Messier 47 (M47 or NGC 2422) is an
open cluster in the mildly
southern
Southern may refer to:
Businesses
* China Southern Airlines, airline based in Guangzhou, China
* Southern Airways, defunct US airline
* Southern Air, air cargo transportation company based in Norwalk, Connecticut, US
* Southern Airways Express, M ...
constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object.
The origins of the e ...
of
Puppis
Puppis is a constellation in the southern sky. Puppis, the Latin translation of "poop deck", was originally part of an over-large constellation Argo Navis (the ship of Jason and the Argonauts), which centuries after its initial description, was ...
. It was discovered by
Giovanni Batista Hodierna
Giovanni Battista Hodierna, also spelled as Odierna (April 13, 1597 – April 6, 1660) was an Italian astronomer at the court of Giulio Tomasi, Duke of Palma (Palma di Montechiaro). He compiled a catalogue of comets and other celestial object ...
before 1654 and in his then keynote work re-discovered by
Charles Messier on 1771. It was also independently discovered by
Caroline Herschel.
There is no cluster in the position indicated by Messier, which he expressed in terms of its
right ascension
Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth.
When paired w ...
and
declination
In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...
with respect to the star
2 Puppis. However, if the signs (+ and −) he wrote are swapped, the position matches.
[ Until this equivalency was found, M47 was considered a lost Messier Object. This identification as the same thing (]ad idem
Advertising is the practice and techniques employed to bring attention to a product or service. Advertising aims to put a product or service in the spotlight in hopes of drawing it attention from consumers. It is typically used to promote a ...
) only came in 1959 with a realization by Canadian astronomer T. F. Morris.[
M47 is centered about 1,600 ]light-year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s away and is about 78 million years old. The member star
A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
s have been measured down to about red dwarf
''Red Dwarf'' is a British science fiction comedy franchise created by Rob Grant and Doug Naylor, which primarily consists of a television sitcom that aired on BBC Two between 1988 and 1999, and on Dave since 2009, gaining a cult following. T ...
s at apparent magnitude 19. There are around 500 members,[ the brightest being HD 60855, a magnitude 5.7 Be star. The cluster is dominated by hot class B ]main sequence
In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...
and giant stars, but a noticeable colour contrast comes from its brightest red giant
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
s.[
It about a degree from ]Messier 46
Messier 46 or M46, also known as NGC 2437, is an open cluster of stars in the slightly southern constellation of Puppis. It was discovered by Charles Messier in 1771. Dreyer described it as "very bright, very rich, very large." It is about 5,00 ...
, which is much older and much further away.[
]
Gallery
Eso1441a.jpg, Image of star cluster Messier 47 taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile.
See also
* List of Messier objects
References and footnotes
External links
*
Messier 47, SEDS Messier pages
Amateur Image -
Waid Observatory
'
*
{{Ngc25
Messier 047
Messier 047
047
Messier 047
Orion–Cygnus Arm
?