Dwingeloo 1

Dwingeloo 1 is a bar-spiral galaxy of type SB (s) cd at a distance of about 10 million light years from our solar system . The galaxy is located in the constellation of Cassiopeia and lies in the middle of the galactic plane in the so-called Zone of Avoidance of the Milky Way , known for obscuring the galactic background with a large number of stars and interstellar dust. The mass and size of the spiral galaxy Dwingeloo 1 are comparable to the triangular nebula .

Dwingeloo 1 owns the two well-known satellite galaxies Dwingeloo 2 and MB 3 and is a member of the Maffei group , a group of galaxies in the immediate vicinity of our local group .

discovery

The Dwingeloo radio telescope near the Dutch village of Dwingeloo

Dwingeloo 1 was in year 1994 during the screening of the dwingeloo Obscured Galaxy Survey discovered (DOGS), the neutral for signs hydrogen gas in the so-called zone of Avoidance of the Milky Way by its radio wave emissions from the 21 cm emission line investigated.

The galaxy was actually recorded earlier in the same year when the Palomar Sky Survey was surveyed, but was not recognized as a galaxy, but categorized as an insignificant peculiarity.

Dwingeloo 1 was discovered in the same year independently of another astronomical research team who worked with the Effelsberg radio telescope .

After the discovery, the galaxy was classified as a bar-spiral galaxy, its distance determined to be 3 Mpc. In terms of its dimensions, such as total mass and size, it is roughly comparable to the triangular nebula.

Dwingeloo 1 got its name from the Dwingeloo radio telescope in the Netherlands , which was used for the DOGS survey and with which the galaxy was first discovered.

Distance and group membership

Dwingeloo 1 is a galaxy that is heavily covered by the Milky Way foreground, which makes it extremely difficult to determine the distance . Initial estimates were made soon after their discovery and were based on the Tully-Fisher relationship and came to 3 Mpc. Later measurements showed slightly higher values of 3.5 to 4.0 Mpc.

In 1999 an estimate was published claiming to have measured the distance at 5 Mpc. This was based on the infrared Tully – Fisher relationship. As of 2011 , the most likely distance from Dwingeloo 1 is again approximately 3 Mpc, in line with her membership in the Maffei group .

Dwingeloo 1 has two smaller satellite galaxies. The first known as Dwingeloo 2 is an irregular dwarf galaxy while the other MB 3 is likely a spheroid dwarf galaxy. All three galaxies are part of the Maffei group of galaxies.

properties

shape

As a barred spiral galaxy, Dwingeloo 1 has a central bar and two clearly defined spiral arms that go off the bar at right angles and wind counter-clockwise. The length of the arms is up to 180 °. The disk of the galaxy is inclined at an angle of 50 ° in relation to the observer .

The galaxy is moving away from the Milky Way at a speed of about 256 k m / s .

composition

The visible radius of Dwingeloo 1 is about 4.2 arc minutes, which at a distance of 3 Mpc corresponds to an absolute value of 4 kpc. Neutral hydrogen gas can be observed up to 6 kpc or 7.5 arc minutes. The total mass up to the latter becomes about 31 billion M _☉ . This makes it a quarter of the total mass of the Milky Way.

The distribution of the neutral hydrogen is typically relatively flat for bar spirals with a minimum in the center of the galaxy or along the bars. The total mass of the gas in Dwingeloo 1 will be 370-450 million M _☉ estimated. This means that this galaxy is one of the galaxies with less gas. The total mass of molecular hydrogen is not higher than 10% of the total neutral hydrogen. Observations in the visible part of the spectrum show around 15 H-II regions that are along the spiral arms.

