View source for Astronomy:Maffei 1

{{short description|Galaxy in the constellation Cassiopeia}}
{{Infobox galaxy
| name = Maffei 1
| image = Maf1atlas.jpg
| image_size = 275px
| epoch = [[Astronomy:Epoch#Julian years and J2000|J2000]]
| type = S0<sup>−</sup> pec,<ref name="ned"/> E3
| ra = {{RA|02|36|35.4}}<ref name="ned" />
| dec = {{DEC|+59|39|19}}<ref name="ned" />
| dist_ly = {{nowrap|2.85 ± 0.36 [[Astronomy:Parsec|Mpc]]}}<ref name=Fingerhut2007/><br>4.4{{±|0.6|0.5}}&nbsp;Mpc<ref name=Davidge2001/>
| h_radial_v = {{nowrap|66.4 ± 5.0 km/s}}<ref name=Fingerhut2003/>
| appmag_v = {{nowrap|11.14 ± 0.06}} (V-band)<ref name=Fingerhut2003/>
| size_v = 3&prime;.36 &times; 1&prime;.68<ref name="ned" />
| size = 75,000 [[Astronomy:Light-year|ly]] <br>(23,000 [[Astronomy:Parsec|parsec]]s)
| constellation name = [[Astronomy:Cassiopeia (constellation)|Cassiopeia]]
| names = [[Astronomy:Principal Galaxies Catalogue|PGC]] 9892, [[Astronomy:Uppsala General Catalogue Addendum|UGCA]] 034<ref name="ned" /> [[Astronomy:Sharpless catalog|Sharpless]] 191
}}

'''Maffei 1''' is a massive [[Astronomy:Elliptical galaxy|elliptical galaxy]] in the [[Astronomy:Constellation|constellation]] [[Astronomy:Cassiopeia (constellation)|Cassiopeia]]. Once believed to be a member of the [[Astronomy:Local Group|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 [[Astronomy:Maffei 2|Maffei 2]] in 1967 via their [[Physics:Infrared|infrared]] emissions.

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&nbsp;Mpc from the Milky Way. It may be the closest giant elliptical galaxy.

Maffei 1 lies in the [[Astronomy:Zone of Avoidance|Zone of Avoidance]] and is heavily obscured by the Milky Way's [[Astronomy:Star|star]]s and [[Astronomy:Cosmic dust|dust]]. If it were not obscured, it would be one of the largest (about {{frac|3|4}} the size of the [[Astronomy:Full moon|full moon]]), brightest, and best-known galaxies in the sky. It can be observed visually, using a 30–35&nbsp;cm or bigger telescope under a very dark sky.

==Discovery==
The Italian astronomer Paolo Maffei was one of the pioneers of [[Astronomy:Infrared astronomy|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&nbsp;nm), he used chemically hyper-sensitized standard Eastman emulsions I-N.{{refn|"Eastman emulsions I-N" refers to a type of [[Physics:Photographic plate|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.<ref name=Snaduleak1961/>|group=note}} To achieve the hyper-sensitization he immersed them in 5% [[Chemistry:Ammonia|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&nbsp;nm) sensitive plates.<ref name=Maffei2003/>

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 [[Astronomy:Maffei 2|Maffei 2]], while searching for diffuse nebulae and [[Astronomy:T Tauri star|T Tauri star]]s.<ref name=Fingerhut2003/> The object had an apparent size up to 50″ in the near infrared but was not visible on the corresponding blue light sensitive plate.<ref name=Maffei1968/> 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.<ref name=Bell1970/> Maffei 1 would be among the ten brightest galaxies in the northern sky if not situated behind the Milky Way.<ref name=Maffei2003/>

==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 [[Astronomy:Extinction|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.<ref name=Fingerhut2003/>

