By Andy Tomaswick
March 16, 2025
Despite their general similarities, asteroids usually differ quite a bit. For example, Vesta has a completely different spectroscopic profile than psyche. No wonder that another of the main -sancids – pallas – is in its own class, except for around 300 members of his “family” with similar orbital profiles and spectroscopic lines. A new paper from researchers who then visited astronomers in the infrared telescopic facility of the NASA (IRTF) in Haiwi'i took a look at members of this family in the infrared and compared them with a certain near-earth object that may have a similar make-up.
Pallas has been examined for decades, in view of his position as the third largest asteroid in the asteroid belt behind Ceres and Vesta. However, his 513 km diameter is not the most unique thing about him – it is the fact that it is blue.
In this case “blue” is relative. Like stars, a “blue” asteroid would not necessarily appear blue for the mere eye – it only has spikes on certain spectroscopic frequencies connected to this light color. The spectroscopic profile of Pallas is firmly in the B-Type category, a special version of a low-carbon asteroid from the C-type with blue color and it only makes up about 4% of the total number of asteroids known to science.
Fraser describes what makes the asteroid belt the asteroid belt.
While Pallas has been a well -known example of this rare asteroid for some time, there are many that have not been examined as much. Pallas has a “family” that shares a similar spectographic profile to his parent, but they have never been examined in detail.
Asteroid families are generated when the overarching body is hit by another large object in this case, and fragments of this overarching body are expelled into space, but only quickly enough to fall into the orbits that are slightly removed from the parent. Usually you have attributes such as orbital eccentricity, speed and especially for this study of spectroscopic profile. In a study in 1994 it was first found that Pallas had a family that mainly consisted of asteroids with a diameter of less than 20 km. What you lack in the total size, make it good again – there are estimated 300 asteroids in the family of Pallas.
The authors of the study examined 23 members of the Pallas family who use the NIR camera (near infrared) at the IRTF, and found spectrographic profiles that were mainly similar. However, these profiles do not quite fit in standard categorizations of meteors, which are often used to examine the compositions of asteroids without actually visiting them. According to the study, the CY and CI meteorites, which are known to be subjected to a certain time of their lives, both in the water based on water and heat-based transformations. However, some family members imitate close CM and CK chondritemeors, which are mainly affected by only water.
Video that describes pallas, the third largest asteroid in the asteroid belt.
Credit – Factoid Media YouTube Canal
The study gives the idea that Pallas and its large family of asteroids consist of hydrated materials – in other words, they contain water. That would explain the “blue” spectra, even if they are not visible to the mere eye. But the authors did not stop here – they wanted to see whether there was accidentally a Rogue family member who was much closer to their home.
Pallas and his family have a very high tendency towards around 35 °, which makes it difficult for spaceships to reach them so far from the plan of the ecliptic. An almost earth's asteroid, which is known as (3200) Phaethon, has long been considered a member of the Pallas family, which was thrown at the earth and then much closer to the earth.
Phaeton, the orbit of which brought it to around 10 million km of earth in 2017, shares a large part of the spectral profile as a Pallas family. It is particularly blue and, according to the study, divides similar spectral profiles to around 10% of the asteroids of the Pallas family in its size category. This makes a strong argument for involving Phaeton as a member of the rogue member of the family, which was thrown out of their environment either by gravity or an impact. Above all, however, this means that we may be able to investigate the composition of this asteroid family by sending a mission to you.
Such a mission is already in the works, but it will take a while for it to start. Until then, there are still many asteroids in the Pallas family who can study as many spectral wavelengths as possible. When we start moving into the solar system, this work becomes even more critical.
Learn more:
P. Chavan et al. – Spectroscopic characterization of the Pallas family almost infrarotic
Ut – new pictures of the “golf ball” asteroid pallas
Ut – now it's time to see asteroid pallas from its best side
Ut – what is the asteroid belt?
