Sh 2-305

Sharpless 2-305

Nebula
Image of Sh 2-305 Nebula
Observation data: epoch
Right ascension	07h 30m 4.10s
Declination	−18° 32′ 13.0″ [1]
Distance	13,600  ly    (4,200 [2]   pc)
Constellation	Puppis
Designations	Sh 2-305, RCW 8, LBN 1048 [1]
See also: Lists of nebulae

Sh 2-305 (also known as Sharpless 305) is an H II region and emission nebula located in the constellation Puppis. It is a prominent example of a hot bubble of ionized hydrogen gas, sculpted and illuminated by intense ultraviolet radiation from embedded massive young stars. Sh 2-305 forms part of a larger star-forming complex within the Perseus Arm of the Milky Way and is associated with ongoing stellar birth in dense molecular clouds. ^{[1] [2] [3] [4] [5]}

Charecterstics

The nebula is ionized by a pair of massive O-type stars [VM75] Sh 2-305 4 (O8.5V) ^[6] and [VM75] Sh 2-305 2 (O9.5V) ^[7] accompanied by a pair of B-type stars [VM75] Sh 2-305 7 (B0V) ^[8] and [VM75] Sh 2-305 8 (B0V). ^[9] The stellar population also encompasses a younger generation, including the loose infrared cluster [DBS2003] 5 ^[10] and the open cluster Mayer 3 (also designated C 0727-184). ^[11] This multi-generational assembly reflects sequential star formation triggered by supernova remnants or cloud collisions within the GS234-02 supershell. ^[12] Surrounding the ionized zone are photon-dominated regions (PDRs), transitional layers where far-ultraviolet radiation dissociates molecules and heats dust grains, observable in infrared wavelengths. ^[13]

The region is embedded in a giant molecular cloud complex, part of the star formation region SFR 233.75-0.18. ^[14] Radio and infrared observations reveal dense clumps of gas and dust, with associated water maser emissions indicating active accretion onto protostars. Surveys have identified approximately 116 young stellar objects (YSOs) in the vicinity, underscoring its role as a site of low to intermediate-mass star formation. ^{[15] [16]}

References

1. "Sh 2-305". simbad.cds.unistra.fr. Retrieved 2025-10-28.
2. "Sh 2-305". galaxymap.org. Retrieved 2025-10-28.
3. Astronomy, Go. "Sh2-305 | Nebula in Puppis | GO ASTRONOMY". Go-Astronomy.com. Retrieved 2025-11-04.
4. Lazaro, Enrico de (2021-03-30). "VLT Focuses on Emission Nebula Sharpless 2-305 | Sci.News". Sci.News: Breaking Science News. Retrieved 2025-11-04.
5. [e-mail]. "A starry superbubble". www.eso.org. Retrieved 2025-11-04.
6. "[VM75] Sh 2-305 4". simbad.cds.unistra.fr. Retrieved 2025-11-04.
7. "[VM75] Sh 2-305 2". simbad.cds.unistra.fr. Retrieved 2025-11-04.
8. "[VM75] Sh 2-305 7". simbad.cds.unistra.fr. Retrieved 2025-11-04.
9. "[VM75] Sh 2-305 8". simbad.cds.unistra.fr. Retrieved 2025-11-04.
10. "[DBS2003] 5". simbad.cds.unistra.fr. Retrieved 2025-11-04.
11. "Mayer 3". simbad.cds.unistra.fr. Retrieved 2025-11-04.
12. "[S87c] Loop 235-3". simbad.harvard.edu. Retrieved 2025-11-04.
13. Dewangan, L. K.; Sharma, Saurabh; Pandey, Rakesh; Palacio, S. del; Ojha, D. K.; Benaglia, P.; Baug, T.; Das, S. R. (2020-08-01). "Probing the Physical Conditions and Star Formation Processes in the Galactic H II Region S305". The Astrophysical Journal. 898 (2): 172. arXiv: 2006.03244 . Bibcode:2020ApJ...898..172D. doi: 10.3847/1538-4357/ab9c27 . ISSN   0004-637X.
14. "Star Formation Region Avedisova 2031 | Galaxy Map". galaxymap.org. Retrieved 2025-11-04.
15. Pandey, Rakesh; Sharma, Saurabh; Panwar, Neelam; Dewangan, Lokesh K.; Ojha, Devendra K.; Bisen, D. P.; Sinha, Tirthendu; Ghosh, Arpan; Pandey, Anil K. (2020-03-01). "Stellar Cores in the Sh 2-305 H ii Region". The Astrophysical Journal. 891 (1): 81. arXiv: 2001.04722 . Bibcode:2020ApJ...891...81P. doi: 10.3847/1538-4357/ab6dc7 . ISSN   0004-637X.
16. Bhadari, N. K.; Dewangan, L. K.; Zemlyanukha, P. M.; Ojha, D. K.; Zinchenko, I. I.; Sharma, Saurabh (2021-12-01). "Probing Gas Kinematics and PDR Structure around O-type Stars in the Sh 2-305 H ii Region". The Astrophysical Journal. 922 (2): 207. arXiv: 2109.10334 . Bibcode:2021ApJ...922..207B. doi: 10.3847/1538-4357/ac2a44 . ISSN   0004-637X.