In 1971, soon after its discovery, Hyron Spinrad estimated the distance to Maffei 1 at about 1&nbsp;Mpc, which would place it within the [[Astronomy:Local Group|Local Group]] of galaxies. In 1983 this estimate was revised up to 2.1{{±|1.3|0.8}}&nbsp;Mpc by Ronald Buta and Marshall McCall using the general relation between the luminosity and [[Astronomy:Velocity dispersion|velocity dispersion]] for elliptical galaxies.<ref name=Fingerhut2003/> That distance puts Maffei 1 well outside the Local Group, but close enough to have influenced it in the past.<ref name=Davidge2001/>

In 1993 Gerard Luppino and John Tonry used surface brightness fluctuations to derive a new distance estimate to Maffei 1 of {{nowrap|4.15 ± 0.5 Mpc}}. Later in 2001, Tim Davidge and Sidney van den Bergh used adaptive optics to observe the brightest [[Astronomy:Asymptotic giant branch|asymptotic giant branch]] stars in Maffei 1 and concluded that it is located at the distance 4.4{{±|0.6|0.5}}&nbsp;Mpc from the [[Astronomy:Sun|Sun]].<ref name=Davidge2001/><ref name=Fingerhut2003/> 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 {{nowrap|2.85 ± 0.36 Mpc}}, or over 9 million light years away. For perspective, the nearby [[Astronomy:Andromeda Galaxy|Andromeda Galaxy]] is estimated to be about 2.5 million light years away.

The larger (≥3&nbsp;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.<ref name=Fingerhut2007/>

Maffei 1 moves away from the Sun at the speed of about 66&nbsp;km/s.<ref name=Fingerhut2003/> Its velocity relative to the Local Group's [[Physics:Center of mass|center of mass]] is, however, 297&nbsp;km/s away. That means that Maffei 1 participates in the general expansion of the Universe.<ref name=Karachentsev2003/>

==Physical properties==

===Size and shape===
[[File:Maffei 1 surface brightness.png|thumb|The surface brightness profile of Maffei 1 in the blue (B-band) and near infrared (I-band) light<ref name=Buta1999/>]]
Maffei 1 is a massive elliptical galaxy classified as type E3 in the Hubble classification scheme.<ref name=Buta1999/> 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&nbsp;pc) is deficient in light emission as compared to the r<sup>1/4</sup> law,{{refn|The r<sup>1/4</sup> law refers to an empirical relation describing how the surface brightness of an elliptical galaxy varies along its radius. It takes the following form: <math>\mu=A+Br^{1/4}</math>, where ''r'' is radius, ''&mu;'' is the surface brightness (in mag/arsec<sup>2</sup>), while ''A'' and ''B'' are empirical constants.<ref name=Buta1999/>|group=note}} 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.<ref name=Buta2003/>

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&nbsp;Mpc this corresponds to approximately 23&nbsp;kpc.<ref name=Buta1999/> The total visible absolute magnitude of Maffei 1, M<sub>V</sub>=−20.8, is comparable to that of the Milky Way.<ref name=Fingerhut2007/>

[[File:Maffei 1 and 2 cropped.jpg|thumb|left|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&nbsp;pc across. It contains about 29 [[Astronomy:Solar mass|solar mass]]es of ionized hydrogen.<ref name=Buta2003/> This implies that it has undergone recent star formation. There are no signs of an [[Active galactic nucleus|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.<ref name=Davidge2002/>

===Stars and stellar clusters===
Maffei 1 is mainly made of old metal-rich stars more than 10 billion years in age.<ref name=Davidge2002/> As a large elliptical galaxy, Maffei 1 is expected to host a significant population of [[Astronomy:Globular cluster|globular cluster]]s (about 1100). However, due to heavy intervening absorption, ground-based observations for a long time failed to identify any of them.<ref name=Davidge2002/> Observations by the [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]] in 2000 revealed about 20 globular cluster candidates in the central region of the galaxy.<ref name=Buta2003/> Later infrared observations from telescopes on the ground also found a population of bright globular cluster candidates.<ref name=Davidge2005/>

