"Long before it's in the papers"
March 19, 2016


Photo said to show possible embryonic planet

March 19, 2016
Courtesy of the National Radio Astronomy Observatory
and World Science staff

New pho­tographs ap­pear to show a clump of ma­te­ri­al cir­cling a young star—pos­sibly rep­re­sent­ing a plan­et in the ear­li­est stages of forma­t­ion ev­er seen, as­tro­no­mers claim.

Sci­en­tists used the Karl G. Jan­sky Very Large Ar­ray, a ra­di­o as­tron­o­my ob­serv­a­to­ry, to peer in­to the in­ner por­tion of a dusty disk sur­round­ing a star called HL Tau, a stel­lar re­gion where plan­ets typ­ic­ally form.

A­bove: Com­bined AL­MA/VLA im­age of HL Tau. Be­low: AL­MA im­age of HL Tau at left; VLA im­age, show­ing clump of dust, at right.. (Cred­it: Carrasco-Gonzalez, et al.; Bill Sax­ton, NRAO/AUI/NSF.)

As­tro­no­mers had stud­ied the struc­ture in 2014 with an­oth­er ob­serv­a­to­ry, the At­a­cama Large Mil­lime­ter/­sub­mil­lime­ter Ar­ray. That pro­duced what as­tro­no­mers then called the best im­age ev­er of plan­et forma­t­ion in prog­ress. 

The new im­ages are said to show bet­ter de­tail in the in­ner part of the disc be­cause the Very Large Ar­ray re­ceives long­er ra­di­o waves, which are more suit­a­ble to see this re­gion. The im­ages re­vealed a dis­tinct clump of dust there, con­tain­ing about enough ma­te­ri­al to make three to eight Earths, as­tro­no­mers said.

“We be­lieve this clump of dust rep­re­sents the ear­li­est stage in the forma­t­ion of protoplan­ets” or em­bry­on­ic plan­ets, said Thom­as Hen­ning of the Max Planck In­sti­tute for As­tron­o­my in Hei­del­berg, Ger­ma­ny, one of the re­search­ers.

“This is the first time we’ve seen that stage,” he added.

“We have not yet been able to ob­serve most stages in the pro­cess of plan­et forma­t­ion,” ex­plained Car­los Carrasco-Gonzalez Na­t­ional Au­ton­o­mous Uni­vers­ity of Mex­i­co, an­oth­er col­la­bo­ra­tor. 

“This is quite dif­fer­ent from the case of star forma­t­ion, where, in dif­fer­ent ob­jects, we have seen stars in dif­fer­ent stages of their life cy­cle. With plan­ets, we haven’t been so for­tu­nate, so get­ting a look at this very early stage in plan­et forma­t­ion is ex­tremely valua­ble.”

As­tro­no­mers be­lieve that clumps like the one iden­ti­fied in the im­age could slowly evolve in­to plan­ets by at­tract­ing ma­te­ri­al in­wards, through gra­vity, un­til the clump be­comes a dis­tinct ball of ma­te­ri­al.

HL Tau is an es­ti­mat­ed mil­lion years old—y­oung for a star—and lies about 450 light-years from Earth. A light-year is the dis­tance light trav­els in a year.

The sci­en­tists are re­port­ing their find­ings in the As­t­ro­phys­i­cal Jour­nal Let­ters.

* * *

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New photographs appear to show a clump of material circling a young star—possibly representing a planet in the earliest stages of formation ever seen, astronomers claim. Scientists used the Karl G. Jansky Very Large Array, a radio astronomy observatory, to peer into the inner portion of a dusty disk surrounding a star called HL Tau, a stellar region where planets typically form. Astronomers had studied the structure in 2014 with another observatory, the Atacama Large Millimeter/submillimeter Array, which produced what astronomers then called the best image ever of planet formation in progress. The new images are said to show better detail in the inner part of the disc because the Very Large Array receives longer radio waves, which are more suitable to see this region. The images revealed a distinct clump of dust there, containing about enough material to make three to eight Earths, astronomers said. “We believe this clump of dust represents the earliest stage in the formation of protoplanets” or embryonic planets, said Thomas Henning, of the Max Planck Institute for Astronomy in Heidelberg, Germany, one of the researchers. “This is the first time we’ve seen that stage,” he added. “We have not yet been able to observe most stages in the process of planet formation,” explained Carlos Carrasco-Gonzalez National Autonomous University of Mexico, another collaborator. “This is quite different from the case of star formation, where, in different objects, we have seen stars in different stages of their life cycle. With planets, we haven’t been so fortunate, so getting a look at this very early stage in planet formation is extremely valuable.” Astronomers believe that clumps like the one identified in the image could slowly evolve into planets by attracting material inwards, through gravity, until the clump becomes a distinct ball of material. HL Tau is an estimated million years old—young for a star—and lies about 450 light-years from Earth. A light-year is the distance light travels in a year. The scientists are reporting their findings in the Astrophysical Journal Letters.