NGC 6302
| Nebula | |
|---|---|
 |
|
| Observation data: J2000 epoch | |
| Right ascension | 17h 13m 44.211s |
| Declination | −37° 06′ 15.94″ |
| Distance | 3.4 ± 0.5 kly (1.04 ± 0.16 kpc) ly |
| Apparent magnitude (V) | 7.1B |
| Apparent dimensions (V) | >3′.0 |
| Constellation | Scorpius |
| Physical characteristics | |
| Radius | >1.5 ± 0.2 ly ly |
| Absolute magnitude (V) | -3.0B +0.4 −0.3 |
| Notable features | Dual chemistry, hot central star |
| Designations |
Bipolar Nebula, Bug Nebula, |
Bipolar Nebula, Bug Nebula,
NGC 6302, also called the Bug Nebula, Butterfly Nebula, is a bipolar planetary nebula in the constellation Scorpius. The structure in the nebula is among the most complex ever observed in planetary nebulae. The spectrum of NGC 6302 shows that its central star is one of the hottest stars in the galaxy, with a surface temperature in excess of 200,000 K, implying that the star from which it formed must have been very large (cf. PG 1159 star).
The central star, a white dwarf, was only recently discovered (Szyszka et al. 2009), using the upgraded Wide Field Camera 3 on board the Hubble Space Telescope. The star has a current mass of around 0.64 solar masses. It is surrounded by a particularly dense equatorial disc composed of gas and dust. This dense disc is postulated to have caused the star's outflows to form a bipolar structure (Gurzadyan 1997) similar to an hour-glass. This bipolar structure shows many interesting features seen in planetary nebulae such as ionization walls, knots and sharp edges to the lobes.
As it is included in the New General Catalogue, this object has been known since at least 1888. The earliest known study of NGC 6302 is by Edward Emerson Barnard, who drew and described it in 1907.
Since then it has been the focus of many works and displays many interesting characteristics worthy of study. Interest in recent years has shifted from discussions over the excitation method in the nebula (shock-excitation or photo-ionisation) to the properties of the large dust component.
It featured in some of the first images released after the final servicing mission of the Hubble Space Telescope in September 2009.
NGC 6302 has a complex structure, which may be approximated as bipolar with two primary lobes, though there is evidence for a second pair of lobes that may have belonged to a previous phase of mass loss. A dark lane runs through the waist of the nebula obscuring the central star at all wavelengths. Observations of NGC 6302 suggest that there may be an orthogonal skirt (or chakram) similar to that found in Menzel 3 The nebula is orientated at an angle of 12.8° against the plane of the sky.
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