Messier 13

Database links to Messier 13

Globular cluster Messier 13

Image taken with the 81 cm reflecting telescope at the Mount Lemmon Observatory
AladinLite
Constellation	Hercules
Position equinox : J2000.0 , epoch : J2000.0
Right ascension	16 ^h 41 ^m 41.6 ^s
declination	+ 36 ° 27 ′ 41 ″
Appearance
Concentration class	V
Brightness (visual)	5.8 likes
Angular expansion	20 ′
Physical data
Affiliation	Milky Way
Integrated spectral type	F6
Redshift	−0.000822 ± 0.000003
Radial velocity	(−246.6 ± 0.9) km / s
distance	25.1 kLj (7.7 kpc )
diameter	145 ly
history
discovery	Edmond Halley
Discovery date	1714
Catalog names
M 13 • NGC 6205 • C 1639 + 365 • GCl 45 •

Messier 13 or M13 , also known as Hercules Cluster or NGC 6205 , is a bright globular cluster in the constellation Hercules with the number 13 in the Messier catalog .

properties

M13 is the brightest globular cluster in the northern sky and was discovered by the English astronomer Sir Edmond Halley as early as 1714 . It is about 25,100 light years away from the sun (the figures vary between 23,000 and 26,000 ly), has 300,000 times the luminosity of the sun and a diameter of 150 light years.

Core of Messier 13 ( Hubble recording)

map

M13 has an apparent magnitude of 5.8 mag. It can already be seen as a misty spot in prism binoculars , in some cases even with clear eyes . In a telescope with an opening of around 10 cm or more, it can be resolved into single stars at the edge and is therefore a worthwhile object for amateur astronomers . You can find it - best in spring or summer - on the "right side of the square" of Hercules, between the stars η and ξ Her. The little card from the summer sky is suitable for searching for the constellation .

Early observation history

M13 was discovered by Edmond Halley in 1714 as a nebula just visible to the naked eye. In 1764, Charles Messier observed the M13. With his reflector telescope he could not see any single stars, only a round and shiny "nebula" that became brighter in the middle. William Herschel then resolved M13 into single stars in 1783 with a much larger telescope. In the 19th century, d'Arrest and Schönfeld documented their observations using medium-sized instruments.

M13 on a 19th century astronomical drawing ( Trouvelot , 1881)

Diagram of M13 (ES Holden 1891) with marked - alleged - interfaces of the channels

The first drawing has come down to us from Herschel; just like a later drawing by Secchi , however, these are only sketches. The best drawing is a work by Trouvelot , which was created around 1877 on the 14-inch refractor (lens telescope) at the Cambridge observatory. Trouvelot shows 171 single stars , of which, according to Schreiner, " many are drawn in the marginal parts in accordance with the photograph ". A drawing by Lord Rosse published in 1861 shows three sharply delineated, star-free channels that merge towards the center of the star cluster. An independent review conducted by Harrington of Ann Arbor in 1887 appeared to confirm the existence of the canals.

The first known photograph of M13 comes from Henry (1887, Paris), on which, with an exposure time of 2 hours, the edge areas were completely resolved, but the center of M13 was only partially resolved into individual stars. J. Schreiner now used the photographic refractor of the Astrophysical Observatory Potsdam to take a one-hour and a two-hour picture in September 1891. The month before, Holden and Campbell had completed a series of seven recordings (17–170 minutes) at the Lick Observatory . Holden recognized "channels or lanes" which should meet at 13 points (see diagram). He thought he found structural features here that indicate the forces of origin of M13. Schreiner, however, did not find the canals visually or on the photographic plates he had made. For him, it was a matter of fluctuations in star density, which could be caused solely by chance processes.

Arecibo message

M13 was the target of the Arecibo embassy radio signal . A strong signal was sent from the Arecibo radio telescope to establish contact with a possible extraterrestrial civilization . The globular cluster was chosen because many stars are gathered here in a relatively small space, which should increase the chance of encountering an inhabited world. However, taking into account the long signal propagation time, the answer from a technically developed civilization would arrive on earth after about 45,600 years at the earliest.

M13 in literature

The star cluster M13 has played an important role as the home of the fictional Arkonide people in the science fiction series Perry Rhodan since 1961 .