Milky Way ❍｜appendage｜___｜20260628174208-01-•

Milky Way	…
The Galactic Center as seen from Earth’s night sky (featuring the telescope’s laser guide star). Listed after this infobox is information about the Galactic Center.	…
Observation data (J2000 epoch)	…
Constellation	Sagittarius
Right ascension	17 $^{h}$ 45 $^{m}$ 40.03599 $^{s}$ ¹
Declination	−29° 00′ 28.1699″¹
Distance	7.935–8.277 kpc (25,881–26,996 ly)²³⁴⁵
Characteristics	…
Type	Sb; Sbc; SB(rs)bc⁶⁷
Mass	1.15×10 $^{12}$ ⁸⁹¹⁰ M $_{☉}$
Number of stars	100–400 billion ((1–4)×10 $^{11}$ )¹¹¹²
Size	26.8 ± 1.1 kpc (87,400 ± 3,600 ly) (diameter; D $_{25}$ isophote)¹³¹⁴
Half-light radius (physical)	5.75±0.38 kpc¹⁵
H I scale length (physical)	70 kpc (228,000 ly)¹⁶
Thickness of thin disk	220–450 pc (718–1,470 ly)¹⁷
Thickness of thick disk	2.6 ± 0.5 kpc (8,500 ± 1,600 ly)¹⁷
Angular momentum	~1×10 $^{67}$ J s¹⁸
Sun’s Galactic rotation period	212 Myr¹⁹
Spiral pattern rotation period	220–360 Myr²⁰
Bar pattern rotation period	160–180 Myr²¹
Speed relative to CMB rest frame	552.2±5.5 km/s²²
Escape velocity at Sun’s position	550 km/s²³
Dark matter density at Sun’s position	0.0088 $_{- 0.0018}^{+ 0.0024}$ M $_{☉}$ pc $^{- 3}$ (0.35 $_{- 0.07}^{+ 0.08}$ GeV cm $^{- 3}$ )²³

(echo:: @ ᯤ)

