Dwingeloo 1
Encyclopedia
Dwingeloo 1 is a barred spiral galaxy
about 10 million light-year
s 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
.
Dwingeloo 1 has two smaller satellite galaxies
: Dwingeloo 2
and MB 3
and is a member of the IC 342/Maffei Group of galaxies.
. In this zone gas and dust in the disk of the Milky Way galaxy block the light from the galaxies lying behind it.
The galaxy was, however, first noted as an unremarkable feature on Palomar Sky Survey plates earlier in the same year, but was not recognized as such. It was also independently discovered a few weeks later by another team of astronomers working with Effelsberg 100-m Radio Telescope.
After the discovery Dwingeloo 1 was classified as a barred spiral galaxy
. The distance to it was found to be approximately 3 Mpc. In its overall size and mass the galaxy is comparable to Triangulum Galaxy
.
Dwingeloo 1 was eventually named after the 25m radio telescope
in the Netherlands
that was used in the DOGS survey and first detected it.
In 1999 another estimate was published claiming the distance of more than 5 Mpc. It was based on the infrared Tully–Fisher relation. As of 2011 the most likely distance to Dwingeloo 1 is thought to be approximately 3 Mpc based on its likely membership in the IC 342/Maffei group.
Dwingeloo 1 has two smaller satellite galaxi
es. The first one known as Dwingeloo 2
is an irregular galaxy
and the second MB3
is likely a dwarf spheroidal galaxy
. Dwingeloo 1 is a member of the IC 342/Maffei Group of galaxies.
The visible radius of Dwingeloo 1 is approximately 4.2′, which at the distance of 3 Mpc corresponds to about 4 kpc. The neutral hydrogen is detected as far as 6 kpc from the center. The total mass of the galaxy within the latter radius is estimated at 25 billion Solar masses. The total mass of the galaxy is about four times that of the Milky Way.
The distribution of the neutral hydrogen in Dwingeloo 1 is typical for barred spiral galaxies—rather flat with a minimum in the center or along the bar. Its total mass is estimated at 370–450 million Solar mass
es. Dwingeloo 1 is a molecular gas-poor galaxy. The total mass of the molecular hydrogen does not exceed 10% of this value. Optical observations detected around 15 H II region
s situated mainly along the spiral arms.
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies...
about 10 million light-year
Light-year
A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...
s away from the Earth, in the constellation
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
Cassiopeia
Cassiopeia (constellation)
Cassiopeia is a constellation in the northern sky, named after the vain queen Cassiopeia in Greek mythology, who boasted about her unrivalled beauty. Cassiopea was one of the 48 constellations listed by the 2nd century Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today...
. It lies in the Zone of Avoidance
Zone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
and is heavily obscured by the Milky Way
Milky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
. The size and mass of Dwingeloo 1 are comparable to those of Triangulum Galaxy
Triangulum Galaxy
The Triangulum Galaxy is a spiral galaxy approximately 3 million light years from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC 598, and is sometimes informally referred to as the Pinwheel Galaxy, a nickname it shares with Messier 101...
.
Dwingeloo 1 has two smaller satellite galaxies
Satellite galaxy
A satellite galaxy orbits a larger galaxy due to gravitational attraction. Although a galaxy is made of a large number of objects which are not connected to each other, it has a center of mass, which represents a weighted average of the positions of each component object...
: Dwingeloo 2
Dwingeloo 2
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 Dwingeloo Obscured Galaxy Survey of the Zone of Avoidance...
and MB 3
MB 3
MB3 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...
and is a member of the IC 342/Maffei Group of galaxies.
Discovery
The Dwingeloo 1 galaxy was discovered in 1994 by the Dwingeloo Obscured Galaxy Survey (DOGS), which searched for neutral hydrogen (HI) radio emissions at the wavelength of 21 cm from objects in the Zone of AvoidanceZone of Avoidance
The Zone of Avoidance is the area of the night sky that is obscured by our own galaxy, the Milky Way.-Term:The ZOA was originally called the "Zone of Few Nebulae" in an 1878 paper by English astronomer Richard Proctor that referred to the distribution of "nebulae" in Sir John Herschel's General...
. In this zone gas and dust in the disk of the Milky Way galaxy block the light from the galaxies lying behind it.
