Book contents
- Frontmatter
- Dedication
- Contents
- Foreword
- Preface
- User Guide
- Charles Messier
- The Observations
- The Catalog
- Statistics of the Messier objects
- Visual observation of the Messier objects
- Photography of the Messier objects
- The 110 Messier objects
- M 1
- M 2
- M 3
- M 4
- M 5
- M 6
- M 7
- M 8
- M 9
- M 10
- M 11
- M 12
- M 13
- M 14
- M 15
- M 16
- M 17
- M 18
- M 19
- M 20
- M 21
- M 22
- M 23
- M 24
- M 25
- M 26
- M 27
- M 28
- M 29
- M 30
- M 31
- M 32
- M 33
- M 34
- M 35
- M 36
- M 37
- M 38
- 39
- M 40
- M 41
- M 42
- M 43
- M 44
- M 45
- M 46
- M 47
- M 48
- M 49
- M 50
- M 51
- M 52
- M 53
- M 54
- M 55
- M 56
- M 57
- M 58
- M 59
- M 60
- M 61
- M 62
- M 63
- M 64
- M 65
- M 66
- M 67
- M 68
- M 69
- M 70
- M 71
- M 72
- M 73
- M 74
- M 75
- M 76
- M 77
- M 78
- M 79
- M 80
- M 81
- M 82
- M 83
- M 84
- M 85
- M 86
- M 87
- M 88
- M 89
- M 90
- M 91
- M 92
- M 93
- M 94
- M 95
- M 96
- M 97
- M 98
- M 99
- M 100
- M 101
- M 102
- M 103
- M 104
- M 105
- M 106
- M 107
- M 108
- M 109
- M 110
- Glossary of technical terms
- Index of figures
- Index of sources
M 9
from The 110 Messier objects
Published online by Cambridge University Press: 05 August 2015
Translated by
Book contents
- Frontmatter
- Dedication
- Contents
- Foreword
- Preface
- User Guide
- Charles Messier
- The Observations
- The Catalog
- Statistics of the Messier objects
- Visual observation of the Messier objects
- Photography of the Messier objects
- The 110 Messier objects
- M 1
- M 2
- M 3
- M 4
- M 5
- M 6
- M 7
- M 8
- M 9
- M 10
- M 11
- M 12
- M 13
- M 14
- M 15
- M 16
- M 17
- M 18
- M 19
- M 20
- M 21
- M 22
- M 23
- M 24
- M 25
- M 26
- M 27
- M 28
- M 29
- M 30
- M 31
- M 32
- M 33
- M 34
- M 35
- M 36
- M 37
- M 38
- 39
- M 40
- M 41
- M 42
- M 43
- M 44
- M 45
- M 46
- M 47
- M 48
- M 49
- M 50
- M 51
- M 52
- M 53
- M 54
- M 55
- M 56
- M 57
- M 58
- M 59
- M 60
- M 61
- M 62
- M 63
- M 64
- M 65
- M 66
- M 67
- M 68
- M 69
- M 70
- M 71
- M 72
- M 73
- M 74
- M 75
- M 76
- M 77
- M 78
- M 79
- M 80
- M 81
- M 82
- M 83
- M 84
- M 85
- M 86
- M 87
- M 88
- M 89
- M 90
- M 91
- M 92
- M 93
- M 94
- M 95
- M 96
- M 97
- M 98
- M 99
- M 100
- M 101
- M 102
- M 103
- M 104
- M 105
- M 106
- M 107
- M 108
- M 109
- M 110
- Glossary of technical terms
- Index of figures
- Index of sources
Summary
Degree of difficulty 3 (of 5)
Minimum aperture 30mm
Designation NGC 6333
Type Globular cluster
Class VIII
Distance 46,090 ly (RR Lyr, 1999)
Size 150 ly
Constellation Ophiuchus
R.A. 17h 19.2min
Decl. –18° 31′
Magnitude 7.6
Surface brightness –
Apparent diameter 11′
Discoverer Messier, 1764
History Charles Messier discovered M 9 on the 28 th of May 1764, as a “nebula without star” and added: “it is round & its light faint, 3' diameter.” Exactly 20 years later, William Herschel reported that this object was actually a very rich star cluster. In the 1830s, Admiral Smyth observed M 9 in more detail and noted: “This fine object is composed of a myriad of minute stars, clustering into a blaze in the center, and wonderfully aggregated, with numerous outliers seen by glimpses.” Lord Rosse remarked: “The outline not round; on south side is an outlying portion separated from the chief portion by a dark passage.” The German observer Heinrich d'Arrest, by contrast, believed he saw an “almost double-core cluster” and noted an elongation in the north-south direction.
In 1918, Curtis remarked that M 9 maintained the relatively small diameter of 3' on photographic plates. But modern studies, based on much deeper exposures, have almost quadrupled this number.
Astrophysics M 9 has a distance of about 14,000 light-years from the galactic center, situated on its far side, just beyond the galactic bulge. The distance to us is 46,000 light-years, and its diameter of 150 light-years is quite average, as is its total mass of about 300,000 solar masses.
Because of its position behind the fields of dusty interstellar clouds in Ophiuchus, M 9 suffers from about one magnitude of interstellar absorption, in particular in its northern and western parts. Also, according to Shapley, M 9 did not appear exactly spherical, he rather regarded it as slightly elliptical (0.9).
The brightest individual star of M 9 reaches magnitude 13.5, the mean magnitude of the 25 brightest cluster members is 15.5. 16 RR Lyrae stars have been cataloged for M 9, and two other variables, one of which is a type II cepheid.
Information
- Type
- Chapter
- Information
- Atlas of the Messier ObjectsHighlights of the Deep Sky, pp. 93 - 94Publisher: Cambridge University PressPrint publication year: 2008
Accessibility standard: Unknown
Why this information is here
This section outlines the accessibility features of this content - including support for screen readers, full keyboard navigation and high-contrast display options. This may not be relevant for you.Accessibility Information
Accessibility compliance for the PDF of this book is currently unknown
and may be updated in the future.