==Group membership==
Maffei 1 is a principal member of a nearby group of galaxies. The group's other members are the giant spiral galaxies [[Astronomy:IC 342|IC 342]] and [[Astronomy:Maffei 2|Maffei 2]]. Maffei 1 has also a small satellite spiral galaxy, [[Astronomy:Dwingeloo 1|Dwingeloo 1]], as well as a number of dwarf satellites like MB1. The {{nowrap|IC 342/Maffei}} Group is one of the closest galaxy groups to the Milky Way galaxy.<ref name=Karachentsev2003/>{{clear}}

==Notes==
{{reflist|group=note}}

==References==
{{Reflist|30em|refs=
<ref name=Karachentsev2003>{{Cite journal | last1 = Karachentsev | first1 = I. D. | last2 = Sharina | first2 = M. E. | last3 = Dolphin | first3 = A. E. | last4 = Grebel | first4 = E. K. | title = Distances to nearby galaxies around IC 342 | doi = 10.1051/0004-6361:20030912 | journal = Astronomy and Astrophysics | volume = 408 | pages = 111–118 | year = 2003 |bibcode = 2003A&A...408..111K | doi-access = free }}</ref>
<ref name=Fingerhut2003>{{Cite journal | last1 = Fingerhut | first1 = R. L. | last2 = McCall | first2 = M. L. | last3 = De Robertis | first3 = M. | last4 = Kingsburgh | first4 = R. L. | last5 = Komljenovic | first5 = M. | last6 = Lee | first6 = H. | last7 = Buta | first7 = R. J. | doi = 10.1086/368339 | title = The Extinction and Distance of Maffei 1 | journal = The Astrophysical Journal | volume = 587 | issue = 2 | pages = 672–684 | year = 2003 |arxiv = astro-ph/0301414 |bibcode = 2003ApJ...587..672F | s2cid = 14863189 }}</ref>
<ref name=Fingerhut2007>{{Cite journal | last1 = Fingerhut | first1 = R. L. | last2 = Lee | first2 = H. | last3 = McCall | first3 = M. L. | last4 = Richer | first4 = M. G. | title = The Extinction and Distance of Maffei 2 and a New View of the IC 342/Maffei Group | doi = 10.1086/509862 | journal = The Astrophysical Journal | volume = 655 | issue = 2 | pages = 814–830 | year = 2007 |arxiv = astro-ph/0610044 |bibcode = 2007ApJ...655..814F | s2cid = 18405597 }}</ref>
<ref name=Davidge2001>{{Cite journal | last1 = Davidge | first1 = T. J. | last2 = Van Den Bergh | first2 = S. | doi = 10.1086/320692 | title = The Detection of Bright Asymptotic Giant Branch Stars in the Nearby Elliptical Galaxy Maffei 1 | journal = The Astrophysical Journal | volume = 553 | issue = 2 | pages = L133 | year = 2001 |arxiv = astro-ph/0104436 |bibcode = 2001ApJ...553L.133D | s2cid = 16512319 }}</ref>
<ref name="ned">{{cite web
  | title=NASA/IPAC Extragalactic Database
  | work=Results for Maffei 1
  | url=http://nedwww.ipac.caltech.edu/cgi-bin/nph-objsearch?objname=Maffei+1&img_stamp=yes&extend=no
  | access-date=2006-11-18 }}</ref>
<ref name=Buta2003>{{Cite journal | last1 = Buta | first1 = R. | last2 = McCall | first2 = M. L. | doi = 10.1086/367789 | title = Maffei 1 with the Hubble Space Telescope| journal = The Astronomical Journal | volume = 125 | issue = 3 | pages = 1150 | year = 2003 |bibcode = 2003AJ....125.1150B | s2cid = 118394917 | doi-access = free }}</ref>
