NGC 6025
A naked-eye open cluster straddling Norma and Triangulum Australe.
NGC 6025 is an open star cluster in the southern sky, lying near the border between the constellations Triangulum Australe and Norma. It was first recorded by Abbe Lacaille in 1751 during his expedition to the Cape of Good Hope. The cluster appears in the Caldwell catalogue as object 95. Its distance from the Sun is about 739.0 parsecs, and it has an apparent visual magnitude of 5.1, making it visible to the naked eye, though large binoculars provide a better view. Its Trumpler classification is II3p, meaning it is a detached cluster with little central concentration, composed of fewer than 50 stars that range from moderately bright to faint. The brightest star, MQ Triangulum Australis, shines at magnitude 7.1 and is a blue straggler with a stellar type of B1Ve. The cluster is moderately young, with an estimated age between 40 and 69 million years, and is richer in metals than the Sun—even more so than the Hyades cluster. Seven spectroscopic binary systems have been identified within it, along with one blue straggler and two Be star candidates. The cluster straddles the official IAU boundary between Norma and Triangulum Australe, as set by Delporte, with its northern part in Norma and its southern part in Triangulum Australe.
Quick Facts
- Credit
- DECaPS
- Epoch
- J2000
- Constellation
- Triangulum Australe
- Ra
- 16 · 03 · 07.0
- Dec
- −60 · 25 · 48
- Dist Ly
- 739.0 pc
- Appmag V
- 5.1
- Age
- 40 to 69 Myr
- Names
- Caldwell 95, Collinder 296, Melotte 139, Lacaille III.10, Dunlop 304
Facts from the source article.
Lore & Background
NGC 6025 was discovered by Abbe Lacaille in 1751 during his expedition to the Cape of Good Hope. The cluster is classified as Trumpler class II3p, indicating a detached cluster with little central condensation, composed of moderately bright and faint stars numbering fewer than 50. It is a moderately young cluster with an age between 40 and 69 Myr and is metal-rich compared to the Sun, more so than the Hyades cluster. The brightest member is MQ Triangulum Australis, a blue straggler of magnitude 7.1 with stellar classification B1Ve. Seven spectroscopic binary star systems have been identified among the members, and only one blue straggler has been found, along with two Be candidates.
Reader's Guide
NGC 6025 is notable as a moderately young, metal-rich open cluster that straddles the IAU boundary between the constellations Norma and Triangulum Australe, as determined by Delporte. Its northern part lies in Norma, its southern part in Triangulum Australe. The cluster contains a single blue straggler, MQ Triangulum Australis, which is also its brightest member, and two Be candidates. The presence of seven spectroscopic binary systems adds to its interest for studies of stellar multiplicity and evolution. Its naked-eye visibility and better appearance through large binoculars make it accessible to amateur observers, while its metal-rich composition relative to the Sun and the Hyades cluster provides a contrast for understanding chemical enrichment in open clusters.
Frequently Asked Questions
What is NGC 6025?
NGC 6025 is a loose, detached open star cluster listed as Caldwell 95. It lies about 739 parsecs from the Sun and shows very little central concentration, with fewer than 50 stars spread in a scattered pattern.
Where in the sky can I find NGC 6025?
The cluster sits right on the border between Triangulum Australe and Norma in the southern sky. Because of that boundary position, different catalogues may assign it to either constellation.
How old is NGC 6025?
Current estimates place its age between 40 and 69 million years. That makes it a relatively young open cluster, still bound together but already beginning to shed its outer stars.
Can I see NGC 6025 with the naked eye?
Yes — at an apparent visual magnitude of 5.1 it is just within naked-eye range under truly dark skies. Most observers, however, find the scattered star pattern far more rewarding through a pair of large binoculars.
Who first recorded NGC 6025?
Abbé Lacaille noted the cluster in 1751 while on his expedition to the Cape of Good Hope. It was later added to Stephen Caldwell's catalogue as object 95.
More in Caldwell Objects 1-16
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