Dwingeloo 2

Last updated
Dwingeloo 2
Observation data (J2000 epoch)
Constellation Cassiopeia
Right ascension 02h 54m 08.47s [1]
Declination +59° 00 19.1 [1]
Heliocentric radial velocity 94 ± 1.5 km/s [2]
Galactocentric velocity241 km/s [2]
Distance ~10 Mly (3 Mpc) [3]
Group or cluster IC 342/Maffei
Apparent magnitude  (V)16.21 (V-band) [4]
Characteristics
Type IAm
Apparent size  (V)2' × 0'.8 [1]
Notable featuresCompanion of Dwingeloo 1
Other designations
PGC 101304 [1]

Dwingeloo 2 is a small irregular galaxy discovered in 1996 and located about 10 million light-years away from the Earth. Its discovery was a result of the Dwingeloo Obscured Galaxy Survey (DOGS) of the Zone of Avoidance using the Dwingeloo Radio Observatory. Dwingeloo 2 is a companion galaxy of Dwingeloo 1. [2]

Dwingeloo 2 was first detected at radio wavelengths from the 21 cm emission line of neutral atomic hydrogen (known to astronomers as HI) in the course of follow-up observations after the discovery of Dwingeloo 1. [2] Dwingeloo 2 is thought to be a member of the IC 342/Maffei Group, a galaxy group adjacent to the Local Group. [3] The galaxy recedes from the Milky Way at the speed of about 241 km/s. [2]

The visible radius of Dwingeloo 2 is approximately 2′, which at the distance of 3 Mpc corresponds to about 2 kpc. [1] Dwingeloo 2 has a well defined rotating HI disk inclined at approximately 69° with respect to observer. The distribution of the neutral hydrogen in Dwingeloo 2 is quite irregular, and it is detected as far as 3.2 kpc from the center of the galaxy. The total mass of the galaxy within this radius is estimated at 2.3 billion Solar masses, while the mass of the neutral hydrogen is estimated at 100 million Solar masses. The total mass of the galaxy is about five times less than that of Dwingeloo 1. [2]

The irregular structure of Dwingeloo 2 is likely related to its interaction with the much larger nearby galaxy Dwingeloo 1, which lies at a distance of only 24 kpc from Dwingeloo 2. [2]

Related Research Articles

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The Local Group is the galaxy group that includes the Milky Way, where Earth is located. It has a total diameter of roughly 3 megaparsecs (10 million light-years; 9×1019 kilometres), and a total mass of the order of 2×1012 solar masses (4×1042 kg). It consists of two collections of galaxies in a "dumbbell" shape; the Milky Way and its satellites form one lobe, and the Andromeda Galaxy and its satellites constitute the other. The two collections are separated by about 800 kiloparsecs (3×10^6 ly; 2×1019 km) and are moving toward one another with a velocity of 123 km/s. The group itself is a part of the larger Virgo Supercluster, which may be a part of the Laniakea Supercluster. The exact number of galaxies in the Local Group is unknown as some are occluded by the Milky Way; however, at least 80 members are known, most of which are dwarf galaxies.

<span class="mw-page-title-main">IC 342/Maffei Group</span> Galaxy cluster in the constellation of Cassiopeia

The IC 342/Maffei Group corresponds to one or two galaxy groups close to the Local Group. The member galaxies are mostly concentrated around either IC 342 or Maffei 1, which would be the brightest two galaxies in the group. The group is part of the Virgo Supercluster. However, recent studies have found that the two subgroups are unrelated; while the IC 342 group is the nearest galaxy group to the Milky Way, the Maffei 1 group is several times farther away, and is not gravitationally bound to the IC 342 group.

<span class="mw-page-title-main">Triangulum Galaxy</span> Spiral galaxy in the constellation Triangulum

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<span class="mw-page-title-main">Zone of Avoidance</span> Area of sky obscured by the Milky Way

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<span class="mw-page-title-main">Dwingeloo 1</span> Heavily obscured barred spiral galaxy in the constellation Cassiopeia

Dwingeloo 1 is a barred spiral galaxy about 10 million light-years away from the Earth, in the constellation Cassiopeia. It lies in the Zone of Avoidance and is heavily obscured by the Milky Way. The size and mass of Dwingeloo 1 are comparable to those of Triangulum Galaxy.

