253 Mathilde

Template:Short description Template:Use dmy dates Template:Good article {{#invoke:infobox|infoboxTemplate | class = vcard | titleclass = fn org | title = 253 Mathilde | image = {{#invoke:InfoboxImage|InfoboxImage|image=(253) mathilde crop.jpg|upright={{#if:||1.1}}|alt=}} | caption = Template:Longitem | headerstyle = {{#if:#D6D6D5|background-color:#D6D6D5|background-color:#E0CCFF}} | labelstyle = max-width:{{#if:||11em}}; | autoheaders = y

| header1 = Discovery<ref name="moore" />

| header10 = {{#if:|Designations|Designations}}

| header20 = Orbital characteristics{{#ifeq:|yes| (barycentric)}}<ref name="jpl">Unless otherwise noted, parameters are per: {{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

| data21 = | data22 = {{#if:31 July 2016 (JD 2457600.5) |Epoch 31 July 2016 (JD 2457600.5)}} | data23 = {{#if: | Uncertainty parameter {{{uncertainty}}}}} | label24 = Observation arc | data24 = | label25 = Earliest precovery date | data25 = | label26 = {{#switch:{{{apsis}}} |apsis|gee|barion|center|centre|(apsis)=Apo{{{apsis}}} |Ap{{#if:|{{{apsis}}}|helion}}}} | data26 = Template:Convert | label27 = Peri{{#if:|{{{apsis}}}|helion}} | data27 = Template:Convert | label28 = Peri{{#if:|{{{apsis}}}|apsis}} | data28 = | label29 = {{#switch:{{{apsis}}} |helion|astron=Ap{{{apsis}}} |Apo{{#if:|{{{apsis}}}|apsis}}}} | data29 = | label30 = Periastron | data30 = | label31 = Apoastron | data31 = | label32 = Template:Longitem | data32 = Template:Convert | label33 = Template:Longitem | data33 = | label34 = Eccentricity | data34 = 0.26492652 | label35 = Template:Longitem | data35 = 4.31 yr (1574.3 d) | label36 = Template:Longitem | data36 = | label37 = Template:Longitem | data37 = 17.98 km/s<ref>For semi-major axis a, orbital period T and eccentricity e, the average orbital speed is given by:

<math>\begin{align}

v_o & = \frac{2\pi a}{T}\left[1-\frac{e^2}{4}-\frac{3e^4}{64} - \dots \right] \\

   & = 18.31\ \mbox{km/s} \left[ 1 - 0.0177 - 0.00008 - \cdots \right] \\
   & \approx 17.98\ \mbox {km/s} \\

\end{align}\!\,</math> For the circumference of an ellipse, see: Template:Cite book</ref> | label38 = Template:Longitem | data38 = 170.584348° | label39 = Template:Longitem | data39 = | label40 = Inclination | data40 = 6.7427122° | label41 = Template:Longitem | data41 = | label42 = Template:Longitem | data42 = 179.58936° | label43 = Template:Longitem | data43 = | label44 = Template:Longitem | data44 = | label45 = Template:Longitem | data45 = 157.39642° | label46 = Template:Nowrap | data46 = | label47 = Satellite of | data47 = | label48 = Group | data48 = | label49 = {{#switch: |yes|true=Satellites |Known satellites}} | data49 = | label50 = Star | data50 = | label51 = Earth MOID | data51 = | label52 = Mercury MOID | data52 = | label53 = Venus MOID | data53 = | label54 = Mars MOID | data54 = | label55 = Jupiter MOID | data55 = | label56 = Saturn MOID | data56 = | label57 = Uranus MOID | data57 = | label58 = Neptune MOID | data58 = | label59 = T_Jupiter | data59 =

| header60 = Proper orbital elements

| label61 = Template:Longitem | data61 = {{#if: |{{{p_semimajor}}} AU}} | label62 = Template:Longitem | data62 = | label63 = Template:Longitem | data63 = | label64 = Template:Longitem | data64 = {{#if: |{{{p_mean_motion}}} deg Template:\yr}} | label65 = Template:Longitem | data65 = {{#if:|{{#expr:360/1 round 5}} yr
({{#expr:365.25*360/1 round 3}} d) }} | label66 = Template:Longitem | data66 = {{#if:|{{{perihelion_rate}}} arcsec Template:\yr }} | label67 = Template:Longitem | data67 = {{#if:|{{{node_rate}}} arcsec Template:\yr}}

