Astronomy:19 Fortuna

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19 Fortuna (historical)
Discovery
Discovered byJohn Russell Hind
Discovery siteGeorge Bishop's Observatory
Discovery date22 August 1852
Designations
(19) Fortuna
Pronunciation/fɔːrˈtjuːnə/[1]
Named afterFortūna
A902 UG
Minor planet categoryMain belt
AdjectivesFortunian /fɔːrˈtjuːniən/
Orbital characteristics[2]
Epoch 21 November 2025 (JD 2461000.5)
|{{{apsis}}}|helion}}2.828 AU
|{{{apsis}}}|helion}}2.056 AU
2.442 AU
Eccentricity0.159
Orbital period3.816 yr (1393.907 d)
Mean anomaly96.500°
Inclination1.573°
Longitude of ascending node211.001°
182.515°
Earth MOID1.062 AU
Jupiter MOID2.601 AU
TJupiter3.483
Physical characteristics
Dimensions(225 × 205 × 195) ± 12 km[3]
(242 × 203 × 192) ± 10 km[4]
Mean diameter211±2 km[4]
225 km[5][6]
Flattening0.21[lower-alpha 1]
Mass(8.8±1.4)×1018 kg[4]
12.7×1018 kg[3]
Mean density1.80±0.29 g/cm3[4]
2.70±0.48 g/cm3[3]
Equatorial surface gravity
~0.0629 m/s²
Equatorial escape velocity
~0.1190 km/s
Rotation period7.4432 h (0.3101 d)[2]
7.443224±0.000001 h[4]
Axial tilt29°[4]
Pole ecliptic latitude60°±3°[4]
Pole ecliptic longitude103°±3°[4]
Geometric albedo0.056[4]
0.037[2]
Physics~180 K
G[2]
Apparent magnitude8.88[7] to 12.95
Absolute magnitude (H)7.49[2]
7.13[4]
Angular diameter0.25" to 0.072"


19 Fortuna is one of the largest main-belt asteroids. It has a composition similar to 1 Ceres: a darkly colored surface that is heavily space-weathered with the composition of primitive organic compounds, including tholins.

Fortuna is 225 km in diameter and has one of the darkest known geometric albedos for an asteroid over 150 km in diameter. Its albedo has been measured at 0.028 and 0.037.[8] The spectra of the asteroid displays evidence of aqueous alteration.[9]

History

Discovery

Fortuna was discovered by English astronomer John Russell Hind on the evening of 22 August 1852.[10] He was observing from George Bishop's Observatory in London, England, when he spotted a magnitude 9 object with a yellowish color (possibly caused by the atmosphere).[10][11] His discovery was announced in the scientific journal Astronomische Nachrichten on 31 August.[10]

Name and symbol

Soon after discovery, the observatory's owner George Bishop encouraged Hind to choose a name for the asteroid.[11] He chose "Fortuna", after the Roman goddess of fortune and misfortune.[12]: 15  No astronomical symbol was provided in Hind's discovery announcements. A symbol of a star over Fortune's wheel 19 Fortuna symbol (U+1CECC 𜻌) appeared in the book An Astronomical Vocabulary, written by Hind and published on the year of Fortuna's discovery, but no explanation for the symbol was provided.[13]: 9 

Orbit

Fortuna orbits the Sun with an average distance (or semi-major axis of 2.44 astronomical units (AU), an orbital period of 3.82 years, and an orbital inclination of 1.57°,[2] placing it within the inner main asteroid belt.[14]: 87  Along its elliptical orbit, its distance from the Sun varies between 2.06 AU at perihelion to 2.83 AU at aphelion due to an orbital eccentricity of 0.16.[2] It does not belong to any known asteroid family, making it a background asteroid.[15]

Physical characteristics

The Hubble Space Telescope observed Fortuna in 1993. It was resolved with an apparent diameter of 0.20 arcseconds (4.5 pixels in the Planetary Camera) and its shape was found to be nearly spherical. Satellites were searched for but none were detected.

