DDO 44
{{Short description|Dwarf spheroidal galaxy in the constellation Camelopardalis}}
{{Infobox galaxy
| name = DDO 44
| image = UGCA 133 (or DDO 44) color cutout hst 10915 0x acs wfc f814w f475w sci.jpg
| image_size = 250px
| caption = An image of DDO 44, as taken by the Hubble Space Telescope
| epoch = J2000
| constellation name = Camelopardalis
| ra = {{RA|07|34|11.5}} {{cite web |title=UGCA 133 -- Galaxy |url=http://simbad.u-strasbg.fr/simbad/sim-id?Ident=UGCA+133 |publisher=SIMBAD |access-date=19 August 2020}}
| dist_ly = 9.82 ± 0.59 Mly
| type = dSph {{sfn|Karachentsev et al.|2011|p=L34}}
| notes =
| names = UGCA 133, Anon 0729+66, LEDA 21302, KK98a 61, KK98a 072913.1+665940
}}
DDO 44 (or UGCA 133) is a dwarf spheroidal galaxy in the M81 Group, believed to be a satellite galaxy of the nearby NGC 2403.
Structure
DDO 44 is a relatively large dwarf galaxy, and it has been observed to possess a tidal tail extending at least 50,000 parsecs from its center.{{sfn|Carlin et al.|2019|p=1}} It has an estimated metallicity ([Fe/H]) of -1.54 ± 0.14.{{sfn|Alonso‐García et al.|2006|p=580}} Due to its proximity and relative velocity to the larger NGC 2403, it is believed to be NGC 2403's satellite galaxy.{{sfn|Carlin et al.|2019|p=2}} Stellar streams has been observed to originate from DDO 44, flowing towards and away for NGC 2403, indicating tidal disruptions.{{sfn|Carlin et al.|2019|p=4}} Around 20 percent of the galaxy's stars are believed to be of intermediate age (between 2-8 Gya),{{sfn|Alonso‐García et al.|2006|p=580}} with the most recent stellar formation being estimated at 300 Mya due to a lack of young bright blue stars.{{sfn|Karachentsev et al.|1999|p=5}} This lack of bright stars caused DDO 44 to have a relatively low level of brightness.{{sfn|Alonso‐García et al.|2006|p=580}}
It is located approximately 3 million parsecs away from the Milky Way,{{sfn|Alonso‐García et al.|2006|p=580}}{{sfn|Karachentsev et al.|1999|p=7}} and 79 arcminutes towards north-northwest from NGC 2403 (or approximately 75 kpc).{{sfn|Karachentsev et al.|2011|p=L33}}{{sfn|Alonso‐García et al.|2006|p=581}} Mass estimates based on luminosity measurements give a galactic mass of 2×107–6×107 M☉.{{sfn|Carlin et al.|2019|p=8}} This makes DDO 44 by far NGC 2403's most massive known satellite galaxy, with the other known satellite galaxy (MADCASH J074238+652501-dw) having a mass of just ~105 M☉.{{sfn|Carlin et al.|2019|p=8}} HI observations place an upper limit for DDO 44's hydrogen gas mass at 4×105 M☉.{{sfn|Karachentsev et al.|2011|p=L34}}
References
{{Reflist}}
Bibliography
- {{cite journal |last1=Alonso-García |first1=Javier |last2=Mateo |first2=Mario |last3=Aparicio |first3=Antonio |title=DDO 44 and UGC 4998: Distances, Metallicities, and Star Formation Histories |journal=Publications of the Astronomical Society of the Pacific |date=2006 |volume=118 |issue=842 |pages=580–589 |doi=10.1086/502984 |bibcode=2006PASP..118..580A |s2cid=120814156 |language=en |issn=0004-6280|ref={{harvid|Alonso‐García et al.|2006}}|doi-access=free }}
- {{cite journal |last1=Carlin |first1=Jeffrey L. |last2=Garling |first2=Christopher T. |last3=Peter |first3=Annika H. G. |last4=Crnojević |first4=Denija |last5=Forbes |first5=Duncan A. |last6=Hargis |first6=Jonathan R. |last7=Mutlu-Pakdil |first7=Burçin |last8=Pucha |first8=Ragadeepika |last9=Romanowsky |first9=Aaron J. |last10=Sand |first10=David J.|author11-link=Kristine Spekkens |last11=Spekkens |first11=Kristine |last12=Strader |first12=Jay |last13=Willman |first13=Beth |title=Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44 |journal=The Astrophysical Journal |date=2019 |volume=886 |issue=2 |page=109 |doi=10.3847/1538-4357/ab4c32 |arxiv=1906.08260 |bibcode=2019ApJ...886..109C |s2cid=195218404 |issn=1538-4357|ref={{harvid|Carlin et al.|2019}} |doi-access=free }}
- {{cite journal |last1=Karachentsev |first1=I. D. |last2=Sharina |first2=M. E. |last3=Grebel |first3=E. K. |last4=Dolphin |first4=A. E. |last5=Geisler |first5=D. |last6=Guhathakurta |first6=P. |last7=Hodge |first7=P. W. |last8=Karachentseva |first8=V. E. |last9=Sarajedini |first9=A. |last10=Seitzer |first10=P. |title=The dwarf spheroidal galaxy DDO 44: stellar populations and distance |journal=Astronomy and Astrophysics |date=1999 |volume=352|page=399 |arxiv=astro-ph/9910402 |bibcode=1999A&A...352..399K |ref={{harvid|Karachentsev et al.|1999}} }}
- {{cite journal |last1=Karachentsev |first1=Igor |last2=Kaisina |first2=Elena |last3=Kaisin |first3=Serafim |last4=Makarova |first4=Lidia |title=Emission sparks around M 81 and in some dwarf spheroidal galaxies: Emission sparks in dSph galaxies |journal=Monthly Notices of the Royal Astronomical Society: Letters |date=2011 |volume=415 |issue=1 |pages=L31–L34 |doi=10.1111/j.1745-3933.2011.01069.x |ref={{harvid|Karachentsev et al.|2011}}|doi-access=free |arxiv=1104.5318 }}
{{Camelopardalis}}
{{Sky|07|34|11.5|+|66|52|47|1000000}}
{{DEFAULTSORT:DDO 44}}