| header70 = Template:Anchor{{#if:yes| Physical characteristics|Physical characteristics}}

| label71 = Dimensions | data71 = 52.8 km<ref name="jpl"/>
(66×48×46 km<ref name="icarus140"/>) | label72 = Template:Longitem | data72 = | label73 = Template:Longitem | data73 = | label74 = Template:Longitem | data74 = | label75 = Template:Longitem | data75 = | label76 = Flattening | data76 = | label77 = Circumference | data77 = | label78 = Template:Longitem | data78 = | label79 = Volume | data79 = | label80 = Mass | data80 = Template:Val<ref name="Yeomans 1997"/> | label81 = Template:Longitem | data81 = 1.3 g/cm³<ref name="Yeomans 1997"/> | label82 = Template:Longitem | data82 = Template:Gr m/s² | label83 = Template:Longitem | data83 = | label84 = Template:Longitem | data84 = 22.9 m/s | label85 = Template:Longitem | data85 = Template:Convert<ref name="jpl"/>
17.406 ± 0.010 d<ref>Template:Cite journal</ref>
(17 d 9 h 45 min) | label86 = Template:Longitem | data86 = | label87 = Template:Longitem | data87 = | label88 = Template:Longitem | data88 = | label89 = Template:Longitem | data89 = | label90 = Template:Longitem | data90 = | label91 = Template:Longitem | data91 = | label92 = Template:Longitem | data92 = | label93 = {{#if:yes |Template:Longitem |Albedo}} | data93 = Template:Val<ref name="jpl"/> | label94 = Temperature | data94 = ≈ 174<ref>For asteroid albedo α, semimajor axis a, solar luminosity <math>L_0</math>, Stefan–Boltzmann constant σ and the asteroid's infrared emissivity ε (≈ 0.9), the approximate mean temperature T is given by:

<math>\begin{align}

T & = \left ( \frac{(1 - \alpha) L_0}{\epsilon \sigma 16 \pi a^2} \right )^{\frac{1}{4

| data100 = {{#if:|

Surface temp.	min	mean	max
{{{temp_name1}}}
{{{temp_name2}}}
{{{temp_name3}}}
{{{temp_name4}}}

}}

| header110 = Atmosphere

| below = {{#if:||Template:Reflist }}

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 & = \left ( \frac{(1 - 0.0436) (3.827 \times 10^{26}\ \mbox{W})} {0.9 (5.670 \times 10^{-8}\ \mbox{W/m}^2\mbox{K}^4) 16 \cdot 3.142 (3.959 \times 10^{11}\ \mbox{m})^2} \right )^{\frac{1}{4}} \\
 & = 173.7\ \mbox{K}

\end{align}</math>

See: Template:Cite book</ref> K

| mean_motion=Template:Deg2DMS / day | observation_arc=130.38 yr (47622 d) | uncertainty=0 | moid=Template:Convert | jupiter_moid=Template:Convert | tisserand=3.331 }}

253 Mathilde is an asteroid in the intermediate asteroid belt, approximately 50 kilometers in diameter, that was discovered by Austrian astronomer Johann Palisa at Vienna Observatory on 12 November 1885. It has a relatively elliptical orbit that requires more than four years to circle the Sun. This tumbling asteroid has an unusually slow rate of rotation, requiring 17.4 days to complete a 360° revolution about its axis. It is a primitive C-type asteroid, which means the surface has a high proportion of carbon; giving it a dark surface that reflects only 4% of the light that falls on it.<ref name="flyby"/>

Mathilde was visited by the NEAR Shoemaker spacecraft during June 1997, on its way to asteroid 433 Eros. During the short flyby, the spacecraft imaged a hemisphere of the asteroid, revealing many large craters that had gouged out depressions in the surface. It was the first carbonaceous asteroid to be explored and, until 21 Lutetia was visited in 2010, it was the largest asteroid to be visited by a spacecraft.

