7803 Adachi

{{Short description|Stony Agnia asteroid}}

{{Use dmy dates|date=March 2018}}

{{Infobox planet

| minorplanet = yes

| name = 7803 Adachi

| background = #D6D6D6

| image =

| image_size =

| caption =

| discovery_ref =  

| discovered = 4 March 1997

| discoverer = T. Kobayashi

| discovery_site = Ōizumi Obs.

| mpc_name = (7803) Adachi

| alt_names = {{mp|1997 EW|2}}{{·}}{{mp|1973 AA|3}}
{{mp|1976 UY|17}}{{·}}{{mp|1978 EM|1}}
{{mp|1992 CF|2}}

| named_after = Makoto Adachi 
{{small|(amateur astronomer)}}

| mp_category = main-belt{{·}}{{small|(middle)}}
Agnia

| orbit_ref =  

| epoch = 23 March 2018 (JD 2458200.5)

| uncertainty = 0

| observation_arc = 63.96 yr (23,363 d)

| aphelion = 2.9253 AU

| perihelion = 2.6459 AU

| semimajor = 2.7856 AU

| eccentricity = 0.0502

| period = 4.65 yr (1,698 d)

| mean_anomaly = 239.11°

| mean_motion = {{Deg2DMS|0.2120|sup=ms}} / day

| inclination = 4.9969°

| asc_node = 110.63°

| arg_peri = 8.8759°

| dimensions = {{val|6.359|0.129|ul=km}}
{{val|10.31|u=km}} {{small|(calculated)}}

| rotation = {{val|5.1966|0.0082|ul=h}}

| albedo = 0.057 {{small|(assumed)}}
{{val|0.251|0.055}}

| spectral_type = S{{·}}C {{small|(generic)}}

| abs_magnitude = 13.1{{·}}{{val|13.212|0.005}} {{small|(R)}}{{·}}13.3{{·}}{{val|13.65|0.27}}{{·}}13.66

}}

7803 Adachi, provisional designation {{mp|1997 EW|2}}, is a stony Agnia asteroid from the middle region of the asteroid belt, approximately {{convert|6.4|km|mi|abbr=off|sigfig=1|sp=us}} in diameter. The asteroid was discovered on 4 March 1997, by Japanese amateur astronomer Takao Kobayashi at the Ōizumi Observatory in central Japan. It was named for Japanese amateur astronomer Makoto Adachi. The S-type asteroid has a rotation period of 5.2 hours.

Orbit and classification

Adachi is a member of the Agnia family ({{small|514}}), a very large family of stony asteroids with more than 2000 known members. They most likely formed from the breakup of a basalt object, which in turn was spawned from a larger parent body that underwent igneous differentiation. The family's parent body and namesake is the asteroid 847 Agnia.

It orbits the Sun in the central asteroid belt at a distance of 2.6–2.9 AU once every 4 years and 8 months (1,698 days; semi-major axis of 2.79 AU). Its orbit has an eccentricity of 0.05 and an inclination of 5° with respect to the ecliptic. The first precovery was taken at the U.S. Palomar Observatory in 1953, extending the asteroid's observation arc by 44 years prior to it discovery.

Physical characteristics

Adachi has been characterized as a stony S-type asteroid by Pan-STARRS photometric survey, which agrees with the Agnia family's overall spectral type. {{rp|23}}

= Diameter and albedo =

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Adachi measures 6.359 kilometers in diameter and its surface has an albedo between 0.251 and 0.2513. The Collaborative Asteroid Lightcurve Link assumes a generic, carbonaceous albedo of 0.057 for all minor planets with a semi-major axis of more than 2.7 AU, and consequently calculates a larger diameter of 10.31 kilometers using an absolute magnitude of 13.66.

= Rotation period =

In August 2013, a rotational lightcurve of Adachi was obtained through photometric observations at the Palomar Transient Factory in California. It showed a period of {{val|5.1966}} hours with a brightness variation of 0.31 magnitude ({{small|U=2}}).

Naming

This minor planet was named after Makoto Adachi (born 1953), Japanese amateur astronomer and elementary school teacher from Kyoto. He is the director of the Oriental Astronomical Association and a long-time direct observer of the Solar System's planets, especially Jupiter. The approved naming citation was published by the Minor Planet Center on 6 August 2003 {{small|(M.P.C. 49279)}}.

References

{{reflist|30em|refs=

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|type = 2017-09-27 last obs.

|title = JPL Small-Body Database Browser: 7803 Adachi (1997 EW2)

|url = https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2007803

|publisher = Jet Propulsion Laboratory

|access-date = 8 March 2018}}

{{cite web

|title = 7803 Adachi (1997 EW2)

|work = Minor Planet Center

|url = https://www.minorplanetcenter.net/db_search/show_object?object_id=7803

|access-date = 28 April 2016}}

{{cite web

|title = MPC/MPO/MPS Archive

|work = Minor Planet Center

|url = https://www.minorplanetcenter.net/iau/ECS/MPCArchive/MPCArchive_TBL.html

|access-date = 28 April 2016}}

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|access-date= 8 March 2018

}}

{{cite web

|title = LCDB Data for (7803) Adachi

|publisher = Asteroid Lightcurve Database (LCDB)

|url = http://www.minorplanet.info/PHP/generateOneAsteroidInfo.php?AstInfo=7803%7CAdachi

|access-date = 28 April 2016}}

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{{cite journal

|display-authors = 6

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}}