DDO 44

DDO 44
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
Declination	+66° 52′ 47″
Redshift	0.000711
Distance	9.82 ± 0.59 Mly
Apparent magnitude (V)	15.6
Characteristics
Type	dSph
Apparent size (V)	1′.51 × 0′.998
Other designations
	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.^[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] H_I observations place an upper limit for DDO 44's hydrogen gas mass at 4×10⁵ M_☉.^[3]

References

^ ^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

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.

[simbad-1] ^ ^a ^b ^c ^d ^e ^f "UGCA 133 -- Galaxy". SIMBAD. Retrieved 19 August 2020.

[2] "NASA/IPAC Intergalactic Database". Retrieved 20 August 2020.

[FOOTNOTEKarachentsev_et_al.2011L34-3] Karachentsev et al. 2011, p. L34.

[FOOTNOTECarlin_et_al.20191-4] Carlin et al. 2019, p. 1.

[FOOTNOTEAlonso‐García_et_al.2006580-5] Alonso‐García et al. 2006, p. 580.

[FOOTNOTECarlin_et_al.20192-6] Carlin et al. 2019, p. 2.

[FOOTNOTECarlin_et_al.20194-7] Carlin et al. 2019, p. 4.

[FOOTNOTEKarachentsev_et_al.19995-8] Karachentsev et al. 1999, p. 5.

[FOOTNOTEKarachentsev_et_al.19997-9] Karachentsev et al. 1999, p. 7.

[FOOTNOTEKarachentsev_et_al.2011L33-10] Karachentsev et al. 2011, p. L33.

[FOOTNOTEAlonso‐García_et_al.2006581-11] Alonso‐García et al. 2006, p. 581.

[FOOTNOTECarlin_et_al.20198-12] Carlin et al. 2019, p. 8.

[1]