Hubble 5
Planetary nebula in the constellation Sagittarius
From Wikipedia, the free encyclopedia
Hubble 5 (Hb 5) is a large bipolar planetary nebula with a complex shape. The nebula was discovered by American astronomer Edwin Hubble in 1921.[3]
| Emission nebula | |
|---|---|
| Planetary nebula | |
Image of Hb 5 from the Hubble Space Telescope | |
| Observation data: J2000 epoch | |
| Right ascension | 17h 47m 56.25s[1] |
| Declination | −29° 59′ 40.07″[1] |
| Apparent diameter | 52" x 18"[2] |
| Constellation | Sagittarius |
| Designations | PK 359.3-00.1, Hen 2-286, PN G359-3.3-00.9, Sa 2-244, BI 1-E[1] |
Hb 5 has an estimated size of 52" x 18" in Hα.[2] The distance of Hb 5 remains uncertain, with estimates ranging between 0.7 kpc and 2 kpc.[4] The electron temperature of the nebula is 13,000K-16,000K based on the Ne III temperature being lower than the Ne V temperature. The Hβ flux is ~3.0 x 10-12 erg cm⁻² s⁻¹ or 1.19 x 10-10 erg cm⁻² s⁻¹.[5] The nebula is a bipolar, point-symmetric PN.[6]
Central star
Central star is very faint and the presence of the Ne VI line proves that the star is quite hot. The star has a Zanstra temperature ranging from ~100,000 K for hydrogen to ~130,000 K for helium II. The star has a radius of about ~0.17 R☉ and a luminosity of 2 x 10⁴ Lʘ.[2]