Maffei 1

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Maffei 1
Maf1atlas.jpg
Observation data (J2000 epoch)
Constellation Cassiopeia
Right ascension 02h 36m 35.4s [1]
Declination +59° 39 19 [1]
Helio radial velocity 66.4 ± 5.0 km/s [2]
Distance 2.85 ± 0.36 Mpc [3]
4.4+0.6
0.5
 Mpc [4]
Apparent magnitude  (V)11.14 ± 0.06 (V-band) [2]
Characteristics
Type S0 pec, [1] E3
Size75,000 ly
(23,000 parsecs)
Apparent size  (V)3.36 × 1.68 [1]
Other designations
PGC 9892, UGCA 034 [1] Sharpless 191

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.

Contents

Maffei 1 is a slightly flattened core type elliptical galaxy. It has a boxy shape and is made mainly of old metal-rich stars. It has a tiny blue nucleus in which stars continue to form. Like all large ellipticals it contains a significant population of globular clusters. Maffei 1 is situated at an estimated distance of 3–4 Mpc from the Milky Way. It may be the closest giant elliptical galaxy.

Maffei 1 lies in the Zone of Avoidance and is heavily obscured by the Milky Way's stars and dust. If it were not obscured, it would be one of the largest (about 3/4 the size of the full moon), brightest, and best-known galaxies in the sky. It can be observed visually, using a 30–35 cm or bigger telescope under a very dark sky.

Discovery

The Italian astronomer Paolo Maffei was one of the pioneers of infrared astronomy. In the 1950s and 60s, in order to obtain high quality images of celestial objects in the very near infrared part of the spectrum (the I-band, 680–880 nm), he used chemically hyper-sensitized standard Eastman emulsions I-N. [note 1] To achieve the hyper-sensitization he immersed them in 5% ammonia solution for 3–5 minutes. This procedure increased their sensitivity by an order of magnitude. Between 1957 and 1967 Maffei observed many different objects using this technique, including globular clusters and planetary nebulae. Some of those objects were not visible at all on blue light (250–500 nm) sensitive plates. [6]

The galaxy Maffei 1 was discovered on a hyper-sensitized I-N photographic plate exposed on 29 September 1967 with the Schmidt telescope at Asiago Observatory. Maffei found Maffei 1, together with its companion spiral galaxy Maffei 2, while searching for diffuse nebulae and T Tauri stars. [2] The object had an apparent size up to 50″ in the near infrared but was not visible on the corresponding blue light sensitive plate. [7] Its spectrum lacked any emission or absorption lines. Later it was shown to be radio-quiet as well. In 1970 Hyron Spinrad suggested that Maffei 1 is a nearby heavily obscured giant elliptical galaxy. [8] Maffei 1 would be among the ten brightest galaxies in the northern sky if not situated behind the Milky Way. [6]

Distance

Maffei 1 is located only 0.55° from the galactic plane in the middle of the zone of avoidance and suffers from about 4.7 magnitudes of extinction (a factor of about 1/70) in visible light. In addition to extinction, observation of Maffei 1 is further hindered by the fact that it is covered by myriads of faint Milky Way stars, which can easily be confused with its own. As a result, determining its distance has been particularly difficult. [2]

In 1971, soon after its discovery, Hyron Spinrad estimated the distance to Maffei 1 at about 1 Mpc, which would place it within the Local Group of galaxies. In 1983 this estimate was revised up to 2.1+1.3
0.8
 Mpc by Ronald Buta and Marshall McCall using the general relation between the luminosity and velocity dispersion for elliptical galaxies. [2] That distance puts Maffei 1 well outside the Local Group, but close enough to have influenced it in the past. [4]

In 1993 Gerard Luppino and John Tonry used surface brightness fluctuations to derive a new distance estimate to Maffei 1 of 4.15 ± 0.5 Mpc. Later in 2001, Tim Davidge and Sidney van den Bergh used adaptive optics to observe the brightest asymptotic giant branch stars in Maffei 1 and concluded that it is located at the distance 4.4+0.6
0.5
 Mpc from the Sun. [4] [2] The latest determination of the distance to Maffei 1, which is based on the re-calibrated luminosity/velocity dispersion relation for the elliptical galaxies and the updated extinction, is 2.85 ± 0.36 Mpc, or over 9 million light years away. For perspective, the nearby Andromeda Galaxy is estimated to be about 2.5 million light years away.

