21795 Masi (provisional designation 1999 SN9) is a Nysian asteroid from the inner regions of the asteroid belt, approximately 3 kilometers (2 miles) in diameter. It was discovered on 29 September 1999, by Italian amateur astronomer Franco Mallia at the Campo Catino Astronomical Observatory in Lazio, Italy.[1] The likely S-type asteroid has a rotation period of 13.86 hours.[4] It was named for Italian astronomer Gianluca Masi.[1]
| Discovery [1] | |
|---|---|
| Discovered by | F. Mallia |
| Discovery site | Campo Catino Obs. |
| Discovery date | 29 September 1999 |
| Designations | |
| (21795) Masi | |
Named after | Gianluca Masi [1] (Italian astronomer) |
| 1999 SN9 · 1988 UE 1993 BZ1 | |
| main-belt [1][2] · (inner) Nysa [3] | |
| Orbital characteristics [2] | |
| Epoch 23 March 2018 (JD 2458200.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 64.45 yr (23,541 d) |
| Aphelion | 2.8409 AU |
| Perihelion | 1.9222 AU |
| 2.3815 AU | |
| Eccentricity | 0.1929 |
| 3.68 yr (1,342 d) | |
| 337.35° | |
| 0° 16m 5.52s / day | |
| Inclination | 1.8376° |
| 337.09° | |
| 81.681° | |
| Physical characteristics | |
Mean diameter | 2.45 km (calculated)[4] 3.150±0.164 km[5][6] |
| 13.862±0.0121 h[7] | |
| 0.20 (assumed)[4] 0.235±0.037[5][6] | |
| S (assumed)[4] | |
| 14.7[6] 14.9[2] 14.970±0.004 (R)[7] 15.41±0.14[8] 15.42[4] | |
Orbit and classification edit
Masi is member of the Nysa family (405),[3] located in the Nysa–Polana complex and one of the largest asteroid families of the asteroid belt, named after 44 Nysa.[9] It orbits the Sun in the inner main-belt at a distance of 1.9–2.8 AU once every 3 years and 8 months (1,342 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.19 and an inclination of 2° with respect to the ecliptic.[2] The body's observation arc begins with a precovery published by the Digitized Sky Survey and taken at the Palomar Observatory in April 1954, more than 45 years prior to its official discovery observation at Campo Catino.[1]
Physical characteristics edit
Masi is an assumed, stony S-type asteroid,[4] which is also the overall spectral type for members of the Nysa family of asteroids.[9]: 23
Rotation period edit
In September 2010, a rotational lightcurve of Masi was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 13.862 hours with a relatively high brightness amplitude of 0.68 magnitude (U=2).[7]
Diameter and albedo edit
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Masi measures 3.150 kilometers in diameter and its surface has an albedo of 0.235,[5][6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20, and calculates a diameter of 2.45 kilometers based on an absolute magnitude of 15.42.[4]
Naming edit
This minor planet was named after Italian astrophysicist and astronomer, Gianluca Masi (born 1972), a researcher and discoverer of minor planets and variable stars, who became an avid amateur astronomer when he was 8 years old.[1] The official naming citation was published by the Minor Planet Center on 9 May 2001 (M.P.C. 42679).[10]
References edit
- ^ a b c d e f g "21795 Masi (1999 SN9)". Minor Planet Center. Retrieved 29 May 2018.
- ^ a b c d "JPL Small-Body Database Browser: 21795 Masi (1999 SN9)" (2017-09-27 last obs.). Jet Propulsion Laboratory. Retrieved 29 May 2018.
- ^ a b "Asteroid 21795 Masi". Small Bodies Data Ferret. Retrieved 29 May 2018.
- ^ a b c d e f g "LCDB Data for (21795) Masi". Asteroid Lightcurve Database (LCDB). Retrieved 29 May 2018.
- ^ a b c Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
- ^ a b c d 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. (catalog)
- ^ a b c Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.
- ^ 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.
- ^ a b Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
- ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 29 May 2018.
External links edit
- Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
- Dictionary of Minor Planet Names, Google books
- Discovery Circumstances: Numbered Minor Planets (20001)-(25000) – Minor Planet Center
- 21795 Masi at AstDyS-2, Asteroids—Dynamic Site
- 21795 Masi at the JPL Small-Body Database
