Summary
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.
| DDO 44 | |
|---|---|
 An image of DDO 44, as taken by the Hubble Space Telescope | |
| Observation data (J2000 epoch) | |
| Constellation | Camelopardalis |
| Right ascension | 07h 34m 11.5s [1] |
| Declination | +66° 52′ 47″ [1] |
| Redshift | 0.000711 [1] |
| Distance | 9.82 ± 0.59 Mly |
| Apparent magnitude (V) | 15.6 [2] |
| Characteristics | |
| Type | dSph [3] |
| Apparent size (V) | 1′.51 × 0′.998 [1] |
| Other designations | |
| UGCA 133, Anon 0729+66, LEDA 21302, KK98a 61, KK98a 072913.1+665940[1] | |
Structure edit
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.[4] It has an estimated metallicity ([Fe/H]) of -1.54 ± 0.14.[5] Due to its proximity and relative velocity to the larger NGC 2403, it is believed to be NGC 2403's satellite galaxy.[6] Stellar streams has been observed to originate from DDO 44, flowing towards and away for NGC 2403, indicating tidal disruptions.[7] Around 20 percent of the galaxy's stars are believed to be of intermediate age (between 2-8 Gya),[5] with the most recent stellar formation being estimated at 300 Mya due to a lack of young bright blue stars.[8] This lack of bright stars caused DDO 44 to have a relatively low level of brightness.[5]
It is located approximately 3 million parsecs away from the Milky Way,[5][9] and 79 arcminutes towards north-northwest from NGC 2403 (or approximately 75 kpc).[10][11] Mass estimates based on luminosity measurements give a galactic mass of 2×107–6×107 M☉.[12] 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☉.[12] HI observations place an upper limit for DDO 44's hydrogen gas mass at 4×105 M☉.[3]
References edit
- ^ a b c d e f "UGCA 133 -- Galaxy". SIMBAD. Retrieved 19 August 2020.
- ^ "NASA/IPAC Intergalactic Database". Retrieved 20 August 2020.
- ^ a b Karachentsev et al. 2011, p. L34.
- ^ Carlin et al. 2019, p. 1.
- ^ a b c d Alonso‐García et al. 2006, p. 580.
- ^ Carlin et al. 2019, p. 2.
- ^ Carlin et al. 2019, p. 4.
- ^ Karachentsev et al. 1999, p. 5.
- ^ Karachentsev et al. 1999, p. 7.
- ^ Karachentsev et al. 2011, p. L33.
- ^ Alonso‐García et al. 2006, p. 581.
- ^ a b Carlin et al. 2019, p. 8.
Bibliography edit
- Alonso‐García, Javier; Mateo, Mario; Aparicio, Antonio (2006). "DDO 44 and UGC 4998: Distances, Metallicities, and Star Formation Histories". Publications of the Astronomical Society of the Pacific. 118 (842): 580–589. Bibcode:2006PASP..118..580A. doi:10.1086/502984. ISSN 0004-6280. S2CID 120814156.
- Carlin, Jeffrey L.; Garling, Christopher T.; Peter, Annika H. G.; Crnojević, Denija; Forbes, Duncan A.; Hargis, Jonathan R.; Mutlu-Pakdil, Burçin; Pucha, Ragadeepika; Romanowsky, Aaron J.; Sand, David J.; Spekkens, Kristine; Strader, Jay; Willman, Beth (2019). "Tidal Destruction in a Low-mass Galaxy Environment: The Discovery of Tidal Tails around DDO 44". The Astrophysical Journal. 886 (2): 109. arXiv:1906.08260. Bibcode:2019ApJ...886..109C. doi:10.3847/1538-4357/ab4c32. ISSN 1538-4357. S2CID 195218404.
- Karachentsev, I. D.; Sharina, M. E.; Grebel, E. K.; Dolphin, A. E.; Geisler, D.; Guhathakurta, P.; Hodge, P. W.; Karachentseva, V. E.; Sarajedini, A.; Seitzer, P. (1999). "The dwarf spheroidal galaxy DDO 44: stellar populations and distance". Astronomy and Astrophysics. 352: 399. arXiv:astro-ph/9910402. Bibcode:1999A&A...352..399K.
- Karachentsev, Igor; Kaisina, Elena; Kaisin, Serafim; Makarova, Lidia (2011). "Emission sparks around M 81 and in some dwarf spheroidal galaxies: Emission sparks in dSph galaxies". Monthly Notices of the Royal Astronomical Society: Letters. 415 (1): L31–L34. arXiv:1104.5318. doi:10.1111/j.1745-3933.2011.01069.x.