The larger (≥3 Mpc) distances reported in the past 20 years would imply that Maffei 1 has never been close enough to the Local Group to significantly influence its dynamics. [3]

Maffei 1 moves away from the Sun at the speed of about 66 km/s. [2] Its velocity relative to the Local Group's center of mass is, however, 297 km/s away. That means that Maffei 1 participates in the general expansion of the Universe. [9]

Physical properties

Size and shape

The surface brightness profile of Maffei 1 in the blue (B-band) and near infrared (I-band) light Maffei 1 surface brightness.png
The surface brightness profile of Maffei 1 in the blue (B-band) and near infrared (I-band) light

Maffei 1 is a massive elliptical galaxy classified as type E3 in the Hubble classification scheme. [10] This means that it is slightly flattened, its semi-minor axis being 70% of its semi-major axis. Maffei 1 has also a boxy shape (E(b)3 type), while its central region (radius ≈ 34 pc) is deficient in light emission as compared to the r1/4 law, [note 2] meaning that Maffei 1 is a core type elliptical. Both the boxy shape and the presence of an underluminous core are typical of intermediate to massive ellipticals. [11]

The apparent dimensions of Maffei 1 depend strongly on the wavelength of light because of the heavy obscuration by the Milky Way. In blue light it is 1–2′ across while in the near infrared its major axis reaches 23′—more than 3/4 of the Moon's diameter. At a distance of 3 Mpc this corresponds to approximately 23 kpc. [10] The total visible absolute magnitude of Maffei 1, MV=−20.8, is comparable to that of the Milky Way. [3]

Maffei 1 is the bluish elliptical object near the bottom-right corner. Maffei 1 and 2 cropped.jpg
Maffei 1 is the bluish elliptical object near the bottom-right corner.

Nucleus

Maffei 1 possesses a tiny blue nucleus at its center approximately 1.2 pc across. It contains about 29 solar masses of ionized hydrogen. [11] This implies that it has undergone recent star formation. There are no signs of an active galactic nucleus (AGN) in the center of Maffei 1. The X-ray emission from the center is extended and likely comes from a number of stellar sources. [12]

Stars and stellar clusters

Maffei 1 is mainly made of old metal-rich stars more than 10 billion years in age. [12] As a large elliptical galaxy, Maffei 1 is expected to host a significant population of globular clusters (about 1100). However, due to heavy intervening absorption, ground-based observations for a long time failed to identify any of them. [12] Observations by the Hubble Space Telescope in 2000 revealed about 20 globular cluster candidates in the central region of the galaxy. [11] Later infrared observations from telescopes on the ground also found a population of bright globular cluster candidates. [13]

Group membership

Maffei 1 is a principal member of a nearby group of galaxies. The group's other members are the giant spiral galaxies IC 342 and Maffei 2. Maffei 1 has also a small satellite spiral galaxy, Dwingeloo 1, as well as a number of dwarf satellites like MB1. The IC 342/Maffei Group is one of the closest galaxy groups to the Milky Way galaxy. [9]

Notes

  1. "Eastman emulsions I-N" refers to a type of photographic plate produced by Eastman Kodak in the 20th century. They were sensitive in the very near part of the infrared spectrum and at that time widely used for astronomical observations. However they required long exposure times and were often hyper-sensitized. [5]
  2. The r1/4 law refers to an empirical relation describing how the surface brightness of an elliptical galaxy varies along its radius. It takes the following form: , where r is radius, μ is the surface brightness (in mag/arsec2), while A and B are empirical constants. [10]

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<span class="mw-page-title-main">Globular cluster</span> Spherical collection of stars

A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of member stars. Their name is derived from Latin globulus. Globular clusters are occasionally known simply as "globulars".

<span class="mw-page-title-main">Local Group</span> Group of galaxies that includes the Milky Way

The Local Group is the galaxy group that includes the Milky Way. 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">Andromeda Galaxy</span> Barred spiral galaxy in the Local Group

The Andromeda Galaxy, also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about 46.56 kiloparsecs approximately 765 kpc from Earth and the nearest large galaxy to the Milky Way. The galaxy's name stems from the area of Earth's sky in which it appears, the constellation of Andromeda, which itself is named after the princess who was the wife of Perseus in Greek mythology.

<span class="mw-page-title-main">Virgo Cluster</span> Galaxy cluster in the constellation Virgo

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<span class="mw-page-title-main">Messier 87</span> Elliptical galaxy in the Virgo Galaxy Cluster

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters — about 15,000 compared with the 150–200 orbiting the Milky Way — and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.

<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.

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.

