Butterfly Cluster

Coordinates: Sky map 17h 40.1m 00s, −32° 13′ 00″
Source: Wikipedia, the free encyclopedia.
Not to be confused with butterfly cluster compound.
Butterfly Cluster
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
ConstellationScorpius
See also: Open cluster, List of open clusters

The Butterfly Cluster (cataloged as Messier 6 or M6, and as NGC 6405) is an

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]

The first astronomer to record the Butterfly Cluster's existence was

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

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

References

  1. ^
    S2CID 6066790
    .
  2. ^ a b 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. ^ a b 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. ^
    ISBN 978-3319653853
  6. ^
    S2CID 5131254
    .
  7. ^
    ISBN 978-0486236735
    .
  8. ^
    S2CID 118553511
    , 49.
  9. ^
    S2CID 118382876
    , A150.
  10. S2CID 120272647
    .
  11. ^ Garner, Rob (28 August 2017). "Explore - The Night Sky | Hubble's Messier Catalog". Nasa.gov. Retrieved 23 January 2022.

External links

Wikimedia Commons has media related to Messier 6.
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