| NGC 3603 | |
|---|---|
HST image of NGC 3603 |
|
| Observation data (J2000 epoch) | |
| Constellation | Carina |
| Right ascension | 11h 15m 09.1s[1] |
| Declination | -61° 16′ 17″[1] |
| Distance | 20 kly[2] (6.1 kpc) |
| Apparent magnitude (V) | 9.1[1] |
| Apparent dimensions (V) | 3′[2] |
| Physical characteristics | |
| Mass | - M☉ |
| Radius | - |
| Estimated age | - |
| Notable features | Central region is the young cluster HD 97950[1] |
| See also: Open cluster, List of open clusters | |
NGC 3603 is an open cluster of stars situated in the Carina spiral arm of the Milky Way around 20,000 light-years away from the Solar System.
NGC 3603 has been subject to intense study as a starburst region for more than a century because it represents a unique combination of proximity, low visual extinction, brightness and compactness.[3]
It was observed by John Herschel on the 14th of March 1834 during his visit to South Africa, who remarked that it was "a very remarkable object...perhaps a globular cluster". Herschel catalogued it as nebula 3334 in his Results of Astronomical Observations made at the Cape of Good Hope, published in 1847. In 1864 the Royal Society published his General Catalogue of Nebulae and Clusters, where he listed it as number 2354. It was subsequently incorporated into the New General Catalogue as by J. L. E. Dreyer as NGC 3603.[4]
Contents |
It is surrounded by the most massive visible cloud of glowing gas and plasma known as a H II region in the Milky Way.[5] HD 97950[6] is the central star of star cluster, the densest concentration of very massive stars known in the galaxy.[7] Strong ultraviolet radiation and stellar winds have cleared the gas and dust, giving an unobscured view of the cluster.[8]
Three prominent Wolf-Rayet stars have been detected within the cluster.[9] These three massive stars have been observed and their solar mass measured using the Very Large Telescope. The largest of the three, NGC 3603-A1 is a blue double star that orbit around each other once every 3.77 days. The two combined have a solar mass that is 200 times more massive than our Sun: (A1-a) is the largest known star in our galaxy with an estimated mass of 116 solar masses, while its companion (A1-b) has a mass of 89 solar masses.[10]
NGC 3603 is visible in the telescope as a small rather insignificant nebulosity with a yellowish tinge due to the effects of interstellar absorption. In the mid-1960s optical studies coincided with radio astronomical observations which showed it to be an extremely strong thermal radio source. Later observations in other galaxies introduced the concept of 'starburst' regions, in some cases whole galaxies, of extremely rapid star formation and NGC 3603 is now considered to be such a region.
In 1987 a supernova (known as SN 1987A) occurred in the Large Magellanic Cloud. This was the first supernova to be close enough for detailed observation with satellite based telescopes. One result was the discovery that prior to the main explosion it had thrown off a relatively small amount of material in a very distinctive pattern, a bit like an hourglass perpendicular to a detached glowing ring. One star in NGC 3603 (Sher 25, the number comes from the 1960s optical observations) was found to have thrown off matter in a pattern similar to that found for the supernova 1987A. This coincidence has aroused intense interest.
Nine objects have been observed in J and H bands that exhibit brown dwarf-like features but are too luminous for the distance it is in the cluster. The objects are being proposed as field brown dwarfs (in front of the cluster) or stars that have recently swallowed a planet.[11]
|