M6

M6 = NGC6405 ( 17h 40.1m -32°13´, 4.2 mag. )
M6 forms a spectacular pair with M7. These two bright, large open clusters in Scorpius was known since antiquity and M7 was listed by Ptolemy. Messier observed both on May 23, is1764.

M6 The Butterfly Cluster
Description: open cluster
Constellation: Scorpius
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M6 is a galactic, or open cluster of stars found in the constellation of Scorpius. It has a diameter of about 20 light-years and lies about 2,000 light-years from Earth.

M6 (NGC 6405) is the second-best cluster of the constellation (after M7). This is an open cluster which sometimes bears the name "The Butterfly Cluster". Its brightest star is BM Scorpii, a sixth-magnitude yellow giant.

M6 motorway
The M6 motorway is the longest motorway in the United Kingdom.

M6 (NGC 6405, Butterfly Cluster)
M7 (NGC 6475, Ptolemy's Cluster)
M8 (NGC 6523, Lagoon Nebula)
M11 (NGC 6705, Wild Duck Cluster)
M13 (NGC 6205, Great Cluster in Hercules)
M16 (NGC 6611)
M17 (NGC 6618, Omega Nebula) ...

A lovely sight in binoculars or telescope, fifth magnitude (5.0) 30 Herculis is a quite reddish class M (M6) giant that lies 360 light years away.

Conceiving the line NN' to be that of the nodes at any time, and the earth and lunar orbit to be moving in the direction of the straight arrows, the earth will be on one side of the ecliptic from M2 to M5, and on the other side from M6 to M 1, ...

4 +18 19 54 M6-III 5.91 1.47 869 rho ARI 02 56 26.1 +18 01 23 F6V 5.63 0.43 847 sigma ARI 02 51 29.5 +15 04 55 B7V 5.49 -0.09 1005 tau ARI 03 21 13.6 +21 08 49 B5IV 5.28 -0.07 1015 tau ARI 03 22 45.2 +20 44 31 K3III 5.09 1.24 522 01 48 10.

This often even dimmer, main sequence red dwarf star (M6.0 Ve) may have only 10 percent of Sol's mass (Geyer et al, 1988; and RECONS estimate), 14 percent of its diameter (Johnson and Wright, 1983, page 649), and less than 4/100, ...

C has been analyzed in normal (i.e. not metal-weak) K5 - M6 giants by Lazaro eta l. (1991) using the 2.3 µm band of CO. They find a systematic depletion of C with respect to the sun, the average deficiency being -0.6 dex.

M4 (globular cluster)
M6 The Butterfly Cluster (open cluster)
M7 Ptolemy's Cluster (open cluster)
M80 (globular cluster) ...

This is usually in the range of M6.5 to M9.5. The spectrum of an M star shows lines belonging to molecules and all neutral metals but hydrogen lines are usually absent. Titanium oxide can be strong in M stars, usually dominating by about M5.

The sequence of images shown above spans more than a nine hour period from 12:07 to 21:20 Universal Time (UT), (7:07am to 4:20pm central daylight savings time). The data include two M-class flares: an M6.

It changes brightness as it pulsates due to upward traveling shock waves, with a long period due to its large distended size of the star, which is an M6 . However, the spectral type changed from M8 at minimum brightness to M2 at maximum brightness.

See also: Star, Light, Cluster, Sky, Constellation