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Newborn stars make a splash with astronomers

March 19, 2013
Courtesy of the Jet Propulsion Laboratory
and World Science staff

As­tro­no­mers have found some of the youngest stars ev­er seen, thanks to the Her­schel space ob­serv­a­to­ry, a Eu­ro­pe­an Space Agen­cy mis­sion with NASA con­tri­bu­tions.

The find­ings br­ing sci­en­tists “closer to wit­ness­ing the mo­ment when a star be­gins to form,” said Amel­ia Stutz, lead au­thor of a pa­per to ap­pear in The As­t­ro­phys­i­cal Jour­nal and a post­doc­tor­al re­search­er at the Max Planck In­sti­tute for As­tronomy in Hei­del­berg, Ger­ma­ny. 

The ob­jects are the larg­est known “ensem­ble of such young stars in a sin­gle star-forming re­gion,” she added.

Thick clouds of gas and dust are said to sur­round the 15 fledg­ing stars, mak­ing their de­tec­tion dif­fi­cult. They turned up by sur­prise in a sur­vey of the big­gest site of star forma­t­ion near our so­lar sys­tem—in the con­stella­t­ion Ori­on—giv­ing sci­en­tists a peek in­to one of the ear­li­est, least un­der­stood phases of star forma­t­ion.

Ob­serva­t­ions from NASA’s Spitzer Space Tel­e­scope and the At­a­cama Path­find­er Ex­pe­ri­ment tel­e­scope in Chil­e con­tri­but­ed to the find­ings.

Stars spring to life as huge clouds of gas and dust shrink in on them­selves due to gra­vity. They change from stray, cool gas to a ball of super-hot ma­te­ri­al called plas­ma—a star. This shift is quick by cos­mic stan­dards, last­ing only a few hun­dred thou­sand years, and find­ing stars in this fledg­ling stage is hard.

Side-by-side images of the same region, using different telescopes, around the nebula Messier 78 where several of 15 new protostars were found. Herschel detected the extremely young protostars -- indicated in the image by the four circles -- that were too cold to be picked up in previous scans of the area by NASA's Spitzer Space Telescope. (Image credit: NASA/ESA/ESO/JPL-Caltech/Max-Planck Institute for Astronomy)

As­tro­no­mers long had in­ves­t­i­gated the stel­lar nurse­ry in the Ori­on Mo­lec­u­lar Cloud Com­plex, a vast col­lec­tion of star-forming clouds, but had not seen the new­born stars, or pro­to­stars, un­til Her­schel ob­served the re­gion.

“Pre­vi­ous stud­ies have missed the dens­est, youngest and po­ten­tially most ex­treme and cold pro­to­stars in Ori­on,” Stutz said. “These sources may be able to help us bet­ter un­der­stand how the pro­cess of star forma­t­ion pro­ceeds at the very ear­li­est stages, when most of the stel­lar mass is built up and phys­i­cal con­di­tions are hard­est to ob­serve.”

Her­schel spied the objects in far-infrared light, a type of light not en­er­get­ic enough to be de­tected by our eyes. But far-infrared can shine through the thick clouds around bur­geon­ing stars that block out higher-energy col­ors that we can see.

“Our ob­serva­t­ions pro­vide a first glimpse at pro­to­stars that have just be­gun to ‘glow,’” said study coau­thor Elise Furlan, a post­doc­tor­al re­search as­so­ci­ate at the Na­t­ional Op­ti­cal As­tronomy Ob­servatory in Tuc­son, Ariz.

Of the 15 newly dis­cov­ered pro­to­stars, 11 pos­sess very “red” col­ors, mean­ing their light out­put trends to­ward the low-energy end of the spec­trum, as­tro­no­mers said. This out­put in­di­cates the stars are still em­bed­ded deeply in a gas­e­ous en­ve­lope, mean­ing they are very young. An ad­di­tion­al sev­en pro­to­stars pre­vi­ously seen by Spitzer share this char­ac­ter­is­tic, the sci­en­tists said. To­geth­er, these 18 bud­ding stars com­prise only five per­cent of the pro­to­stars and can­di­date pro­to­stars ob­served in Ori­on, they added. That fig­ure im­plies the very youngest stars spend per­haps 25,000 years in this phase of their de­vel­op­ment, a mere blink of an eye con­sid­er­ing a star like our sun lives for about 10 bil­lion years.

Re­search­ers hope to doc­u­ment chron­o­log­ic­ally each stage of a star’s de­vel­op­ment rath­er like a family al­bum, from be­fore birth to early in­fan­cy, when plan­ets al­so take shape. With the find­ings, “we add an im­por­tant mis­sing pho­to to the family al­bum,” said Glenn Wahl­gren, Her­schel Pro­gram Sci­ent­ist at NASA Head­quar­ters in Wash­ing­ton.


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Astronomers have found some of the youngest stars ever seen, thanks to the Herschel space observatory, a European Space Agency mission with NASA contributions. The findings bring scientists “closer to witnessing the moment when a star begins to form,” said Amelia Stutz, lead author of a paper to be published in The Astrophysical Journal and a postdoctoral researcher at the Max Planck Institute for Astronomy in Heidelberg, Germany. The objects are the largest known “ensemble of such young stars in a single star-forming region,” she added. Thick clouds of gas and dust are said to surround the 15 fledging stars, making their detection difficult. They turned up by surprise in a survey of the biggest site of star formation near our solar system—in the constellation Orion—giving scientists a peek into one of the earliest, least understood phases of star formation. Observations from NASA’s Spitzer Space Telescope and the Atacama Pathfinder Experiment telescope in Chile contributed to the findings. Stars spring to life as huge clouds of gas and dust shrink in on themselves due to gravity. They change from stray, cool gas to a ball of super-hot material called plasma—a star. This shift is quick by cosmic standards, lasting only a few hundred thousand years, and finding stars in this fledgling stage is hard. Astronomers long had investigated the stellar nursery in the Orion Molecular Cloud Complex, a vast collection of star-forming clouds, but had not seen the newborn stars, or protostars, until Herschel observed the region. “Previous studies have missed the densest, youngest and potentially most extreme and cold protostars in Orion,” Stutz said. “These sources may be able to help us better understand how the process of star formation proceeds at the very earliest stages, when most of the stellar mass is built up and physical conditions are hardest to observe.” Herschel spied the protostars in far-infrared light, a type of light not energetic enough to be detected by our eyes. But far-infrared can shine through the thick clouds around burgeoning stars that block out higher-energy colors that we can see. “Our observations provide a first glimpse at protostars that have just begun to ‘glow’” said study coauthor Elise Furlan, a postdoctoral research associate at the National Optical Astronomy Observatory in Tucson, Ariz. Of the 15 newly discovered protostars, 11 possess very “red” colors, meaning their light output trends toward the low-energy end of the spectrum, astronomers said. This output indicates the stars are still embedded deeply in a gaseous envelope, meaning they are very young. An additional seven protostars previously seen by Spitzer share this characteristic, the scientists said. Together, these 18 budding stars comprise only five percent of the protostars and candidate protostars observed in Orion, they added. That figure implies the very youngest stars spend perhaps 25,000 years in this phase of their development, a mere blink of an eye considering a star like our sun lives for about 10 billion years. Researchers hope to document chronologically each stage of a star’s development rather like a family album, from before birth to early infancy, when planets also take shape. “With these recent findings, we add an important missing photo to the family album of stellar development,” said Glenn Wahlgren, Herschel Program Scientist at NASA Headquarters in Washington. “Herschel has allowed us to study stars in their infancy.”