Asteroid 298 Baptistina (apparent magnitude 15.2) near a mag 15.3 star.
|Discovered by||Auguste Charlois|
|Discovery date||September 9, 1890|
|Minor planet category||Main belt,
|Epoch 30 January 2005 (JD 2453400.5)|
|Aphelion||2.481 AU (371.081 Gm)|
|Perihelion||2.047 AU (306.285 Gm)|
|Semi-major axis||2.264 AU (338.683 Gm)|
|Orbital period||3.41 a (1244.205 d)|
|Average orbital speed||19.8 km/s|
|Longitude of ascending node||8.346°|
|Argument of perihelion||134.492°|
|Rotation period||16.23±0.02 hours|
|Absolute magnitude (H)||11.0|
298 Baptistina is an asteroid orbiting in the asteroid belt. It is the namesake of the Baptistina family. It was discovered on September 9, 1890, by Auguste Charlois of Nice. The reason for its name is unknown. It measures from about 13 to 30 kilometres (8 to 19 mi) in diameter. Although it has an orbit similar to the Flora family asteroids, Baptistina was found to be an unrelated interloper. 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.
Extinction event theory
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. This led to a suggestion that one fragment from the event may have eventually become the K–T impactor believed to have caused the Cretaceous–Paleogene extinction event that brought about the extinction of the dinosaurs 66 million years ago.
Concerns were originally raised about this theory, in part because very few solid observational constraints exist of the asteroid or family. Recently, it was discovered that Baptistina does not share the same chemical signature as the source of the Cretaceous–Paleogene boundary (K–T boundary). While this finding made the link between the Baptistina family and K–T impactor more difficult to accept, it did not preclude the possibility.
However, 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, these data mean 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. "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.
- Reddy V., et al. (2008). Composition of 298 Baptistina: Implications for K–T Impactor Link, Asteroids, Comets, Meteors conference.
- Majaess D., Higgins D., Molnar L., Haegert M., Lane D., Turner D., Nielsen I. (2008). New Constraints on the Asteroid 298 Baptistina, the Alleged Family Member of the K/T Impactor, accepted for publication in the JRASC
- Lutz D. Schmadel, Dictionary of Minor Planet Names, p.41.
- M. Florczak et al. A Visible Spectroscopic Survey of the Flora Clan, Icarus Vol. 133, p. 233 (1998)
- Bottke W., Vokrouhlický D., Nesvorný D. (2007) An asteroid breakup 160 Myr ago as the probable source of the K/T impactor. Nature 449, 48-53
- Plotner, Tammy (2011). "Did Asteroid Baptistina Kill the Dinosaurs? Think other WISE...". Universe Today. Retrieved 2011-09-19.
- "Asteroid didn't do it - so who killed the dinosaurs? NASA rules out Baptistina theory". News.com.au / Fox. 2011. Retrieved 2012-02-29.