Planetary Nebula M2-9

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"Butterfly Nebula" redirects here. For other uses, see Butterfly Nebula (disambiguation).

Observation data (Epoch J2000)
Planetary Nebula M2-9

Right ascension	17^h 05^m 37.952^s^[1]
Declination	-10° 08′ 34.58″^[1]
Distance	2,100 ly (650 pc)^[2]
Apparent magnitude (V)	14.7^[1]
Apparent dimensions (V)	115″^[2] × 18″^{[citation needed]}
Constellation	Ophiuchus
Physical characteristics
Radius	0.7 ly (0.2 pc)^[2]^[a]
Absolute magnitude (V)	5.6^[b]
Notable features	Bipolar outflow, Bipolar nebula
Other designations	Twin Jet Nebula,^[1] Butterfly Nebula,^[1] Wings of a Butterfly^[3]
See also: Planetary nebula, Lists of nebulae

M2-9 (also known as Wings of a Butterfly Nebula or just Butterfly Nebula, and Twin Jet Nebula) is a planetary nebula (PN). This bipolar nebula takes the peculiar form of twin lobes of material that emanate from a central star. Astronomers have dubbed this object as the Twin Jet Nebula because of the polar jets believed to cause the shape of the lobes. Its form also resembles the wings of a butterfly, for which it is sometimes referred as the Wings of a Butterfly Nebula. The outer shell is estimated to be about 1,200 (Schwarz et al. 1997) years old.

M2-9 was discovered by Rudolph Minkowski in 1947. The M in M2-9 does not stand for Messier object. The nebula was imaged by the Hubble Space Telescope in the 1990s.

The Wings of a Butterfly Nebula is about 2,100 light-years away from Earth in the direction of the constellation Ophiuchus.

It represents the spectacular "last gasp"^{[citation needed]} of a binary star system at the nebula's center. One component of this binary is the hot core of a star that reached the end of its main-sequence life cycle, ejected most of its outer layers and became a red giant, and is now contracting into a white dwarf. Early in its life the main component of the system was believed to be a sun-like star.

This central star is one of a very closely orbiting pair - the smaller star may even have been engulfed by the other's expanding stellar atmosphere. The resulting interaction has created the stunning planetary nebula.

The nebula has inflated dramatically^[4] due to a fast stellar wind, blowing out into the surrounding disk and inflating the large, wispy hourglass-shaped wings perpendicular to the disk. These wings produce the butterfly appearance when seen in projection.

Astronomers theorize that the gravity of one star pulls some of the gas from the surface of the other and flings it into a thin, dense disk extending into space.^{[citation needed]} Such a disk can successfully account for the jet-exhaust-like appearance of M2-9.^{[citation needed]}

An animated gif of the precessing jet in M2-9 [1]

1 See also
2 Notes
3 References
4 External links

[edit] See also

[edit] Notes

^{^} Radius = distance × sin(angular size / 2) = 2.1 kly * sin(115″ / 2) = 0.6 ly
^{^} 14.7 apparent magnitude - 5 * (log₁₀(650 pc distance) - 1) = 5.6 absolute magnitude