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<span class="mw-page-title-main">IC 342</span> Spiral galaxy in the constellation Camelopardalis

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<span class="mw-page-title-main">Antlia Dwarf</span> Galaxy in the constellation Antlia

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<span class="mw-page-title-main">UGCA 86</span> Magellanic spiral galaxy in the constellation Camelopardalis

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<span class="mw-page-title-main">Maffei 1</span> Galaxy in the constellation Cassiopeia

Maffei 1 is a massive elliptical galaxy in the constellation Cassiopeia. Once believed to be a member of the Local Group of galaxies, it is now known to belong to a separate group, the IC 342/Maffei Group. It was named after Paolo Maffei, who discovered it and the neighboring Maffei 2 in 1967 via their infrared emissions.

<span class="mw-page-title-main">Maffei 2</span> Galaxy in the constellation Cassiopeia

Maffei 2 is an intermediate spiral galaxy about 10 million light-years away in the constellation Cassiopeia. Maffei 2 and Maffei 1 were both discovered by Paolo Maffei in 1968 from their infrared emission. Maffei 2 lies in the Zone of Avoidance and is about 99.5% obscured by the Milky Way's foreground dust clouds, and as a result is barely detectable at optical wavelengths. It had been suggested soon after its discovery that Maffei 2 may be a member of the Local Group, but it is now thought to be a member of another nearby group, the IC 342/Maffei Group, the galaxy group that is the closest to the Local Group.

<span class="mw-page-title-main">Leo IV (dwarf galaxy)</span>

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Canes Venatici II or CVn II is a dwarf spheroidal galaxy situated in the Canes Venatici constellation and discovered in 2006 in data obtained by the Sloan Digital Sky Survey. The galaxy is located at a distance of about 150 kpc from the Sun and moves towards the Sun with the velocity of about 130 km/s. It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an elliptical shape with a half-light radius of about 74+14
−10
 pc
.

<span class="mw-page-title-main">Hercules (dwarf galaxy)</span> Dwarf spheroidal galaxy in the constellation Hercules

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Leo T is a dwarf galaxy situated in the Leo constellation and discovered in 2006 in the data obtained by Sloan Digital Sky Survey. The galaxy is located at the distance of about 420 kpc from the Sun and moves away from the Sun with the velocity of about 35 km/s. The velocity with respect to the Milky Way is around −60 km/s implying a slow infall onto the Milky Way. Leo T is classified as a transitional object between dwarf spheroidal galaxies (dSph) and dwarf irregular galaxies (dIrr). Its half-light radius is about 180 pc.

MB 3 is a dwarf spheroidal galaxy discovered in 1997 and located about 10 million light-years away from the Earth. It was discovered during an optical survey of the IC 342/Maffei group to which the galaxy is a member. MB3 is a companion galaxy of Dwingeloo 1 and situated in the Zone of Avoidance. MB 3 is thought to be a member of the IC 342/Maffei Group, a galaxy group adjacent to the Local Group.

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References

  1. 1 2 3 4 5 "Results for Dwingeloo 2". NASA/IPAC Extragalactic Database. Retrieved 2011-10-06.
  2. 1 2 3 4 5 6 7 Burton, W.B.; Verheijen, M. A. W.; Kraan-Korteweg, R. C.; Henning, P. A. (1996). "Neutral hydrogen in the nearby galaxies Dwingeloo 1 and Dwingeloo 2". Astronomy and Astrophysics. 309: 687–701. arXiv: astro-ph/9511020 . Bibcode:1996A&A...309..687B.
  3. 1 2 Karachentsev, I. D. (2005). "The Local Group and Other Neighboring Galaxy Groups". The Astronomical Journal. 129 (1): 178–188. arXiv: astro-ph/0410065 . Bibcode:2005AJ....129..178K. doi:10.1086/426368. S2CID   119385141.
  4. Buta, R. J.; McCall, M. L. (1999). "The IC 342/Maffei Group Revealed". The Astrophysical Journal Supplement Series. 124 (1): 33–93. Bibcode:1999ApJS..124...33B. doi: 10.1086/313255 .