<span class="mw-page-title-main">Messier 81</span> Grand design spiral galaxy in the constellation Ursa Major

Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a grand design spiral galaxy about 12 million light-years away in the constellation Ursa Major. It has a D25 isophotal diameter of 29.44 kiloparsecs (96,000 light-years). Because of its relative proximity to the Milky Way galaxy, large size, and active galactic nucleus (which harbors a 70 million M supermassive black hole), Messier 81 has been studied extensively by professional astronomers. The galaxy's large size and relatively high brightness also makes it a popular target for amateur astronomers. In late February 2022, astronomers reported that M81 may be the source of FRB 20200120E, a repeating fast radio burst.

<span class="mw-page-title-main">Sombrero Galaxy</span> Peculiar galaxy in the constellation Virgo

The Sombrero Galaxy is a peculiar galaxy of unclear classification in the constellation borders of Virgo and Corvus, being about 9.55 megaparsecs from the Milky Way galaxy. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It has a diameter of approximately 15 kiloparsecs, three-tenths the size of the Milky Way.

<span class="mw-page-title-main">Messier 86</span> Elliptical galaxy in the constellation Virgo

Messier 86 is an elliptical or lenticular galaxy in the constellation Virgo. It was discovered by Charles Messier in 1781. M86 lies in the heart of the Virgo Cluster of galaxies and forms a most conspicuous group with another large galaxy known as Messier 84. It displays the highest blue shift of all Messier objects, as it is, net of its other vectors of travel, approaching the Milky Way at 244 km/s. This is due to both galaxies falling roughly towards the center of the Virgo cluster from opposing ends.

<span class="mw-page-title-main">NGC 1569</span> Dwarf irregular galaxy in the constellation Camelopardalis

NGC 1569 is a dwarf irregular galaxy in Camelopardalis. The galaxy is relatively nearby and consequently, the Hubble Space Telescope can easily resolve the stars within the galaxy. The distance to the galaxy was previously believed to be only 2.4 Mpc. However, in 2008 scientists studying images from Hubble calculated the galaxy's distance at nearly 11 million light-years away, about 4 million light-years farther than previous thought, meaning it is a member of the IC 342 group of galaxies.

<span class="mw-page-title-main">NGC 1316</span> Lenticular radio galaxy in the constellation Fornax

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<span class="mw-page-title-main">Dorado Group</span> Galaxy cluster in the constellation Dorado

The Dorado Group is a loose concentration of galaxies containing both spirals and ellipticals. It is generally considered a 'galaxy group' but may approach the size of a 'galaxy cluster'. It lies primarily in the southern constellation Dorado and is one of the richest galaxy groups of the Southern Hemisphere. Gérard de Vaucouleurs was the first to identify it in 1975 as a large complex nebulae II in the Dorado region, designating it as G16.

<span class="mw-page-title-main">NGC 1404</span> Elliptical galaxy in the Fornax Cluster

NGC 1404 is an elliptical galaxy in the Southern constellation Eridanus. It was discovered on November 28, 1837, by the astronomer John Herschel. Based on the tip of the red-giant branch distance indicator, it lies at a distance of approximately 60 million light-years from the Milky Way. It is one of the brightest members of the Fornax Cluster.

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. MB 3 is thought to be a member of the IC 342/Maffei Group, a galaxy group adjacent to the Local Group.

<span class="mw-page-title-main">NGC 4636</span> Elliptical galaxy in the constellation Virgo

NGC 4636 is an elliptical galaxy located in the constellation Virgo. It is a member of the NGC 4753 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It is located at a distance of about 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4636 is about 105,000 light years across.

<span class="mw-page-title-main">NGC 5846</span> Elliptical galaxy in the constellation Virgo

NGC 5846 is an elliptical galaxy located in the constellation Virgo. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 5846 is about 110,000 light years across. It was discovered by William Herschel on February 24, 1786. It lies near 110 Virginis and is part of the Herschel 400 Catalogue. It is a member of the NGC 5846 Group of galaxies, itself one of the Virgo III Groups strung out to the east of the Virgo Supercluster of galaxies.

<span class="mw-page-title-main">IC 1459</span> Elliptical galaxy in the constellation of Grus

IC 1459 is an elliptical galaxy located in the constellation Grus. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that IC 1459 is about 130,000 light-years across. It was discovered by Edward Emerson Barnard in 1892.

<span class="mw-page-title-main">NGC 1549</span> Elliptical galaxy in the constellation Dorado

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References

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  12. 1 2 3 Davidge, T. J. (2002). "The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128". The Astronomical Journal. 124 (4): 2012–2022. arXiv: astro-ph/0207122 . Bibcode:2002AJ....124.2012D. doi:10.1086/342535. S2CID   17850497.
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