Web links

Individual evidence

↑ ^a ^b ^c ^d NASA / IPAC Extragalactic Database . In: Results for Dwingeloo 1 . Retrieved October 24, 2011.
^ ^A ^b Buta, RJ, McCall, ML: "The IC 342 / Maffei Group Revealed" . In: The Astrophysical Journal Supplement Series . 124, 1999, p. 33. doi : 10.1086 / 313255 .
↑ ^a ^b ^c ^d ^e W.B. Burton, Verheijen, MAW; Kraan-Korteweg, RC; Henning, PA: Neutral hydrogen in the nearby galaxies Dwingeloo 1 and Dwingeloo 2 . In: Astronomy and Astrophysics . 309, 1996, pp. 687-701. arxiv : astro-ph / 9511020 . bibcode : 1996A & A ... 309..687B .
↑ ^a ^b ^c ^d Karachentsev, ID: "The Local Group and Other Neighboring Galaxy Groups" . In: The Astronomical Journal . 129, 2005, p. 178. doi : 10.1086 / 426368 .
↑ ^a ^b ^c ^d ^e ^f ^g Kraan-Korteweg, RC, Loan, AJ; Burton, WB; Lahav, O .; Ferguson, HC; Henning, PA; Lynden-Bell, D .: "Discovery of a nearby spiral galaxy behind the Milky Way" . In: Nature . 372 (6501), 1994, p. 77. doi : 10.1038 / 372077a0 .
↑ ^a ^b W.K. Huchtmeier, Lercher, G .; Seeberger, R .; Saurer, W .; Weinberger, R .: Two new possible members of the IC342-Maffei1 / 2 group of galaxies . In: Astronomy and Astrophysics . 293L, 1995, pp. L33-L36. bibcode : 1995A & A ... 293L..33H .
↑ ^a ^b ^c A.J. Loan, Maddox, SJ; Lahav, O. et al. : Optical observations of Dwingeloo 1, a nearby barred spiral galaxy behind the Milky Way . In: Monthly Notices of the Royal Astronomical Society . 280, 1996, pp. 537-549. bibcode : 1996MNRAS.280..537L .
↑ Ivanov, VD, Alonso-Herrero, A .; Rieke, MJ; McCarthy, D .: "An Infrared Determination of the Reddening and Distance to Dwingeloo 1" . In: The Astronomical Journal . 118 (2), 1999, p. 826. doi : 10.1086 / 300986 .
↑ Nario Kuno, Vila-Vilaro, Baltasar; Nishiyama, Kohta: CO Observations of a Galaxy behind the Galactic Plane, Dwingeloo 1 . In: Publ. Of the Astronomical Society of Japan . 48, 1996, pp. 19-22. bibcode : 1996PASJ ... 48 ... 19K .

[ned-1] NASA / IPAC Extragalactic Database . In: Results for Dwingeloo 1 . Retrieved October 24, 2011.

[Buta1999-2] A ^b Buta, RJ, McCall, ML: "The IC 342 / Maffei Group Revealed" . In: The Astrophysical Journal Supplement Series . 124, 1999, p. 33. doi : 10.1086 / 313255 .

[Burton1996-3] W.B. Burton, Verheijen, MAW; Kraan-Korteweg, RC; Henning, PA: Neutral hydrogen in the nearby galaxies Dwingeloo 1 and Dwingeloo 2 . In: Astronomy and Astrophysics . 309, 1996, pp. 687-701. arxiv : astro-ph / 9511020 . bibcode : 1996A & A ... 309..687B .

[Karachentsev2005-4] Karachentsev, ID: "The Local Group and Other Neighboring Galaxy Groups" . In: The Astronomical Journal . 129, 2005, p. 178. doi : 10.1086 / 426368 .

[Kraan-Korteweg1994-5] ↑ ^a ^b ^c ^d ^e ^f ^g Kraan-Korteweg, RC, Loan, AJ; Burton, WB; Lahav, O .; Ferguson, HC; Henning, PA; Lynden-Bell, D .: "Discovery of a nearby spiral galaxy behind the Milky Way" . In: Nature . 372 (6501), 1994, p. 77. doi : 10.1038 / 372077a0 .

[Huchtmeier1995-6] W.K. Huchtmeier, Lercher, G .; Seeberger, R .; Saurer, W .; Weinberger, R .: Two new possible members of the IC342-Maffei1 / 2 group of galaxies . In: Astronomy and Astrophysics . 293L, 1995, pp. L33-L36. bibcode : 1995A & A ... 293L..33H .

[Loan1996-7] A.J. Loan, Maddox, SJ; Lahav, O. et al. : Optical observations of Dwingeloo 1, a nearby barred spiral galaxy behind the Milky Way . In: Monthly Notices of the Royal Astronomical Society . 280, 1996, pp. 537-549. bibcode : 1996MNRAS.280..537L .

[Ivanov1999-8] Ivanov, VD, Alonso-Herrero, A .; Rieke, MJ; McCarthy, D .: "An Infrared Determination of the Reddening and Distance to Dwingeloo 1" . In: The Astronomical Journal . 118 (2), 1999, p. 826. doi : 10.1086 / 300986 .

[Kuno1996-9] Nario Kuno, Vila-Vilaro, Baltasar; Nishiyama, Kohta: CO Observations of a Galaxy behind the Galactic Plane, Dwingeloo 1 . In: Publ. Of the Astronomical Society of Japan . 48, 1996, pp. 19-22. bibcode : 1996PASJ ... 48 ... 19K .