2608 Seneca

2608 Seneca, provisional designation 1978 DA, is a stony asteroid and sub-kilometer near-Earth object of the Amor group, approximately 0.9 kilometers in diameter. It was discovered on 17 February 1978, by German astronomer Hans-Emil Schuster at ESO's La Silla Observatory in northern Chile, and named after Roman philosopher Seneca.^[3][4]

2608 Seneca

Discovery [1]
Discovered by	H.-E. Schuster
Discovery site	La Silla Obs.
Discovery date	17 February 1978
Designations
MPC designation	(2608) Seneca
Pronunciation	/ˈsɛnɪkə/ SEN-ik-ə[2]
Named after	Seneca the Younger (Roman philosopher)[3]
Alternative designations	1978 DA
Minor planet category	NEO · Amor [1][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 1
Observation arc	38.92 yr (14,217 days)
Aphelion	3.9532 AU
Perihelion	1.0777 AU
Semi-major axis	2.5154 AU
Eccentricity	0.5716
Orbital period (sidereal)	3.99 yr (1,457 days)
Mean anomaly	353.12°
Mean motion	0° 14m 49.56s / day
Inclination	14.682°
Longitude of ascending node	167.37°
Argument of perihelion	37.350°
Earth MOID	0.1321 AU · 51.5 LD
Physical characteristics
Dimensions	0.9 km[1][5][6] 1.0±0.3[6]
Synodic rotation period	8 h[6]
Geometric albedo	0.15±0.03[6] 0.20 (derived)[5] 0.21[1]
Spectral type	Tholen = S [1] · S [5] B–V = 0.826[1] U–B = 0.454[1]
Absolute magnitude (H)	17.52[1] · 17.59[5][7] · 17.73[6]

Orbit

Seneca orbits the Sun at a distance of 1.1–4.0 AU once every 3 years and 12 months (1,457 days). Its orbit has an eccentricity of 0.57 and an inclination of 15° with respect to the ecliptic.^[1]

The body's observation arc begins with its official discovery observation in 1978, as no precoveries were taken, and no prior identifications were made.^[4]

Close approaches

Seneca has an Earth minimum orbital intersection distance of 0.1321 AU (19,800,000 km), which corresponds to 51.5 lunar distances.^[1] On 22 March 2062, it will pass 0.254 AU (38,000,000 km) from the Earth.^[8]

Physical characteristics

In the Tholen taxonomy, Seneca is a stony S-type asteroid.^[1]

Photometry

In March 1978, a photometric observations taken by Degewij and Lebofsky at the Lunar and Planetary Laboratory, Arizona, using a 154-cm reflector, gave a rotational lightcurve with a rotation period of 8 hours and a brightness amplitude of 0.4 (0.5) magnitude (U=2).^[6]

Radiometry

In addition, radiometric observations by L. and M. Lebofsky with the 71-cm reflector gave a mean-diameter of 1.0±0.3 kilometers and albedo of 0.15±0.03.^[6]

Diameter and albedo

The Minor Planet Center classifies Seneca as an object larger than 1 kilometer ("1+ KM Near-Earth Object"),^[4] while Collaborative Asteroid Lightcurve Link derives an albedo of 0.20 and a diameter of 0.9 kilometers based on an absolute magnitude of 17.59.^[5] In 1994, astronomer Tom Gehrels published a diameter of 0.9 kilometers with an albedo of 0.21 in his Hazards Due to Comets and Asteroids.^[1]

Naming

This minor planet was named after Roman philosopher and statesman Lucius Annaeus Seneca (c. 4 BC – AD 65), also known as "Seneca the Younger" or simply "Seneca".^[3] The approved naming citation was published by the Minor Planet Center on 8 April 1982 (M.P.C. 6835).^[9] The lunar crater Seneca was also named in his honor.^[3]

References

1. "JPL Small-Body Database Browser: 2608 Seneca (1978 DA)" (2017-01-20 last obs.). Jet Propulsion Laboratory. Retrieved 3 July 2017.
2. "Seneca". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
3. Schmadel, Lutz D. (2007). "(2608) Seneca". Dictionary of Minor Planet Names – (2608) Seneca. Springer Berlin Heidelberg. p. 213. doi:10.1007/978-3-540-29925-7_2609. ISBN 978-3-540-00238-3.
4. "2608 Seneca (1978 DA)". Minor Planet Center. Retrieved 26 March 2017.
5. "LCDB Data for (2608) Seneca". Asteroid Lightcurve Database (LCDB). Retrieved 26 March 2017.
6. Degewij, J.; Lebofsky, L.; Lebofsky, M. (March 1978). "1978 CA and 1978 DA". IAU Circ. 3193 (3193): 1. Bibcode:1978IAUC.3193....1D. Retrieved 26 March 2017.
7. Schuster, H. E.; Surdej, A.; Surdej, J. (September 1979). "Photoelectric observations of two unusual asteroids - 1978 CA and 1978 DA". Astronomy and Astrophysics Supplement Series. 37: 483–486. Bibcode:1979A&AS...37..483S. Retrieved 26 March 2017.
8. "JPL Close-Approach Data: 2608 Seneca (1978 DA)" (2010-08-19 last obs). Retrieved 15 April 2016.
9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 26 March 2017.

External links

• Hazards Due to Comets and Asteroids, Tom Gehrels (1994/5)
• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• 2608 Seneca at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• 2608 Seneca at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• 2608 Seneca at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters