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1025 Riema
Discovery [1]
Discovered by K. Reinmuth
Discovery site Heidelberg Obs.
Discovery date12 August 1923
Designations
(1025) Riema
Named after
Johannes Riem
(German astronomer) [2]
1923 NX · A923 QA
main-belt · ( inner) [1] · Hungaria [3] [4]
Orbital characteristics [1]
Epoch 4 September 2017 ( JD 2458000.5)
Uncertainty parameter 0
Observation arc93.81 yr (34,264 days)
Aphelion2.0572 AU
Perihelion1.9009 AU
1.9790 AU
Eccentricity0.0395
2.78 yr (1,017 days)
102.31 °
0° 21m 14.4s / day
Inclination26.863°
163.39°
349.06°
Physical characteristics
Dimensions4.605±0.171 km [5]
5.48 km (derived) [3]
3.566±0.005 h [6]
3.578±0.002 h [a] [b]
3.580±0.005 h [7]
3.581±0.002 h [8] [c]
3.581±0.001 h [9] [b]
3.588±0.002 h [10] [b]
6.557±0.001 h [11]
1.000±0.000 [5]
0.166±0.036 [12]
0.40 (assumed) [3]
E ( Tholen), Xe ( SMASS)
M [13] · Xe [3]
B–V = 0.714 [1]
U–B = 0.294 [1]
V–R = 0.440±0.010 [11]
12.30 [5] · 12.5 [1]
12.57±0.28 [14] · 12.92±0.04 [3] [15] [16]

1025 Riema, provisional designation 1923 NX, is a bright Hungaria asteroid from the innermost regions of the asteroid belt, approximately 5 kilometers in diameter. It was discovered on 12 August 1923, by German astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany. [17] The asteroid was named after ARI astronomer Johannes Riem. [2]

Orbit and classification

Riema is a member of the Hungaria family, which form the innermost dense concentration of asteroids in the Solar System. It orbits the Sun at a distance of 1.9–2.1  AU once every 2 years and 9 months (1,017 days). Its orbit has an eccentricity of 0.04 and an inclination of 27 ° with respect to the ecliptic. [1] The asteroid's observation arc begins at Heidelberg, four nights after its official discovery observation. [17]

Physical characteristics

In the Tholen classification, Riema is a bright E-type asteroid. In the SMASS taxonomy, it has been classified as a Xe-type, which transitions from the E to the X-types. [1] In addition, the asteroid has also been polarimetrically characterized as a metallic M-type asteroid. [13]

Lightcurves

In August 2001, a first rotational lightcurve of Riema was obtained from photometric observations by Ukrainian astronomers at Kharkiv ( 101) and Simeiz ( 094). Lightcurve analysis gave a rotation period of 6.557 hours with a brightness variation of 0.25 magnitude ( U=2). [11]

The Ukrainian team also determined the body's poles and axis-ratios. They found a spin axis of (141.0°, 11.0°) and (321.0.0°, −13.0°) in ecliptic coordinates (λ, β), as well as a semi-axis ratio of 3.41 (a/b) and 1.16 (b/c) for the three-axial ellipsoid model ( Q=2). [11]

Between 2003 and 2017, several additional lightcurves were obtained by American photometrists Robert Stephens and Brian Warner at the Santana Observatory ( 646), the Palmer Divide Observatory ( 716) and the Palmer Divide Station ( U82), respectively. The constructed lightcurve gave a shorter period for Riema between 3.566 and 3.588 hours with a low amplitude of 0.06 to 0.19 magnitude ( U=2/2/2+/2+/3/3). [7] [8] [9] [10] [a] [c] [b]

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Riema measures 4.605 kilometers in diameter and its surface has an outstandingly high albedo of 1.000. [5] The Collaborative Asteroid Lightcurve Link assumes an albedo for E-type Hungaria asteroids of 0.40 – taken from 434 Hungaria, the family's largest member and namesake – and derives a diameter of 5.48 kilometers based on an absolute magnitude of 12.92. [3]

Naming

This minor planet was named after Johannes Karl Richard Riem (1868–1945), a German astronomer at the Astronomisches Rechen-Institut (ARI) in Berlin. The name was suggested by ARI. The official naming citation was published by Paul Herget in The Names of the Minor Planets in 1955 ( H 98). [2]

Notes

  1. ^ a b Warner (2017) web: rotation period 3.578±0.002 hours with a brightness amplitude of 0.06 mag. Summary figures for (1025) Riema at Collaborative Asteroid Lightcurve Link (CALL)
  2. ^ a b c d Lightcurve plots by B. D. Warner at the Palmer Divide Station in California: (2014), (2015) and (2017)
  3. ^ a b Lightcurve plot of 1025 Riema with a period of 3.581±0.002 hours, Palmer Divide Observatory, Colorado, B. D. Warner (2012)

References

  1. ^ a b c d e f g h "JPL Small-Body Database Browser: 1025 Riema (1923 NX)" (2017-06-04 last obs.). Jet Propulsion Laboratory. Retrieved 6 July 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). "(1025) Riema". Dictionary of Minor Planet Names – (1025) Riema. Springer Berlin Heidelberg. p. 88. doi: 10.1007/978-3-540-29925-7_1026. ISBN  978-3-540-00238-3.
  3. ^ a b c d e f "LCDB Data for (1025) Riema". Asteroid Lightcurve Database (LCDB). Retrieved 6 July 2017.
  4. ^ Spratt, Christopher E. (April 1990). "The Hungaria group of minor planets". Journal of the Royal Astronomical Society of Canada. 84: 123–131. Bibcode: 1990JRASC..84..123S. ISSN  0035-872X. Retrieved 6 July 2017.
  5. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv: 1209.5794. Bibcode: 2012ApJ...759L...8M. doi: 10.1088/2041-8205/759/1/L8. Retrieved 6 July 2017.
  6. ^ Warner, Brian D. (October 2009). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2009 March-June". The Minor Planet Bulletin. 36 (4): 172–176. Bibcode: 2009MPBu...36..172W. ISSN  1052-8091. Retrieved 6 July 2017.
  7. ^ a b Stephens, Robert D. (December 2003). "Photometry of 628 Christine, 754 Malabar, 815 Coppelia, and 1025 Riema". The Minor Planet Bulletin. 30 (4): 69–70. Bibcode: 2003MPBu...30...69S. ISSN  1052-8091. Retrieved 6 July 2017.
  8. ^ a b Warner, Brian D. (January 2013). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2012 June - September". The Minor Planet Bulletin. 40 (1): 26–29. Bibcode: 2013MPBu...40...26W. ISSN  1052-8091. Retrieved 6 July 2017.
  9. ^ a b Warner, Brian D. (January 2016). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2015 June-September". The Minor Planet Bulletin. 43 (1): 57–65. Bibcode: 2016MPBu...43...57W. ISSN  1052-8091. Retrieved 6 July 2017.
  10. ^ a b Warner, Brian D. (July 2014). "Asteroid Lightcurve Analysis at CS3-Palmer Divide Station: 2014 January-March". The Minor Planet Bulletin. 41 (3): 144–155. Bibcode: 2014MPBu...41..144W. ISSN  1052-8091. Retrieved 6 July 2017.
  11. ^ a b c d Shevchenko, V. G.; Krugly, Yu. N.; Chiorny, V. G.; Belskaya, I. N.; Gaftonyuk, N. M. (August 2003). "Rotation and photometric properties of E-type asteroids". Planetary and Space Science. 51 (9–10): 525–532. Bibcode: 2003P&SS...51..525S. doi: 10.1016/S0032-0633(03)00076-X. Retrieved 6 July 2017.
  12. ^ Gil-Hutton, R.; Lazzaro, D.; Benavidez, P. (June 2007). "Polarimetric observations of Hungaria asteroids" (PDF). Astronomy and Astrophysics. 468 (3): 1109–1114. Bibcode: 2007A&A...468.1109G. doi: 10.1051/0004-6361:20077178. Retrieved 6 July 2017.
  13. ^ a b Belskaya, I. N.; Fornasier, S.; Tozzi, G. P.; Gil-Hutton, R.; Cellino, A.; Antonyuk, K.; et al. (March 2017). "Refining the asteroid taxonomy by polarimetric observations". Icarus. 284: 30–42. Bibcode: 2017Icar..284...30B. doi: 10.1016/j.icarus.2016.11.003. Retrieved 6 July 2017.
  14. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv: 1506.00762. Bibcode: 2015Icar..261...34V. doi: 10.1016/j.icarus.2015.08.007. Retrieved 6 July 2017.
  15. ^ Wisniewski, W. Z.; Michalowski, T. M.; Harris, A. W.; McMillan, R. S. (March 1995). "Photoelectric Observations of 125 Asteroids". Abstracts of the Lunar and Planetary Science Conference. 26: 1511. Bibcode: 1995LPI....26.1511W. Retrieved 6 July 2017.
  16. ^ Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode: 2012Icar..221..365P. doi: 10.1016/j.icarus.2012.07.026. Retrieved 6 July 2017.
  17. ^ a b "1025 Riema (1923 NX)". Minor Planet Center. Retrieved 6 July 2017.

External links

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