Stellar occultations by Fortuna have been observed several times. Fortuna has been studied by radar.[16]

Fortuna has been perturbed by the 80 km 135 Hertha and was initially estimated by Baer to have a mass of 1.08×1019 kg.[6] A more recent estimate by Baer suggests it has a mass of 1.27×1019 kg.[3]

Notes

  1. ↑ Flattening derived from the maximum aspect ratio (c/a): f=1−ca, where (c/a) = 0.79±0.05.[4]

References

  1. ↑ Noah Webster (1884) A Practical Dictionary of the English Language
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 "JPL Small-Body Database Browser: 19 Fortuna". http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=19. Retrieved 2024-12-21. 
  3. ↑ 3.0 3.1 3.2 3.3 Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. http://home.earthlink.net/~jimbaer1/astmass.txt. Retrieved 2008-11-27. 
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 P. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56
  5. ↑ Storrs, AlexExpression error: Unrecognized word "etal". (1998). "Imaging Observations of Asteroids with Hubble Space Telescope". Icarus 137 (2): 260–268. doi:10.1006/icar.1999.6047. Bibcode: 1999Icar..137..260S. Archived from the original on 25 February 2012. https://web.archive.org/web/20120225134811/http://scripts.mit.edu/~paleomag/articles/Storrs_1999_Icarus.pdf. Retrieved 2005-01-15. 
  6. ↑ 6.0 6.1 "Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris". Celestial Mechanics and Dynamical Astronomy (Springer Science+Business Media B.V. 2007) 100 (2008): 27–42. 2008. doi:10.1007/s10569-007-9103-8. Bibcode: 2008CeMDA.100...27B. 
  7. ↑ "AstDys (19) Fortuna Ephemerides". Department of Mathematics, University of Pisa, Italy. https://newton.spacedys.com/astdys/index.php?pc=1.1.3.1&n=19&oc=500&y0=1963&m0=10&d0=31&h0=0&mi0=0&y1=1963&m1=10&d1=31&h1=0&mi1=0&ti=1.0&tiu=days. Retrieved 2010-06-27. 
  8. ↑ Storrs, Alex et al. (2005). "A closer look at main belt asteroids 1: WF/PC images". Icarus 173 (2): 409–416. doi:10.1016/j.icarus.2004.08.007. Bibcode: 2005Icar..173..409S. Archived from the original on April 18, 2007. https://web.archive.org/web/20070418034343/http://web.mit.edu/bpweiss/www/StorrsWeiss2005AsteroidsHSTIcarus.pdf. Retrieved 2007-09-23. 
  9. ↑ Fornasier, S. et al. (February 1999), "Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites", Astronomy and Astrophysics Supplement 135: 65–73, doi:10.1051/aas:1999161, Bibcode: 1999A&AS..135...65F, https://ui.adsabs.harvard.edu/link_gateway/1999A&AS..135...65F/PUB_PDF. 
  10. ↑ 10.0 10.1 10.2 Hind, John R. (August 1852). "Entdeckung eines neuen Planeten, von Herrn Hind in London". Astronomische Nachrichten 35: 79–80. 
  11. ↑ 11.0 11.1 Hind, J. R. (June 1852). "Fortuna". Monthly Notices of the Royal Astronomical Society 12 (8): 192. doi:10.1093/mnras/12.8.192. 
  12. ↑ Schmadel, Lutz D. (2003). Dictionary of minor planet names. 1 (5th ed.). Berlin Heidelberg New York: Springer-Verlag. pp. 16. doi:10.1007/978-3-540-29925-7_13. ISBN 3-540-00238-3. 
  13. ↑ Bala, Gavin Jared; Miller, Kirk (18 September 2023). "Unicode request for historical asteroid symbols". Unicode. https://www.unicode.org/L2/L2023/23207-historical-asteroids.pdf. 
  14. ↑ Blanco, C. (February 1996). "Earth-bound observations of asteroid 19 Fortuna imaging : lightcurves, pole direction and shape". Planetary and Space Science 44 (2): 87–91. doi:10.1016/0032-0633(95)00079-8. 
  15. ↑ "(19) Irene – Proper Elements". Asteroids Dynamic Site. https://newton.spacedys.com/astdys/index.php?pc=1.1.6&n=19. Retrieved 19 April 2026. 
  16. ↑ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. http://echo.jpl.nasa.gov/asteroids/. Retrieved 2011-10-30. 



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