1615 Bardwell

1615 Bardwell, provisional designation 1950 BW, is a rare-type Themistian asteroid from the outer region of the asteroid belt, approximately 27 kilometers in diameter. It was discovered on 28 January 1950, by IU's Indiana Asteroid Program at Goethe Link Observatory near Brooklyn, Indiana, United States.[11] It is named for American astronomer Conrad Bardwell.[2]

1615 Bardwell
Discovery[1]
Discovered byIndiana University
(Indiana Asteroid Program)
Discovery siteGoethe Link Obs.
Discovery date28 January 1950
Designations
(1615) Bardwell
Named after
Conrad Bardwell (astronomer)[2]
1950 BW · 1926 TO
1937 TJ · 1948 RB1
1948 RH1 · 1948 TG
main-belt · Themis[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc90.49 yr (33,053 days)
Aphelion3.6887 AU
Perihelion2.5664 AU
3.1275 AU
Eccentricity0.1794
5.53 yr (2,020 days)
169.71°
0° 10m 41.52s / day
Inclination1.6901°
152.55°
252.97°
Physical characteristics
Dimensions21.92±5.97 km[4]
25.01±1.49 km[5]
27.78±1.6 km (IRAS:5)[6]
28.8±2.9 km[7]
29.139±0.148 km[8]
31±3 km[9]
31.579±0.250 km[10]
18 h[lower-alpha 1]
0.0497±0.0192[10]
0.05±0.01[9]
0.060±0.010[8][7]
0.0642±0.008 (IRAS:5)[6]
0.079±0.015[5]
0.09±0.06[4]
Tholen = B[1] · B[3]
B–V = 0.692[1]
U–B = 0.329[1]
11.38[1][3][5][6][7][9][10] · 11.46[4]

    Orbit and classification

    Bardwell is a member of the Themis family, a dynamical family of outer-belt asteroids with nearly coplanar ecliptical orbits. It orbits the Sun at a distance of 2.6–3.7 AU once every 5 years and 6 months (2,020 days). Its orbit has an eccentricity of 0.18 and an inclination of 2° with respect to the ecliptic.[1]

    Its orbit has an eccentricity of 0.18 and an inclination of 2° with respect to the ecliptic.[1] It was first identified as 1926 TO at Simeiz Observatory in 1926, extending the body's observation arc by 24 years prior to its official discovery observation.[11]

    Naming

    This minor planet was named for Conrad M. Bardwell (1926–2010), who was a research associate at the Cincinnati Observatory and later associate director of the Minor Planet Center in Cambridge, Massachusetts, United States. Bardwell successfully established numerous identifications from observations in widely separated oppositions and provided observers with reliable data of orbital elements.[2] The official naming citation was published by the Minor Planet Center on 15 June 1974 (M.P.C. 3643).[12]

    Physical characteristics

    In the Tholen taxonomy, Bardwell is a blueish B-type asteroid, a rare subtype of the abundant carbonaceous C-types found in the outer belt. The spectra of B-type bodies show a broad absorption feature at one micron wavelength that is associated with the presence of magnetite and is what gives the asteroid its blue tint.[13] There are only a few dozens asteroids of this type known to exist.[14]

    Rotation period

    In the late 1970s, a rotational lightcurve of Bardwell was obtained by American astronomer Edward Tedesco. It gave a provisional rotation period of 18 hours with a change in brightness of 0.2 magnitude (U=1).[lower-alpha 1] As of 2017, no other photometric analysis of Bardwell has been made.

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Bardwell measures between 21.92 and 31.58 kilometers in diameter, and its surface has an albedo between 0.049 and 0.09.[4][6][7][8][10] The Collaborative Asteroid Lightcurve Link agrees with the results obtained by IRAS, that is, an albedo of 0.0642 and a diameter of 27.78 kilometers based on an absolute magnitude of 11.38.[3]

    Notes
    1. Tedesco, E.F. (1979) PhD Dissertation, New. Mex. State Univ. 280pp.; Rotation period of 18 hours with a brightness amplitude of 0.2. Summary figures at Asteroid Lightcurve Database for (1615) Bardwell

    References
    1. "JPL Small-Body Database Browser: 1615 Bardwell (1950 BW)" (2017-03-30 last obs.). Jet Propulsion Laboratory. Retrieved 4 June 2017.
    2. Schmadel, Lutz D. (2007). "(1615) Bardwell". Dictionary of Minor Planet Names – (1615) Bardwell. Springer Berlin Heidelberg. p. 128. doi:10.1007/978-3-540-29925-7_1616. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (1615) Bardwell". Asteroid Lightcurve Database (LCDB). Retrieved 28 December 2016.
    4. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 28 December 2016.
    5. 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 28 December 2016.
    6. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 17 October 2019.
    7. Alí-Lagoa, V.; Licandro, J.; Gil-Hutton, R.; Cañ; ada-Assandri, M.; Delbo', M.; et al. (June 2016). "Differences between the Pallas collisional family and similarly sized B-type asteroids". Astronomy and Astrophysics. 591: 11. Bibcode:2016A&A...591A..14A. doi:10.1051/0004-6361/201527660. hdl:11336/63614. Retrieved 28 December 2016.
    8. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 28 December 2016.
    9. Alí-Lagoa, V.; de León, J.; Licandro, J.; Delbó, M.; Campins, H.; Pinilla-Alonso, N.; et al. (June 2013). "Physical properties of B-type asteroids from WISE data". Astronomy and Astrophysics. 554: 16. arXiv:1303.5487. Bibcode:2013A&A...554A..71A. doi:10.1051/0004-6361/201220680. Retrieved 28 December 2016.
    10. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    11. "1615 Bardwell (1950 BW)". Minor Planet Center. Retrieved 28 December 2016.
    12. Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.
    13. Yang, Bin; Jewitt, David (September 2010). "Identification of Magnetite in B-type Asteroids". The Astronomical Journal. 140 (3): 692–698. arXiv:1006.5110. Bibcode:2010AJ....140..692Y. doi:10.1088/0004-6256/140/3/692. Retrieved 28 December 2016.
    14. "JPL db query spectral type = B (SMASSII and/or Tholen)". JPL Small-Body Database. Jet Propulsion Laboratory. Retrieved 15 November 2015.

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