Lydia (minor planet designation: 110 Lydia) is a large belt asteroid with an M-type spectrum,[5] and thus may be metallic in composition, consisting primarily of nickel-iron. It was discovered by French astronomer Alphonse Borrelly on 19 April 1870[6] and was named for Lydia, the Asia Minor country populated by Phrygians.[7] The Lydia family of asteroids is named after it.

110 Lydia
110Lydia (Lightcurve Inversion).png
Lightcurve-based 3D-model of Lydia
Discovered byAlphonse Borrelly
Discovery date19 April 1870
(110) Lydia
Named after
A870 HA; 1899 VA; 1972 YS1
Orbital characteristics[2]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc145.80 yr (53,255 d)
Aphelion2.9539 AU (441.90 Gm)
Perihelion2.51115 AU (375.663 Gm)
2.7325 AU (408.78 Gm)
4.52 yr (1649.9 d)
17.99 km/s
0° 13m 5.52s / day
Physical characteristics
Mass6.7×1017 kg
Equatorial surface gravity
0.0241 m/s2
Equatorial escape velocity
0.0455 km/s
  • 10.927 h (0.4553 d)[2]
  • 10.9258 hours[4]
Temperature~168 K

Observations made during 1958–1959 at the McDonald Observatory and in 1969 at the Kitt Peak National Observatory found an uneven light curve with a period of 10.9267 hours.[8] In the late 1990s, a network of astronomers worldwide used light curves to derive spin states and shape models of 10 new asteroids, including (110) Lydia. They obtained a period of 10.92580 hours, with the brightness varying by no more than 0.2 in magnitude.[4]

In the Tholen classification system, it is categorized as an M-type asteroid, while the Bus asteroid taxonomy system lists it as an Xk asteroid.[9] Absorption features in the near infrared are attributed to low-iron, low-calcium orthopyroxene minerals. Water content on the surface is estimated at 0.14–0.27 by mass fraction (wt%).[10] Measurements of the thermal inertia of 110 Lydia give a value between 70 and 200 J·m−2·K−1·s−1/2, compared to 50 for lunar regolith and 400 for coarse sand in an atmosphere.[3] It is a likely interloper in the Padua family of minor planets that share similar dynamic properties.[11]

Lydia occulted a dim star on 18 September 1999.


  1. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  2. ^ a b c d e Yeomans, Donald K., "110 Lydia", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
  3. ^ a b c d Delbo', Marco; Tanga, Paolo (February 2009), "Thermal inertia of main belt asteroids smaller than 100 km from IRAS data", Planetary and Space Science, vol. 57, no. 2, pp. 259–265, arXiv:0808.0869, Bibcode:2009P&SS...57..259D, doi:10.1016/j.pss.2008.06.015.
  4. ^ a b Durech, J.; et al. (April 2007), "Physical models of ten asteroids from an observers' collaboration network", Astronomy and Astrophysics, vol. 465, no. 1, pp. 331–337, Bibcode:2007A&A...465..331D, doi:10.1051/0004-6361:20066347.
  5. ^ a b DeMeo, Francesca E.; et al. (2011), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, 202 (1): 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 17 March 2014, retrieved 11 December 2013. See appendix A.
  6. ^ "Numbered Minor Planets 1–5000", Discovery Circumstances, IAU Minor Planet center, retrieved 7 April 2013.
  7. ^ Schmadel, Lutz D. (2003), Dictionary of Minor Planet Names (5th ed.), Springer, p. 23, ISBN 3-540-00238-3.
  8. ^ Taylor, R. C.; et al. (March 1971), "Minor Planets and Related Objects. VI. Asteroid (110) Lydia", Astronomical Journal, vol. 76, p. 141, Bibcode:1971AJ.....76..141T, doi:10.1086/111097.
  9. ^ DeMeo, Francesca E.; et al. (July 2009), "An extension of the Bus asteroid taxonomy into the near-infrared" (PDF), Icarus, vol. 202, no. 1, pp. 160–180, Bibcode:2009Icar..202..160D, doi:10.1016/j.icarus.2009.02.005, archived from the original (PDF) on 17 March 2014, retrieved 8 April 2013. See appendix A.
  10. ^ Hardersen, Paul S.; Gaffey, Michael J.; Abell, Paul A. (January 1983), "Near-IR spectral evidence for the presence of iron-poor orthopyroxenes on the surfaces of six M-type asteroids", Icarus, vol. 175, no. 1, pp. 141–158, Bibcode:2005Icar..175..141H, doi:10.1016/j.icarus.2004.10.017.
  11. ^ Carruba, V. (May 2009), "The (not so) peculiar case of the Padua family", Monthly Notices of the Royal Astronomical Society, 395 (1): 358–377, Bibcode:2009MNRAS.395..358C, doi:10.1111/j.1365-2966.2009.14523.x.

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