Butterfly Cluster

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Butterfly Cluster
Messier 6 - The Butterfly Cluster.jpg
Observation data (J2000.0 epoch)
Right ascension 17h 40.1m [1]
Declination −32° 13′ [1]
Distance 1.59  kly (0.487  kpc) [1]
Apparent magnitude  (V)4.2 [2]
Apparent dimensions (V)25′ [2]
Physical characteristics
Radius6 [3] light-years
Estimated age94.2 [1]  Myr
Other designationsMessier 6, NGC 6405, Cr 341, Mel 178, Lund 769, OCL 1030, [4] ESO 455-SC030
Associations
Constellation Scorpius
See also: Open cluster, List of open clusters

The Butterfly Cluster (cataloged as Messier 6 or M6, and as NGC 6405) is an open cluster of stars in the southern constellation of Scorpius. Its name derives from the vague resemblance of its shape to a butterfly. [5] The Trumpler classification of II 3 r [6] encodes it is rich in stars, ranks II out of IV for disparateness and greatly mixes bright with faint components. It is 3.5° to the northwest of Messier 7, both north of the tail of Scorpius. [7]

Contents

The first astronomer to record the Butterfly Cluster's existence was Giovanni Battista Hodierna in 1654. However, Robert Burnham Jr. has proposed that the 2nd century astronomer Ptolemy may have seen it with the naked eye while observing its neighbor the Ptolemy Cluster (M7). [7] Credit for the discovery is usually given to Jean-Philippe Loys de Chéseaux in 1746. Charles Messier observed the cluster on May 23, 1764, and added it to his Messier Catalog. [5]

Estimates of the Butterfly Cluster's distance have varied over the years. [8] Wu et al. (2009) found a distance estimate of 1,590 light-years, [1] giving it a spatial dimension of some 12 light years. [3] Modern measurements show its total visual brightness to be magnitude 4.2. The cluster is estimated to be 94.2 [1]  million years old. Cluster members show a slightly higher abundance of elements heavier than helium compared to the Sun; [9] what astronomers refer to as the metallicity.

120 stars, ranging down to visual magnitude 15.1, have been identified as most likely cluster members. [8] Most of the bright stars in this cluster are hot, blue B-type stars but the brightest member is a K-type orange giant star, BM Scorpii, [10] which contrasts sharply with its blue neighbours in photographs. BM Scorpii, is classed as a semiregular variable star, its brightness varying from magnitude +5.5 to magnitude +7.0. There are also eight candidate chemically peculiar stars. [6] [8]

The cluster is located 24.59 ± 0.13 kly (7.54 ± 0.04 kpc) [9] from the Galactic Center and is following an orbit through the Milky Way galaxy with a low eccentricity of 0.03 and an orbital period of 204.2 Myr. At present it is 23 ly (7 pc) below the galactic plane, and it will cross the plane every 29.4 Myr. [1]

As of January 2022, the Butterfly Cluster is one of the few remaining objects within the Messier Catalog to not have been photographed by the Hubble Space Telescope. [11]

See also

Related Research Articles

<span class="mw-page-title-main">Scorpius</span> Zodiac constellation in the southern celestial hemisphere

Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation that pre-dates the Greeks; it is one of the 48 constellations identified by the Greek astronomer Ptolemy in the second century. Its old astronomical symbol is (♏︎).

<span class="mw-page-title-main">Messier 4</span> Globular cluster in Scorpius

Messier 4 or M4 is a globular cluster in the constellation of Scorpius. It was discovered by Philippe Loys de Chéseaux in 1745 and catalogued by Charles Messier in 1764. It was the first globular cluster in which individual stars were resolved.

<span class="mw-page-title-main">Messier 72</span> Globular cluster in the constellation Aquarius

Messier 72 is a globular cluster in the south west of the very mildly southern constellation of Aquarius.

<span class="mw-page-title-main">Messier 80</span> Globular cluster in the constellation Scorpius

Messier 80 is a globular cluster in the constellation Scorpius. It was discovered by Charles Messier in 1781, being one of his first discoveries.

<span class="mw-page-title-main">Messier 10</span> Globular cluster in the constellation Ophiuchus

Messier 10 or M10 is a globular cluster of stars in the equatorial constellation of Ophiuchus. The object was discovered by the French astronomer Charles Messier on May 29, 1764, who cataloged it as number 10 in his catalogue and described it as a "nebula without stars". In 1774, German astronomer Johann Elert Bode likewise called it a "nebulous patch without stars; very pale". Using larger instrumentation, German-born astronomer William Herschel was able to resolve the cluster into its individual members. He described it as a "beautiful cluster of extremely compressed stars". William Parsons, 3rd Earl of Rosse thought he could distinguish a dark lane through part of the cluster. The first to estimate the distance to the cluster was Harlow Shapley, although his derivation of 33,000 light years was much further than the modern value.

