Planets form from the debris and gas that surrounds untested whiz , but the particular of this process rest foggy . Better observations are challenging long - held assumptions , and now the Atacama Large Millimeter / submillimeter Array ( ALMA ) in Chile has measured the size of dust grains with unbelievable preciseness .
An international squad of researchers used ALMA to study HD 142527 , a 5 - million - year - old star twice the mass of the Sun . It is located 500 wakeful - years away , and its proximity has made it a perfect target for previous planetary formation studies .
In the study , published in theAstrophysical Journal Letters , the squad looked at how Inner Light is scattered in unlike directions by the dust grains , an gist get laid as polarization . The researchers were able to estimate that the size of rubble grains is at most 150 micron , about 10 times small-scale than previously intend .
“ In the previous studies , astronomers have count on the sizing ground on radio emissions assume hypothetical spherical dust subatomic particle , ” said Akimasa Kataoka , from Heidelberg University and the National Astronomical Observatory of Japan , in astatement . “ In our work , we observe the scattered radio wave through polarization , which carries independent selective information from the thermal dust expelling . Such a large difference in the approximate size of it of detritus particles implies that the old assumption might be wrong . ”
The previous mannikin and the current measurements are free-base on the assumption that dust grain are orbicular . To adjudicate the difference between observation and theory , the researchers proposed that dust grains have complicated structures , rather than just being little dusty balls . The complex feature would explain how brightness is scattered by the protoplanetary disk .
“ The polarization fraction of radio wafture from the dust platter around HD 142527 is only a few percent . Thanks to ALMA ’s high sensitiveness , we have detect such a tiny signal to derive information about the sizing and shape of the dust particle , ” add together Kataoka . “ This is the very first footstep in the research on dust evolution with polarimetry , and I believe the future progress will be full of excitement . ”
If dust grains are not petite spheres , astronomer might have to look at antecedently taken observation and reinterpret it in light of this finding . Who bonk , there might be some interesting new discovery hidden in the datum .
HD 142527 as see by ALMA . ALMA ( ESO / NAOJ / NRAO ) , Kataoka et al .
