Zhúlóng (galaxy)
{{one source|date=April 2025}}
{{Short description|Galaxy in the constellation Sextans}}
{{Use dmy dates|date=March 2025}}
{{Sky|10|00|29.97|+|02|05|34.51}}
{{Infobox Galaxy
| name = Zhúlóng
| image = Zhúlóng - The most distant spiral galaxy.jpg
| caption= Zhúlóng imaged by the James Webb Space Telescope
| alt = The image of Zhúlóng, the most distant spiral galaxy discovered to date. It has remarkably well-defined spiral arms, a central old bulge, and a large star-forming disk, resembling the structure of the Milky Way.
| epoch = J2000
| constellation name = Sextans
| h_radial_v =
| dist_ly = {{Convert|12.8|Gly|Gpc|order=flip|abbr=on|lk=on}}
| group_cluster =
| type =
| size = ~{{convert|19|kpc|ly|abbr=on|lk=on|order=flip}} (estimated)
| appmag_v =
| size_v = {{Val|3|×|3|u=arcsecond}}
| notes = Most distant known grand design spiral galaxy
| names =
}}
Zhúlóng is an extremely massive grand-design spiral galaxy located at a redshift distance of z=5.2 (12.8 Gly) in the constellation of Sextans. It is believed to be the most distant known grand design spiral galaxy. Spiral galaxies beyond red shift 3.0 are generally rare with only a few known.{{Cite web |title=Astronomers discover an ultra-massive grand-design spiral galaxy |url=https://phys.org/news/2024-12-astronomers-ultra-massive-grand-spiral.amp |access-date=2025-04-22 |website=phys.org |language=en}}
The galaxy has well-defined spiral arms that have dense star formation regions while the core is quiescent. However the rate of star formation is low forming 66 solar masses of stars per year. The size of this galaxy is comparable to the Milky Way galaxy, being an estimated 62,000 light years in diameter. It has a mass of around 100 billion solar masses.{{Cite web |date=2025-04-16 |title=Webb Discovers Milky Way-Like Spiral Galaxy in Early Universe {{!}} Sci.News |url=https://www.sci.news/astronomy/zhulong-galaxy-13834.html |access-date=2025-04-22 |website=Sci.News: Breaking Science News |language=en-US}}
Naming
The galaxy was named Zhúlóng meaning “Torch Dragon” in Chinese mythology. In the myth, Zhúlóng is a powerful red solar dragon that creates day and night by opening and closing its eyes, symbolizing light and cosmic time.{{cite web |date=16 April 2025 |title=The most distant cousin of the Milky Way ever observed |url=https://www.unige.ch/medias/en/2025/la-plus-lointaine-cousine-de-la-voie-lactee-jamais-observee |access-date=20 April 2025 |publisher=University of Geneva}}
Discovery
Zhúlóng was discovered by a team led by Mengyuan Xiao, and announced in a paper submitted to Astronomy & Astrophysics on 17 December 2024, and published on 16 April 2025.{{cite journal|doi=10.1051/0004-6361/202453487 | doi-access=free |title=PANORAMIC: Discovery of an ultra-massive grand-design spiral galaxy at z ∼ 5.2 |date=2025 |last1=Xiao |first1=Mengyuan |last2=Williams |first2=Christina C. |last3=Oesch |first3=Pascal A. |last4=Elbaz |first4=David |last5=Dessauges-Zavadsky |first5=Miroslava |last6=Marques-Chaves |first6=Rui |last7=Bing |first7=Longji |last8=Ji |first8=Zhiyuan |last9=Weibel |first9=Andrea |last10=Bezanson |first10=Rachel |last11=Brammer |first11=Gabriel |last12=Casey |first12=Caitlin |last13=Cloonan |first13=Aidan P. |last14=Daddi |first14=Emanuele |last15=Dayal |first15=Pratika |last16=Faisst |first16=Andreas L. |last17=Franx |first17=Marijn |last18=Glazebrook |first18=Karl |last19=Hutter |first19=Anne |last20=Kartaltepe |first20=Jeyhan S. |last21=Labbe |first21=Ivo |last22=Lagache |first22=Guilaine |last23=Lim |first23=Seunghwan |last24=Magnelli |first24=Benjamin |last25=Martinez |first25=Felix |last26=Maseda |first26=Michael V. |last27=Nanayakkara |first27=Themiya |last28=Schaerer |first28=Daniel |last29=Whitaker |first29=Katherine E. |journal=Astronomy & Astrophysics |volume=696 |pages=A156 |bibcode=2025A&A...696A.156X |arxiv=2412.13264}} The discovery was surprising to astronomers, who had previously believed that spiral galaxies took billions of years to develop.
Image gallery
File:Zhúlóng - The most distant spiral galaxy (full).jpg|PANORAMIC Survey showing position of Zhúlóng, imaged by the James Webb Space Telescope
References
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