<span class="mw-page-title-main">Messier 21</span> Open cluster in the constellation Sagittarius

Messier 21 or M21, also designated NGC 6531 or Webb's Cross, is an open cluster of stars located to the north-east of Sagittarius in the night sky, close to the Messier objects M20 to M25. It was discovered and catalogued by Charles Messier on June 5, 1764. This cluster is relatively young and tightly packed. A few blue giant stars have been identified in the cluster, but Messier 21 is composed mainly of small dim stars. With a magnitude of 6.5, M21 is not visible to the naked eye; however, with the smallest binoculars it can be easily spotted on a dark night. The cluster is positioned near the Trifid nebula, but is not associated with that nebulosity. It forms part of the Sagittarius OB1 association.

<span class="mw-page-title-main">Messier 26</span> Open cluster in the constellation Scutum

Messier 26, also known as NGC 6694, is an open cluster of stars in the southern constellation of Scutum. It was discovered by Charles Messier in 1764. This 8th magnitude cluster is a challenge to find in ideal skies with typical binoculars, where it can be, with any modern minimum 3-inch (76 mm) aperture device. It is south-southwest of the open cluster Messier 11 and is 14′ across. About 25 stars are visible in a telescope with a 150–200 mm (6–8 in) aperture.

<span class="mw-page-title-main">Messier 28</span> Globular cluster in the constellation of Sagittarius

Messier 28 or M28, also known as NGC 6626, is a globular cluster of stars in the center-west of Sagittarius. It was discovered by French astronomer Charles Messier in 1764. He briefly described it as a "nebula containing no star... round, seen with difficulty in 31⁄2-foot telescope; Diam 2′."

<span class="mw-page-title-main">Messier 36</span> Open cluster in the constellation Auriga

Messier 36 or M36, also known as NGC 1960, is an open cluster of stars in the somewhat northern Auriga constellation. It was discovered by Giovanni Batista Hodierna before 1654, who described it as a nebulous patch. The cluster was independently re-discovered by Guillaume Le Gentil in 1749, then Charles Messier observed it in 1764 and added it to his catalogue. It is about 1,330 pc away from Earth. The cluster is very similar to the Pleiades cluster (M45), and if as far away it would be of similar apparent magnitude.

<span class="mw-page-title-main">Messier 37</span> Open cluster in the constellation Auriga

Messier 37 is the brightest and richest open cluster in the constellation Auriga. It was discovered by the Italian astronomer Giovanni Battista Hodierna before 1654. M37 was missed by French astronomer Guillaume Le Gentil when he rediscovered M36 and M38 in 1749. French astronomer Charles Messier independently rediscovered M37 in September 1764 but all three of these clusters were recorded by Hodierna. It is classified as Trumpler type I,1,r or I,2,r.

<span class="mw-page-title-main">Messier 39</span> Open cluster in the constellation Cygnus

Messier 39 or M39, also known as NGC 7092, is an open cluster of stars in the constellation of Cygnus, positioned two degrees to the south of the star Pi Cygni and around 9° east-northeast of Deneb. The cluster was discovered by Guillaume Le Gentil in 1749, then Charles Messier added it to his catalogue in 1764. When observed in a small telescope at low power the cluster shows around two dozen members but is best observed with binoculars. It has a total integrated magnitude (brightness) of 5.5 and spans an angular diameter of 29 arcminutes – about the size of the full Moon. It is centered about 1,010 light-years away.

<span class="mw-page-title-main">Messier 46</span> Open cluster in the constellation Puppis

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 5,000 light-years away. There are an estimated 500 stars in the cluster with a combined mass of 453 M☉, and it is thought to be a mid-range estimate of 251.2 million years old.

<span class="mw-page-title-main">Messier 48</span> Open cluster in the constellation Hydra

Messier 48 or M48, also known as NGC 2548, is an open cluster of stars in the equatorial constellation of Hydra. It sits near Hydra's westernmost limit with Monoceros, about 18° 34′ to the east and slightly south of Hydra's brightest star, Alphard. This grouping was discovered by Charles Messier in 1771, but there is no cluster precisely where Messier indicated; he made an error, as he did with M47. The value that he gave for the right ascension matches, however, his declination is off by five degrees. Credit for discovery is sometimes given instead to Caroline Herschel in 1783. Her nephew John Herschel described it as, "a superb cluster which fills the whole field; stars of 9th and 10th to the 13th magnitude – and none below, but the whole ground of the sky on which it stands is singularly dotted over with infinitely minute points".

<span class="mw-page-title-main">Messier 52</span> Open cluster in the constellation Cassiopeia

Messier 52 or M52, also known as NGC 7654, is an open cluster of stars in the highly northern constellation of Cassiopeia. It was discovered by Charles Messier in 1774. It can be seen from Earth under a good night sky with binoculars. The brightness of the cluster is influenced by extinction, which is stronger in the southern half. Its metallicity is somewhat below that of the Sun, and is estimated to be [Fe/H] = −0.05 ± 0.01.

