For decades astronomers debated the source of the most common type of meteorites that fall on Earth called H ordinary chondrites. A new study by researchers at the Planetary Science Institute sheds some light on the origin of these meteorites in the main asteroid belt between Mars and Jupiter.
“H-chondrites make up 33 percent of all the meteorites that fall on Earth, yet their origin has been the source of debate for the last few decades. We have now added an important piece to this puzzle that will contribute to resolve this debate,” said Juan Sanchez, an associate research scientist at PSI who is the lead author of a paper published in The Astrophysical Journal.
H ordinary chondrites have been traditionally linked to (6) Hebe, a large asteroid located in the inner part of the main asteroid belt. This study, however, shows that some of these meteorites might have originated in a more distant region of the main belt.
The team of astronomers, which included PSI researchers Vishnu Reddy and Lucille Le Corre, studied minerals on the surface of a near-Earth asteroid named (214869) 2007 PA8 using the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawai’i during its close approach to Earth during November 2012. These observations showed that H ordinary chondrite meteorites came from an asteroid similar to 2007 PA8.
2007 PA8, like all near-Earth asteroids, comes from the main asteroid belt. However, its orbit places the origin of this object in the outer regions of the main belt.
“The fact that a near-Earth asteroid with this orbit has a composition similar to H-chondrites suggests that some of these meteorites might not be related to (6) Hebe, nor originated in the inner part of the main belt,” Sanchez said.
“Moreover, it allows us to link H-chondrites to some specific asteroid families in the outer part of the main belt. Our study shows that the Koronis family is the most likely source region for 2007 PA8, and possibly the source for some of the H-chondrites that fall on Earth,” he said.
Above, this diagram shows the orbits of potential sources of H ordinary chondrites, the most common type of meteorite that falls on Earth.