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Asteroid 298 Baptistina (apparent magnitude 15.2) near a mag 15.3 star.
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Discovery
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| Discovered by | Auguste Charlois |
| Discovery date | September 9, 1890 |
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Designations
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| Minor planet category |
Main belt |
| Epoch 30 January 2005 (JD 2453400.5) | |
| Aphelion | 371.081 Gm (2.481 AU) |
| Perihelion | 306.285 Gm (2.047 AU) |
| Semi-major axis | 338.683 Gm (2.264 AU) |
| Eccentricity | 0.096 |
| Orbital period | 1244.205 d (3.41 a) |
| Average orbital speed | 19.8 km/s |
| Mean anomaly | 74.903° |
| Inclination | 6.285° |
| Longitude of ascending node | 8.346° |
| Argument of perihelion | 134.492° |
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Physical characteristics
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| Dimensions | 13 - 30 km[1][2] |
| Mass | unknown |
| Mean density | unknown |
| Equatorial surface gravity | unknown |
| Escape velocity | unknown |
| Rotation period | 16.23±0.02 hours[2] |
| Albedo | unknown |
| Temperature | unknown |
| Spectral type | X-type |
| Absolute magnitude (H) | 11.0 |
298 Baptistina is a main belt asteroid, part of the Baptistina family of asteroids. It was discovered on September 9, 1890 by Auguste Charlois of Nice. The reason for its name is unknown.[3] It measures around 13–30 km in diameter. Although it has an orbit similar to the Flora family asteroids, Baptistina was found to be an unrelated interloper.[4] It was considered the possible source of the impactor said to have caused the extinction of the dinosaurs, a possibility ruled out by the Wide-field Infrared Survey Explorer in 2011.
In 2007, a study by William F. Bottke, David Vokrouhlický and David Nesvorný proposed that several known asteroids can be regarded as the "Baptistina family" because they share similar orbital elements. Further, the study argues that the family is the remnant of a 170 km (110 mi) parent asteroid that was destroyed in a collision with a smaller body some 80 million years ago, with Baptistina itself being the largest remnant. Until recently, it was believed that this collision event occurred 160 million years ago, but NASA's WISE (Wide-Field Infrared Survey Explorer), used to determined the age of things in space, revealed that this collision event occurred more recently, some 80 million years ago. It is suggested that a fragment from this event eventually became the K/T impactor believed to have caused the Cretaceous–Tertiary extinction event that brought about the extinction of the dinosaurs 65 million years ago.[5] However, NASA's recent discovery cuts the time for the remnants to reach earth to 15 million years; too little time for this collision to have caused the mass extinction of the dinosaurs; "as a result of the WISE science team's investigation, the demise of the dinosaurs remains in the cold case files," said Lindley Johnson, program executive for the Near Earth Object (NEO) Observation Program. [1]
Concerns have been raised about this theory, in part because very few solid observational constraints exist of the asteroid or family.[2] Indeed, it was recently discovered that Baptistina does not share the same chemical signature as the source of the K–T boundary.[1] However, while this finding may make the link between the Baptistina family and K-T impactor more difficult to substantiate, it does not preclude the possibility.[1]
In 2011, data from the Wide-field Infrared Survey Explorer revised the date of the proposed collision which broke-up the Baptistina parent asteroid to about 80 million years ago. If correct, this data means it is very unlikely that the K/T impactor was part of this family of asteroids, as it typically takes many tens of millions of years for an asteroid to reach a resonance with Earth and then collide, much more than the 15 million between this breakup and the collision of the K/T impactor.[6]
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