Observation historyEdit

File:Animation of NEAR Shoemaker trajectory.gif

Animation of NEAR Shoemaker trajectory from 19 February 1996 to 12 February 2001.
Template:Legend2; Template:Legend2; Template:Legend2; Template:Legend2; Template:Legend2

In 1880, Johann Palisa, the director of the Austrian Naval Observatory Template:Obscode, was offered a position as an assistant at the newly completed Vienna Observatory. Although the job represented a demotion for Johann, it gave him access to the new Template:Convert refractor, the largest telescope in the world at that time. By this point Johann had already discovered 27 asteroids, and he would employ the Vienna Template:Convert and Template:Convert instruments to find an additional 94 asteroids before he retired.<ref> {{#invoke:citation/CS1|citation |CitationClass=web }} </ref>

Among his discoveries was the asteroid 253 Mathilde, found on 12 November 1885. The initial orbital elements of the asteroid were then computed by V. A. Lebeuf, another Austrian astronomer working at the Paris Observatory.<ref name="NEAR_press"/> The name of the asteroid was suggested by Lebeuf, after Mathilde, the wife of Moritz Loewy—who was the vice director of the observatory in Paris.<ref name="moore">Template:Cite book</ref><ref name="NEAR_press">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

In 1995, ground-based observations determined that Mathilde is a C-type asteroid. It was also found to have an unusually long period of rotation of 418 hours.<ref name="NEAR_press"/>

On 27 June 1997, the NEAR Shoemaker spacecraft passed within 1,212 km of Mathilde while moving at a velocity of 9.93 km/s. This close approach allowed the spacecraft to capture over 500 images of the surface,<ref name="flyby"/> and provided data for more accurate determinations of the asteroid's dimensions and mass (based on gravitational perturbation of the spacecraft).<ref name="Yeomans 1997"/> However, only one hemisphere of Mathilde was imaged during the fly-by.<ref name="aisr33">Template:Cite journal</ref> This was only the third asteroid to be imaged from a nearby distance, following 951 Gaspra and 243 Ida.

CharacteristicsEdit

File:253 Mathilde side.png

Damodar, a 20 km-wide crater on Mathilde

File:253 Mathilde Flyby.gif

Image sequence of Mathilde during NEAR Shoemaker's flyby

Mathilde is very dark, with an albedo comparable to fresh asphalt,<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> and is thought to share the same composition as CI1 or CM2 carbonaceous chondrite meteorites, with a surface dominated by phyllosilicate minerals.<ref>Template:Cite conference</ref> The asteroid has a number of extremely large craters, with the individual craters being named for coal fields and basins around the world.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> The two largest craters, Ishikari (29.3 km) and Karoo (33.4 km), are as wide as the asteroid's average radius.<ref name="icarus140">Template:Cite journal</ref> The impacts appear to have spalled large volumes off the asteroid, as suggested by the angular edges of the craters.<ref name="flyby">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Uniformity in brightness and colour were visible in the craters and there was no appearance of layering, so the asteroid's interior must be very homogeneous. There are indications of material movement along the downslope direction.<ref name="icarus140"/>

The density measured by NEAR Shoemaker, 1,300 kg/m³, is less than half that of a typical carbonaceous chondrite; this may indicate that the asteroid is very loosely packed rubble pile.<ref name="Yeomans 1997">Template:Cite journal</ref> The same is true of several C-type asteroids studied by ground-based telescopes equipped with adaptive optics systems (45 Eugenia, 90 Antiope, 87 Sylvia and 121 Hermione). Up to 50% of the interior volume of Mathilde consists of open space. However, the existence of a 20-km-long scarp may indicate that the asteroid does have some structural strength, so it could contain some large internal components.<ref name="aisr33"/> The low interior density is an inefficient transmitter of impact shock through the asteroid, which also helps to preserve the surface features to a high degree.<ref name="icarus140"/>

Mathilde's orbit is eccentric, taking it to the outer reaches of the belt. Nonetheless, the orbit lies entirely between the orbits of Mars and Jupiter; it does not cross the planetary orbits. It also has one of the slowest rotation periods of the known asteroids—most asteroids have a rotation period in the range of 2–24 hours.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Because of the slow rotation rate, NEAR Shoemaker was only able to photograph 60% of the asteroid's surface. The slow rate of rotation may be accounted for by a satellite orbiting the asteroid, but a search of the NEAR images revealed none larger than 10 km in diameter out to 20 times the radius of Mathilde.<ref>Template:Cite journal</ref>

ReferencesEdit

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External linksEdit

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253 Mathilde

Contents

Observation historyEdit

CharacteristicsEdit

See alsoEdit

ReferencesEdit

External linksEdit