Nav: Home

How newborn stars prepare for the birth of planets

February 20, 2020

An international team of astronomers used two of the most powerful radio telescopes in the world to create more than three hundred images of planet-forming disks around very young stars in the Orion Clouds. These images reveal new details about the birthplaces of planets and the earliest stages of star formation.

Most of the stars in the universe are accompanied by planets. These planets are born in rings of dust and gas, called protoplanetary disks. Even very young stars are surrounded by these disks. Astronomers want to know exactly when these disks start to form, and what they look like. But young stars are very faint, and there are dense clouds of dust and gas surrounding them in stellar nurseries. Only highly sensitive radio telescope arrays can spot the tiny disks around these infant stars amidst the densely packed material in these clouds.

For this new research, astronomers pointed both the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) to a region in space where many stars are born: the Orion Molecular Clouds. This survey, called VLA/ALMA Nascent Disk and Multiplicity (VANDAM), is the largest survey of young stars and their disks to date.

Very young stars, also called protostars, form in clouds of gas and dust in space. The first step in the formation of a star is when these dense clouds collapse due to gravity. As the cloud collapses, it begins to spin - forming a flattened disk around the protostar. Material from the disk continues to feed the star and make it grow. Eventually, the left-over material in the disk is expected to form planets.

Many aspects about these first stages of star formation, and how the disk forms, are still unclear. But this new survey provides some missing clues as the VLA and ALMA peered through the dense clouds and observed hundreds of protostars and their disks in various stages of their formation.

Young planet-forming disks

"This survey revealed the average mass and size of these very young protoplanetary disks," said John Tobin of the National Radio Astronomy Observatory (NRAO) in Charlottesville, Virginia, and leader of the survey team. "We can now compare them to older disks that have been studied intensively with ALMA as well."

What Tobin and his team found, is that very young disks can be similar in size, but are on average much more massive than older disks. "When a star grows, it eats away more and more material from the disk. This means that younger disks have a lot more raw material from which planets could form. Possibly bigger planets already start to form around very young stars."

Four special protostars

Among hundreds of survey images, four protostars looked different than the rest and caught the scientists' attention. "These newborn stars looked very irregular and blobby," said team member Nicole Karnath of the University of Toledo, Ohio (now at SOFIA Science Center). "We think that they are in one of the earliest stages of star formation and some may not even have formed into protostars yet."

It is special that the scientists found four of these objects. "We rarely find more than one such irregular object in one observation," added Karnath, who used these four infant stars to propose a schematic pathway for the earliest stages of star formation. "We are not entirely sure how old they are, but they are probably younger than ten thousand years."

To be defined as a typical (class 0) protostar, stars should not only have a flattened rotating disk surrounding them, but also an outflow - spewing away material in opposite directions - that clears the dense cloud surrounding the stars and makes them optically visible. This outflow is important, because it prevents stars from spinning out of control while they grow. But when exactly these outflows start to happen, is an open question in astronomy.

One of the infant stars in this study, called HOPS 404, has an outflow of only two kilometers (1.2 miles) per second (a typical protostar-outflow of 10-100 km/s or 6-62 miles/s). "It is a big puffy sun that is still gathering a lot of mass, but just started its outflow to lose angular momentum to be able to keep growing," explained Karnath. "This is one of the smallest outflows that we have seen and it supports our theory of what the first step in forming a protostar looks like."

Combining ALMA and VLA

The exquisite resolution and sensitivity provided by both ALMA and the VLA were crucial to understand both the outer and inner regions of protostars and their disks in this survey. While ALMA can examine the dense dusty material around protostars in great detail, the images from the VLA made at longer wavelengths were essential to understand the inner structures of the youngest protostars at scales smaller than our solar system.

"The combined use of ALMA and the VLA has given us the best of both worlds," said Tobin. "Thanks to these telescopes, we start to understand how planet formation begins."
-end-
The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Media contact:

Iris Nijman
News and Public Information Manager
National Radio Astronomy Observatory (NRAO)
inijman@nrao.edu
+1 (434) 296-0314

This research was presented in two papers:

The VLA/ALMA Nascent Disk and Multiplicity (VANDAM) Survey of Orion Protostars. A Statistical Characterization of Class 0 and I Protostellar Disks," by J. Tobin et al., The Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab6f64

"Detection of Irregular, Sub-mm Opaque Structures in the Orion Molecular Clouds: Protostars within 10000 years of formation?," by N. Karnath et al., The Astrophysical Journal. https://doi.org/10.3847/1538-4357/ab659e

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

National Radio Astronomy Observatory

Related Star Formation Articles:

Astronomers turn up the heavy metal to shed light on star formation
Astronomers from The University of Western Australia's node of the International Centre for Radio Astronomy Research (ICRAR) have developed a new way to study star formation in galaxies from the dawn of time to today.
New observations of black hole devouring a star reveal rapid disk formation
When a star passes too close to a supermassive black hole, tidal forces tear it apart, producing a bright flare of radiation as material from the star falls into the black hole.
How galaxies die: New insights into the quenching of star formation
Astronomers studying galaxy evolution have long struggled to understand what causes star formation to shut down in massive galaxies.
The cosmic commute towards star and planet formation
Interconnected gas flows reveal how star-forming gas is assembled in galaxies.
Star formation project maps nearby interstellar clouds
Astronomers have captured new, detailed maps of three nearby interstellar gas clouds containing regions of ongoing high-mass star formation.
Scientists discover pulsating remains of a star in an eclipsing double star system
Scientists from the University of Sheffield have discovered a pulsating ancient star in a double star system, which will allow them to access important information on the history of how stars like our Sun evolve and eventually die.
Distant milky way-like galaxies reveal star formation history of the universe
Thousands of galaxies are visible in this radio image of an area in the Southern Sky, made with the MeerKAT telescope.
Cascades of gas around young star indicate early stages of planet formation
What does a gestating baby planet look like? New research in Nature by a team including Carnegie's Jaehan Bae investigated the effects of three planets in the process of forming around a young star, revealing the source of their atmospheres.
Massive exoplanet orbiting tiny star challenges planet formation theory
Astronomers have discovered a giant Jupiter-like exoplanet in an unlikely location -- orbiting a small red dwarf star.
ALMA pinpoints the formation site of planet around nearest young star
Researchers using ALMA (Atacama Large Millimeter/submillimeter Array) found a small dust concentration in the disk around TW Hydrae, the nearest young star.
More Star Formation News and Star Formation Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Warped Reality
False information on the internet makes it harder and harder to know what's true, and the consequences have been devastating. This hour, TED speakers explore ideas around technology and deception. Guests include law professor Danielle Citron, journalist Andrew Marantz, and computer scientist Joy Buolamwini.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.