Maffei 1

Maffei 1 is a giant elliptical galaxy in the constellation Cassiopeia. Held once they are a member of the Local Group, the galaxy is part of a private group of galaxies of the Maffei group is now known to be.

It was named after the astronomer Paolo Maffei, who discovered it in 1967 along with its neighboring galaxy Maffei 2 by means of their emission of infrared radiation.

Maffei 1 has a slightly flattened nucleus, a box-like shape and mainly consists of old metal-rich stars. In the inner, small, blue core of the galaxy, however, still do stars. As with all elliptical galaxies Maffei 1 also has a significant number of globular clusters. It is located at a distance of about three to four Megaparsec of our Milky Way. It is therefore likely that our closest giant galaxy.

Maffei 1 is located in the galactic plane of the Milky Way in the so-called Zone of Avoidance, known for the background with a high number of stars and interstellar dust to hide. If we had a clear view of Maffei 1, it would be the largest, with about three quartered diameter of the moon, the brightest and best-known galaxy in the night sky. In the optical field can be observed with telescopes from about 30 centimeters opening with a very dark sky.

Discovery

The Italian astronomer Paolo Maffei was one of the pioneers of infrared astronomy. In the 50s and 60s of the 20th century, he used chemical hyper -sensitized emulsions Eastman IN order to obtain high quality images of celestial objects in the near infrared part of the spectrum (I- band 680-880 nm). [Note 1] In order to achieve this type hypersensitivity, he dipped it for 3 to 5 minutes in a 5% ammonia solution. This procedure increased their sensitivity by an order of magnitude. Between 1957 and 1967, Maffei observed with this technique many different celestial objects, such as Globular clusters and planetary nebulae. Some of these objects were shooting in blue light ( B band 250-500 nm) not visible at all.

The galaxy Maffei 1 was then discovered on a hyper -sensitized IN photographic plate, which was recorded on 29 September 1967, a Schmidt telescope at the Osservatorio di Asiago Astrofisico. Paolo Maffei found Maffei 1, together with their direct neighboring spiral galaxy Maffei 2, while he actually went through the recordings by diffuse nebulae and T Tauri stars. The object had an apparent size of 50 arc seconds on the Nahinfrarotaufnahme, but was not visible to a corresponding receptacle in the Blue.

However, the spectrum had neither emission nor absorption lines. Later it was shown also that they showed almost no activity on the radio range. In 1970, Hyron Spinrad suspected then first that Maffei 1 is a heavily shielded us nearby giant elliptical galaxy.

Maffei 1 would fall below the 10 brightest galaxies in the northern night sky when they would not be covered by our Milky Way.

Due to their faintness in optical images, one needs for visual observation of Maffei 1 is at least a telescope of 30 to 35 inches aperture, hochqualitiative, accurate star maps and a very dark night sky.

Distance

Maffei 1 is removed only 0.55 ° from the galactic plane and is thus in the middle of the so-called Zone of Avoidance. Therefore it is subject to an extinction of 4.7 magnitudes ( a factor of about 1 /70) in the visuals. Add to that the interference by myriads of faint foreground stars of the Milky Way that can be easily confused with the stars of Maffei 1. This makes an accurate distance determination particularly difficult.

1971, soon after their discovery, Hyron Spinrad gauged the distance to about 1 Mpc, which she had placed within the Local Group. In 1983, this estimate of Ronald Buta and McCall Marshall had already been corrected to ( 2.1 ± ) Mpc. They used for this purpose the general relation of brightness to velocity dispersion in elliptical galaxies. This distance placed Maffei 1 clearly outside our Local Group, but to those in the past, quite to have influenced close enough.

1993 used Gerard Luppino and John Tonry obtain the fluctuations of the surface brightness by new estimates of (4.15 ± 0.5 ) Mpc. In 2001, then Tim Davidge and Sidney van den Bergh could with adaptive optics to resolve the brightest individual stars of the asymptotic Riesenasts in Maffei 1 and thus derive a distance of ( 4.4 ± ) Mpc. The most recent determination of the distance is based on a recalibrated brightness velocity dispersion relation for elliptical galaxies and updated extinction and comes to (2.85 ± 0.36 ) Mpc. If all the measurements together to get an average of over a distance of ( 3.32 ± 0.72) Mpc.

The larger distances greater than 3 Mpc, which were derived in the last 20 years, simultaneously mean that Maffei 1 was never close enough to affect significantly the dynamics of the Local Group.

Maffei 1 is removed from our solar system at a speed of about 66 km / s The escape velocity relative to the center of gravity of the Local Group amounted to 297 km / s, a speed corresponding to the distance-dependent value of the expansion of the universe this galaxy.

Properties

Size and shape

Maffei 1 is a giant elliptical galaxy classified as type E3 in the Hubble sequence. This means the galaxy is slightly flattened, the semi-minor axis has 70 % of the length of the semimajor axis. Maffei 1 also light box form (type E ( b) 3 ), whereas the central region ( radius of about 34 pc ) appears somewhat fainter with respect to the r1 / 4 law, [ Note 2 ] which Maffei 1 makes it an elliptical core type galaxy. Both both the Kastenförigkeit as well as the under -luminous core of the galaxy are typical for medium to large elliptical galaxies.

The apparent expansion of Maffei 1 is suspended due to the strong extinction by the Milky Way strongly on the wavelength of the light from. In the blue light it has only one apparent diameter of one to two minutes of arc, while in the near infrared the major axis reaches at least 23 minutes of arc, which corresponds roughly to the three quartered diameter of the moon. At a distance of 3 Mpc, this corresponds to an absolute value of approximately 23 kpc. The absolute visual luminosity of MV = -20.8 m corresponds approximately to that of the Milky Way.

Core

Maffei 1 has a small blue, internal nucleus with a diameter of about 1.2 pc. This contains about 29 M ☉ ionized hydrogen gas. This implies a recently taken place star formation phase. However, there are no signs of an active galactic nucleus in the center of Maffei 1 The X-ray radiation of the core is extended and is probably due to several stellar sources forth.

Stars and star clusters

Maffei 1 is mainly composed of old metal-rich stars with a Aklter of more al 10 billion years. As a large elliptical galaxy Maffei 1 is most likely a large amount of globular clusters (estimated 1100), by the strong absorbance could not however had only be detected with ground-based telescopes.

With the Hubble Space Telescope could be identified in 2000 at least 20 candidates for globular clusters around the central region around. Subsequent infrared observations from ground-based telescopes also found a population of bright globular cluster candidates.

Group membership

Maffei 1 is one of the dominant members of a group are nearby galaxies. The other determining group members are large spiral galaxies such as IC 342 and Maffei 2 Maffei 1 itself also has quite a few satellite galaxies as the smaller spiral galaxy Dwingeloo 1 and a larger number of other dwarf galaxies like MB 1 Maffei Group is one of our Milky Way on the next nearby galaxy groups. Maffei 1 forms with its satellites, a sub-group of Maffei group, the Maffei -1 subgroup.