagDIG is thought to be the member of the Local Group most remote from the Local Group's barycenter. It is only slightly outside the zero-velocity surface of the Local Group.{{Cite journal

| last1 = van den Bergh

| first1 = Sidney

| authorlink1 = Sidney van den Bergh

| title = Updated Information on the Local Group

| date = April 2000

| journal = The Publications of the Astronomical Society of the Pacific

| volume = 112

| issue = 770

| bibcode = 2000PASP..112..529V

| pages = 529–536

| doi = 10.1086/316548

|arxiv = astro-ph/0001040 | s2cid = 1805423

}}

SagDIG is a much more luminous galaxy than the Aquarius Dwarf and it has been through a prolonged period of star formation.Momany et al. 2005. This has resulted in it containing a rich intermediate-age population of stars. Twenty-seven candidate carbon stars have been identified inside SagDIG. Analysis shows that the underlying stellar population of SagDIG is metal-poor (at least [Fe/H] ≤ −1.3). Further, the population is young, with the most likely average age between 4 and 8 billion years for the dominant population.{{Cite journal

| last1 = Gullieuszik

| first1 = M.

| last2 = Rejkuba

| first2 = M.

| last3 = Cioni

| first3 = M. R.

| last4 = Habing

| first4 = H. J.

| last5 = Held

| first5 = E. V.

| title = Near-infrared photometry of carbon stars in the Sagittarius dwarf irregular galaxy and DDO 210

| date = November 2007