<ref name=Buta1999>{{Cite journal | last1 = Buta | first1 = R. J. | last2 = McCall | first2 = M. L. | doi = 10.1086/313255 | title = The IC 342/Maffei Group Revealed | journal = The Astrophysical Journal Supplement Series | volume = 124 | issue = 1 | pages = 33–93 | year = 1999 |bibcode = 1999ApJS..124...33B | s2cid = 119907629 | doi-access = free }}</ref>
<ref name=Davidge2002>{{Cite journal | last1 = Davidge | first1 = T. J. | title = The Upper Asymptotic Giant Branch of the Elliptical Galaxy Maffei 1 and Comparisons with M32 and NGC 5128 | doi = 10.1086/342535 | journal = The Astronomical Journal | volume = 124 | issue = 4 | pages = 2012–2022 | year = 2002 |arxiv = astro-ph/0207122 |bibcode = 2002AJ....124.2012D | s2cid = 17850497 }}</ref>
<ref name=Davidge2005>{{Cite journal | last1 = Davidge | first1 = T. J. | last2 = Van Den Bergh | first2 = S. | doi = 10.1086/430367 | title = The Globular Cluster Content of Maffei 1 | journal = Publications of the Astronomical Society of the Pacific | volume = 117 | issue = 832 | pages = 589 | year = 2005 |arxiv = astro-ph/0504335 |bibcode = 2005PASP..117..589D | s2cid = 119059616 }}</ref>
<ref name=Bell1970>{{Cite journal | last1 = Bell | first1 = M. B. | last2 = Seaquist | first2 = E. R. | last3 = Braun | first3 = L. D. | title = Nonthermal Radio Emission from an Infrared Object in the Region of IC 1805 | doi = 10.1086/180561 | journal = The Astrophysical Journal | volume = 161 | pages = L13 | year = 1970 |bibcode = 1970ApJ...161L..13B | doi-access = free }}</ref>
<ref name=Maffei1968>{{Cite journal | last1 = Maffei | first1 = P. | doi = 10.1086/128698 | title = Infrared Object in the Region of IC 1895 | journal = Publications of the Astronomical Society of the Pacific | volume = 80 | issue = 476 | pages = 618 | year = 1968 |bibcode = 1968PASP...80..618M | doi-access = free }}</ref>
<ref name=Maffei2003>{{cite journal|last=Maffei|first=Paolo|title=My researches at the infrared doors|journal=Memorie della Società Astronomica Italiana|volume=74|pages=19–28|date=2003|bibcode = 2003MmSAI..74...19M }}</ref>
<ref name=Snaduleak1961>{{cite journal|last=Sanduleak|first=N.|title=Hypersentivisation Gains in the Near Infrared|journal=The Astronomical Journal|volume=66|pages=526–8|date=1961|doi=10.1086/108456|bibcode = 1961AJ.....66..526S |url=http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1961AJ.....66R..53S&link_type=ARTICLE&db_key=AST&high=|doi-access=free}}
</ref>
<!--unused<ref name=Trusock2005>{{cite journal|url=http://www.cloudynights.com/documents/SWCass.pdf|title=Small Wonders: Cassiopeia|author=Trusock, Tom|date=6 November 2005|journal=Cloudy Nights Telescope Reviews|publisher=cloudynights.com|format=pdf}}</ref>-->
}}

==External links==
* [http://www.astr.ua.edu/gifimages/maffei1.html Maffei 1]
* {{WikiSky|z=9}}
*[http://apod.nasa.gov/apod/ap100309.html Galaxies Beyond the Heart: Maffei 1 and 2]—Astronomy Picture of the Day 2010 March 9


{{Sky|02|36|35.4|+|59|39|19|9800000}}

[[Category:Elliptical galaxies]]
[[Category:Peculiar galaxies]]
[[Category:Cassiopeia (constellation)]]
[[Category:Principal Galaxies Catalogue objects|09892]]
[[Category:Sharpless objects]]
[[Category:UGCA objects]]

{{Sourceattribution|Maffei 1}}