Scientists studied over 300 images of planet-forming disks generated by the two strongest radio telescopes in the world to research when protoplanetary begin their development.
The Orion Molecular Clouds was the target of the VANDAM survey. The yellow dots show the location of observed protostars. - Image Credit: ALMA (ESO/NAOJ/NRAO), J. Tobin; NRAO/AUI/NSF, S. Dagnello; Herschel/ESA - Edited by Universal-Sci - CC BY 3.0
Scientists studied over 300 images of planet-forming disks generated by the two strongest radio telescopes in the world, the Atacama Large Millimeter Array (ALMA) and the Very Large Array (VLA). The images revealed new information about the formation of planets in infant solar systems.
Experts suspect that the vast majority of stars in the cosmos have exoplanets orbiting around them. In any case, we know that in the Milky Way, there is, at minimum, one planet on average per star. In addition, approximately 20% of planetary systems with a star similar to our sun contain earth-sized planets. Planets are born in so-called protoplanetary disks, a turning circumstellar disk of compressed gas and dust encircling a young recently developed star.
An international team of researchers and astronomers wanted to find out precisely what these these protoplanetary disks look like as well as when they begin to develop. The problem is that infant stars are tough to spot because they are very faint and surrounded by dense clouds of gas. Excellent reasons for using the highly sensitive ALMA van VLA telescopes.
An ideal collaboration between the ALMA and VLA telescopes
The excellent sensitivity and resolution on offer by these beforementioned telescopes proved crucial in comprehending the inner and outer regions of young protoplanetary disks and their protostars. ALMA is well equipped for the analysis of the dense, dusty materials around protostars in high resolution. At the same time, the VLA is better at detecting longer wavelengths, which is ideal for understanding the inner composition of the youngest protostar at scales smaller than our own solar system.
The research team studied over three hundred protostars and their disks. Shown here is a subgroup of stars,. The ALMA and VLA data compliment each other: ALMA sees the outer disk structure in blue, and the VLA shows the inner disks and star cores in orange.
Image Credit: ALMA (ESO/NAOJ/NRAO), J. Tobin; NRAO/AUI/NSF, S. Dagnello
John Tobin from the NRAO and head of the survey team stated in an interview that as the survey unveiled the average size and mass of these very early protoplanetary disks, scientists can now compare them with older disks that have been studied in the past. He continued to explain they discovered that early disks are similar in size while their mass is much higher than the mass of older disks. This is explained by the fact that developing stars eat away more material from the protoplanetary disk as time goes on, meaning that younger disks have a lot more raw material from which planets could form. It is possible that larger planets already start their formation proces around very early stars.
4 unique discoveries
The researchers discovered four rather unique protostars among the more than 300 survey images. According to Nicole Karnath, a University of Toledo researcher, they had very different appearances compared to the other infant stars. The research team believes that their irregular shape is because they are in one of the earliest stages of star formation; some might not even have developed into protostars yet.
Astronomers rarely find more than a single irregular object like this in one observation. For the research team to find four of them in one go is pretty unique. A schematic pathway is now proposed for the earliest stages of star formation based on these four infant stars. The scientists are not sure of the exact age, but they estimate that they are presumably younger than 10.000 years.
Sources and further reading: NRAO press release - One or more bound planets per Milky Way star from microlensing observations - Prevalence of Earth-size planets orbiting Sun-like stars
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