Petrov, L.; Kovalev, Y. Y.; Fomalont, E. B.; Gordon, D. (2011). “The Very Long Baseline Array Galactic Plane Survey—VGaPS”. The Astronomical Journal. 142 (2): 35. arXiv:1101.1460. Bibcode:2011AJ…142…35P. doi:10.1088/0004-6256/142/2/35. ISSN 0004-6256. S2CID 121762178. ↩ ↩²
Event Horizon Telescope Collaboration; et al. (2022). “First Sagittarius A﹡ Event Horizon Telescope Results. VI. Testing the Black Hole Metric”. The Astrophysical Journal. 930 (2): L17. arXiv:2311.09484. Bibcode:2022ApJ…930L..17E. doi:10.3847/2041-8213/ac6756. S2CID 248744741. ↩
Banerjee, Indrani; Sau, Subhadip; SenGupta, Soumitra (2022). “Do shadows of SGR A﹡ and M87﹡ indicate black holes with a magnetic monopole charge?”. arXiv:2207.06034 [gr-qc]. ↩
Abuter, R.; et al. (2019). “A geometric distance measurement to the Galactic center black hole with 0.3% uncertainty”. Astronomy & Astrophysics. 625: L10. arXiv:1904.05721. Bibcode:2019A&A…625L..10G. doi:10.1051/0004-6361/201935656. S2CID 119190574. ↩
The distance towards its center (Sagittarius A﹡). ↩
Gerhard, O. (2002). “Mass distribution in our Galaxy”. Space Science Reviews. 100 (1/4): 129–138. arXiv:astro-ph/0203110. Bibcode:2002SSRv..100..129G. doi:10.1023/A:1015818111633. S2CID 42162871. ↩
Frommert, Hartmut; Kronberg, Christine (August 26, 2005). “Classification of the Milky Way Galaxy”. SEDS. Archived from the original on May 31, 2015. Retrieved May 30, 2015. ↩
Starr, Michelle (March 8, 2019). “The Latest Calculation of Milky Way’s Mass Just Changed What We Know About Our Galaxy”. ScienceAlert.com. Archived from the original on March 8, 2019. Retrieved March 8, 2019. ↩
Watkins, Laura L.; et al. (February 2, 2019). “Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions”. The Astrophysical Journal. 873 (2): 118. arXiv:1804.11348. Bibcode:2019ApJ…873..118W. doi:10.3847/1538-4357/ab089f. S2CID 85463973. ↩
Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2012). “Kinematics of the Stellar Halo and the Mass Distribution of the Milky Way Using Blue Horizontal Branch Stars”. The Astrophysical Journal. 761 (2): 17. arXiv:1210.7527. Bibcode:2012ApJ…761…98K. doi:10.1088/0004-637X/761/2/98. S2CID 119303111. ↩
Frommert, H.; Kronberg, C. (August 25, 2005). “The Milky Way Galaxy”. SEDS. Archived from the original on May 12, 2007. Retrieved May 9, 2007. ↩
Wethington, Nicholos. “How Many Stars are in the Milky Way?”. Archived from the original on March 27, 2010. Retrieved April 9, 2010. ↩
Goodwin, S. P.; Gribbin, J.; Hendry, M. A. (August 1998). “The relative size of the Milky Way”. The Observatory. 118: 201–208. Bibcode:1998Obs…118..201G. ↩
This is the diameter measured using the D $_{25}$ standard. It has been recently suggested that there is a presence of disk stars beyond this diameter, although it is not clear how much of this influences the surface brightness profile. $^{[11]}$ ↩
Lian, Jianhui; Zasowski, Gail; Chen, Bingqiu; Imig, Julie; Wang, Tao; Boardman, Nicholas; Liu, Xiaowei (June 28, 2024), The size of the Milky Way galaxy, arXiv:2406.05604 ↩
Kalberla, Peter M.W.; Kerp, Jürgen (September 1, 2009). “The HI Distribution of the Milky Way”. Annual Review of Astronomy and Astrophysics. 47 (1): 27–61. Bibcode:2009ARA&A..47…27K. doi:10.1146/annurev-astro-082708-101823. ISSN 0066-4146. Retrieved October 23, 2025. ↩
Bland-Hawthorn, Joss; Gerhard, Ortwin (2016). “The Galaxy in Context: Structural, Kinematic, and Integrated Properties”. Annual Review of Astronomy and Astrophysics. 54: 529–596. arXiv:1602.07702. Bibcode:2016ARA&A..54..529B. doi:10.1146/annurev-astro-081915-023441. S2CID 53649594. ↩ ↩²
Karachentsev, Igor. “Double Galaxies § 7.1”. ned.ipac.caltech.edu. Izdatel’stvo Nauka. Archived from the original on March 4, 2016. Retrieved April 5, 2015. ↩
“A New Map of the Milky Way”. Scientific American. April 1, 2020. Archived from the original on April 27, 2021. Retrieved August 10, 2022. ↩
Gerhard, O. (2010). “Pattern speeds in the Milky Way”. arXiv:1003.2489v1 [astro-ph.GA]. ↩
Shen, Juntai; Zheng, Xing-Wu (2020). “The bar and spiral arms in the Milky Way: Structure and kinematics”. Research in Astronomy and Astrophysics. 20 (10): 159. arXiv:2012.10130. Bibcode:2020RAA…20..159S. doi:10.1088/1674-4527/20/10/159. S2CID 229005996. ↩
Kogut, Alan; et al. (December 10, 1993). “Dipole anisotropy in the COBE differential microwave radiometers first-year sky maps”. The Astrophysical Journal. 419: 1–6. arXiv:astro-ph/9312056. Bibcode:1993ApJ…419…1K. doi:10.1086/173453. S2CID 209835274. ↩
Kafle, P.R.; Sharma, S.; Lewis, G.F.; Bland-Hawthorn, J. (2014). “On the Shoulders of Giants: Properties of the Stellar Halo and the Milky Way Mass Distribution”. The Astrophysical Journal. 794 (1): 17. arXiv:1408.1787. Bibcode:2014ApJ…794…59K. doi:10.1088/0004-637X/794/1/59. S2CID 119040135. ↩ ↩²

⏾ Concept Map

Milky Way ❍｜appendage｜___｜20260628174208-01-•

Footnotes