RCW 145

RCW 145

Emission nebula
H II region
RCW 145
Observation data: J2000 epoch
Right ascension	18h 02m 18s
Declination	−23° 30′ 56″ [1]
Distance	8480 [2]   ly    (2500 [3]   pc)
Apparent magnitude (V)	16.8 [4]
Apparent dimensions (V)	1.59° x 1.17°
Constellation	Sagittarius
Physical characteristics
Radius	47 ly
Designations	NGC 6526, Sh 2-26, Sh 2-28, Gum 74
See also: Lists of nebulae

RCW 145 is an emission nebula in the constellation Sagittarius. RCW 145 contains both Sh 2-26 and Sh 2-28. ^[5] It is ionized by the supergiant stars LS 4551 and LS 4538. ^[6] It is possible it is associated with the Trifid nebula. ^[7]

Visibility

RCW 145 is often imaged alongside nearby the nebulae of the Lagoon Nebula and Trifid Nebula. The nebula responds well to Hydrogen-alpha filters. It is also easily visible with a Sulfur II filter, however is not very visible in an Oxygen III filter. It is difficult to image with standard RGB. ^[8]

Westerhout 28

Chandra X-ray Observatory image of Westerhout 28

In the direction of RCW 145 is also the supernova remnant SNR G006.4-00.1 (W28). W28 lies at a further distance of 1800 to 3300 parsecs. It contains multiple pockets of Maser activity. These pockets are 50-100 milliarcseconds in apparent size. ^[9] W 28 is visible in most wavelengths, from radio waves to gamma rays. There is some ionization caused by W 28. It was initially thought to be cause by x-ray emissions, however it has since been determined to be cause by cosmic ray emissions. ^[10]

References

1. "Sh2-28".
2. "Sharpless (Sh2) - Astrobasics". 13 September 2022.
3. Russeil, D. (2003). "Star-forming complexes and the spiral structure of our Galaxy". Astronomy and Astrophysics. 397: 133. Bibcode:2003A&A...397..133R. doi:10.1051/0004-6361:20021504.
4. "Sharpless (Sh2) - Astrobasics". 13 September 2022.
5. "Sh 2-26".
6. "Sh 2-28".
7. Giuliani, A.; et al. (2010). "AGILE detection of GeV γ-ray emission from the SNR W28". Astronomy and Astrophysics. 516. arXiv: 1005.0784 . Bibcode:2010A&A...516L..11G. doi:10.1051/0004-6361/201014256.
8. "SH2-28 (Sharpless 28)".
9. "Supernova Remnant W28 · NRAO/AUI Archives".
10. Phan, V. H. M.; Gabici, S.; Morlino, G.; Terrier, R.; Vink, J.; Krause, J.; Menu, M. (2020). "Constraining the cosmic ray spectrum in the vicinity of the supernova remnant W28: From sub-GeV to multi-TeV energies". Astronomy & Astrophysics. 635: A40. arXiv: 1910.09987 . Bibcode:2020A&A...635A..40P. doi:10.1051/0004-6361/201936927.