TheBaptistina family (FIN:403) is anasteroid family of more than 2500 members that was probably produced by the breakup of anasteroid 170 km (110 mi) across 80 million years ago following an impact with a smaller body. The two largest presumed remnants of the parent asteroid aremain-belt asteroids298 Baptistina and1696 Nurmela. The Baptistina family is part of the largerFlora clan.[1][2] It was briefly speculated that theChicxulub impactor was part of the Baptistina family of asteroids, but this was disproven in 2011 using data from theWide-field Infrared Survey Explorer (WISE).
The Baptistina family consists of darkly colored asteroids andmeteoroids in similar orbits. Baptistina broke up into thousands of fragments about 80 million years ago.[3]
| Discovery | |
|---|---|
| Discovered by | Auguste Charlois |
| Discovery date | 9 September 1890 |
| Designations | |
| (298) Baptistina | |
| A890 RB | |
| |
| Orbital characteristics[4] | |
| Epoch 31 July 2019 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 123.99 yr (45289 d) |
| Aphelion | 2.4805 AU (371.08 Gm) |
| Perihelion | 2.0475 AU (306.30 Gm) |
| 2.2640 AU (338.69 Gm) | |
| Eccentricity | 0.095630 |
| 3.41 yr (1244.3 d) | |
| 209.69° | |
| 0° 17m 21.588s / day | |
| Inclination | 6.2884° |
| 8.2161° | |
| 135.004° | |
| Physical characteristics | |
| Dimensions | 13–30 km[5][6] |
| X-type | |
| 11.2 | |
298 Baptistina is the namesake asteroid and largest presumed remnant of the Baptistina family. It was discovered on 9 September 1890 byAuguste Charlois at theNice Observatory. The source of its name is unknown.[7] It measures about 13 to 30 kilometres (8 to 19 mi) in diameter. Although it has an orbit similar to theFlora family asteroids, Baptistina is an unrelated interloper.[8][verification needed]
Other members of the Baptistina family include1696 Nurmela,2858 Carlosporter, and(7255) 1993 VY1.[1]
It was originally thought that the Baptistina family may consist of uncommoncarbonaceous chondrite. In 2006, nine asteroids within the Baptistina family were given known classifications: three areS-type asteroids, two areX-type asteroids, another two areA/R-type asteroids, one isC-type and one isV-type. However, any conclusions taken from this were highly speculative, as very few members in the family were classified, and not even thealbedo of the meteors was known at the time.[1]
Following the impact of theChelyabinsk meteor in 2013, a paper published in the journalIcarus showed that shock produced during impact of a large asteroid can darken otherwise bright silicate material. Spectral analysis of the darkly-colored portions of the non-carbonaceousChelyabinsk meteorite closely matched the color of members of the Baptistina family, showing that a low albedo does not necessarily indicate the composition of the family.[9]
In 2007, it was proposed thatchromium concentrations in 66-million-year-old sediment layers at theCretaceous–Paleogene boundary (K–T boundary) on Earth suggested that theimpactor that gouged outChicxulub Crater and caused theCretaceous–Paleogene extinction event belonged to the Baptistina family.[10][11] Concerns were raised regarding the reputed link, in part because very few solid observational constraints existed of the asteroid or family.[6] One year later, it was discovered that 298 Baptistina does not share the same chemical signature as the source of theCretaceous–Paleogene boundary.[5] Because of the timeframe, it had also been suggested that the impactor that produced the lunar craterTycho 108 million years ago was also a member of the group,[12] as well as theVenusian cratersMead,Isabella,Meitner, and Klenova.[11]
In 2011, data from theWide-field Infrared Survey Explorer (WISE) 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 theK–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.[3] "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 theNear Earth Object Observation Program.[13]