<span class="mw-page-title-main">Messier 79</span> Globular cluster in constellation Lepus

Messier 79 is a globular cluster in the southern constellation Lepus. It was discovered by Pierre Méchain in 1780 and is about 42,000 light-years away from Earth and 60,000 light years from the Galactic Center.

<span class="mw-page-title-main">Messier 93</span> Open cluster in the constellation Puppis

Messier 93 or M93, also known as NGC 2447, is an open cluster in the modestly southern constellation Puppis, the imagined poop deck of the legendary Argo.

<span class="mw-page-title-main">Lambda Scorpii</span> Triple star system in the constellation Scorpius

Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named Shaula; Lambda Scorpii is its Bayer designation, which is Latinised from λ Scorpii and abbreviated Lambda Sco or λ Sco. With an apparent visual magnitude of 1.62, it is one of the brightest stars in the night sky.

<span class="mw-page-title-main">G Scorpii</span> Star in the constellation Scorpius

G Scorpii, also named Fuyue, is a giant star in the constellation of Scorpius. It has an apparent magnitude of +3.19. It is approximately 126 light-years from the Sun.

<span class="mw-page-title-main">NGC 6231</span> Open Cluster in the constellation of Scorpius

NGC 6231 is an open cluster in the southern sky located half a degrees north of Zeta Scorpii. NGC 6231 is part of a swath of young, bluish stars in the constellation Scorpius known as the Scorpius OB1 association. The star Zeta1 is a member of this association, while its brighter apparent partner, Zeta2, is only 150 ly from Earth and so is not a member.

<span class="mw-page-title-main">NGC 6281</span> Open cluster in the constellation of Scorpius

NGC 6281 is an open cluster of stars in the constellation Scorpius. It was not included in the Messier or Caldwell catalogues of nebulous objects, but it is the brightest such cluster in the constellation to be left out of both. It is readily observed with the naked eye; it is located about 2° to the east of Mu Scorpii. James Dunlop described the cluster as a "curiously curved line of pretty bright stars, with many stars mixt". John Herschel then described the cluster as both "pretty bright" and "pretty rich".

References

  1. 1 2 3 4 5 6 7 Wu, Zhen-Yu; et al. (November 2009), "The orbits of open clusters in the Galaxy", Monthly Notices of the Royal Astronomical Society , 399 (4): 2146–2164, arXiv: 0909.3737 , Bibcode:2009MNRAS.399.2146W, doi:10.1111/j.1365-2966.2009.15416.x, S2CID   6066790.
  2. 1 2 Frommert, Hartmut; Kronberg, Christine (August 21, 2007), "Messier 6", SEDS Messier pages, Students for the Exploration and Development of Space (SEDS), retrieved 2018-12-07.
  3. 1 2 From trigonometry: radius = distance × sin( diameter_angle / 2 ) = 1,590 × sin( 25′/2 ) = 6 ly.
  4. ↑ "NGC 6405". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2018-12-08.
  5. 1 2 Adam, Len (2018), Imaging the Messier Objects Remotely from Your Laptop, The Patrick Moore Practical Astronomy Series, Springer, p. 73, Bibcode:2018imor.book.....A, ISBN   978-3319653853
  6. 1 2 Paunzen, E.; et al. (July 2006), "CCD photometric search for peculiar stars in open clusters. VII. Berkeley 11, Berkeley 94, Haffner 15, Lyngå 1, NGC 6031, NGC 6405, NGC 6834 and Ruprecht 130", Astronomy and Astrophysics, 454 (1): 171–178, arXiv: astro-ph/0602567 , Bibcode:2006A&A...454..171P, doi:10.1051/0004-6361:20054628, S2CID   5131254.
  7. 1 2 Burnham, Robert (1978), Burnham's Celestial Handbook: An Observer's Guide to the Universe Beyond the Solar System, Dover books on astronomy and astrophysics, vol. 3, Courier Corporation, p. 1705, ISBN   978-0486236735.
  8. 1 2 3 Kılıçoğlu, T.; et al. (March 2016), "Chemical Composition of Intermediate-mass Star Members of the M6 (NGC 6405) Open Cluster", The Astronomical Journal, 151 (3): 30, arXiv: 1510.05385 , Bibcode:2016AJ....151...49K, doi: 10.3847/0004-6256/151/3/49 , S2CID   118553511, 49.
  9. 1 2 Netopil, M.; et al. (January 2016), "On the metallicity of open clusters. III. Homogenised sample", Astronomy & Astrophysics, 585: 17, arXiv: 1511.08884 , Bibcode:2016A&A...585A.150N, doi:10.1051/0004-6361/201526370, S2CID   118382876, A150.
  10. ↑ Eggen, O. J. (February 1973), "Some variables of spectral type K", Publications of the Astronomical Society of the Pacific, 85: 42, Bibcode:1973PASP...85...42E, doi:10.1086/129403, S2CID   120272647.
  11. ↑ Garner, Rob (28 August 2017). "Explore - The Night Sky | Hubble's Messier Catalog". Nasa.gov. Retrieved 23 January 2022.
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