The galaxy was, however, first noted as an unremarkable feature on Palomar Sky Survey plates earlier in the same year, but was not recognized as such. It was also independently discovered a few weeks later by another team of astronomers working with Effelsberg 100-m Radio Telescope.
After the discovery Dwingeloo 1 was classified as a barred spiral galaxy
Barred spiral galaxy
A barred spiral galaxy is a spiral galaxy with a central bar-shaped structure composed of stars. Bars are found in approximately two-thirds of all spiral galaxies...
. The distance to it was found to be approximately 3 Mpc. In its overall size and mass the galaxy is comparable to Triangulum Galaxy
Triangulum Galaxy
The Triangulum Galaxy is a spiral galaxy approximately 3 million light years from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC 598, and is sometimes informally referred to as the Pinwheel Galaxy, a nickname it shares with Messier 101...
.
Dwingeloo 1 was eventually named after the 25m radio telescope
Dwingeloo Radio Observatory
The Dwingeloo Radio Observatory , is a single dish radio telescope with a diameter of 25 m. Construction started in 1954, the telescope was completed in 1956. At that time it was the largest radio telescope in the world...
in the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
that was used in the DOGS survey and first detected it.
Distance and group membership
Dwingeloo 1 is a highly obscured galaxy, which makes distance determination a difficult problem. The initial estimate made soon after the discovery and based on the Tully–Fisher relation was about 3 Mpc. Later it was slightly increased to 3.5–4 Mpc.In 1999 another estimate was published claiming the distance of more than 5 Mpc. It was based on the infrared Tully–Fisher relation. As of 2011 the most likely distance to Dwingeloo 1 is thought to be approximately 3 Mpc based on its likely membership in the IC 342/Maffei group.
Dwingeloo 1 has two smaller satellite galaxi
Satellite galaxy
A satellite galaxy orbits a larger galaxy due to gravitational attraction. Although a galaxy is made of a large number of objects which are not connected to each other, it has a center of mass, which represents a weighted average of the positions of each component object...
es. The first one known as Dwingeloo 2
Dwingeloo 2
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 Dwingeloo Obscured Galaxy Survey of the Zone of Avoidance...
is an irregular galaxy
Irregular galaxy
An irregular galaxy is a galaxy that does not have a distinct regular shape, like a spiral or an elliptical galaxy. The shape of an irregular galaxy is uncommon – they do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a...
and the second MB3
MB3
MB3 may refer to:* MB3 mountain bike model manufactured by Bridgestone* MB3-number , any of several Microsoft#Business Division exams...
is likely a dwarf spheroidal galaxy
Dwarf spheroidal galaxy
Dwarf spheroidal galaxy is a term in astronomy applied to low luminosity galaxies that are companions to the Milky Way and to the similar systems that are companions to the Andromeda Galaxy M31...
. Dwingeloo 1 is a member of the IC 342/Maffei Group of galaxies.
Properties
As a barred galaxy Dwingeloo 1 has a central bar and two distinct spiral arms beginning from the ends of the bar at nearly right angle and wound counterclockwise. The length of the arms is up to 180°. The disk of the galaxy is inclined with respect to the observer with the inclination angle being 50°. The galaxy recedes from the Milky Way at the speed of about 256 km/s.The visible radius of Dwingeloo 1 is approximately 4.2′, which at the distance of 3 Mpc corresponds to about 4 kpc. The neutral hydrogen is detected as far as 6 kpc from the center. The total mass of the galaxy within the latter radius is estimated at 25 billion Solar masses. The total mass of the galaxy is about four times that of the Milky Way.
The distribution of the neutral hydrogen in Dwingeloo 1 is typical for barred spiral galaxies—rather flat with a minimum in the center or along the bar. Its total mass is estimated at 370–450 million Solar mass
Solar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es. Dwingeloo 1 is a molecular gas-poor galaxy. The total mass of the molecular hydrogen does not exceed 10% of this value. Optical observations detected around 15 H II region
H II region
An H II region is a large, low-density cloud of partially ionized gas in which star formation has recently taken place. The short-lived, blue stars forged in these regions emit copious amounts of ultraviolet light, ionizing the surrounding gas...
s situated mainly along the spiral arms.