Astronomers Discover Jets from Massive Protostars Might be Very Different from Lower-Mass Systems

Young Star Cep A HW2

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Artist’s conception of the young star Cep A HW2, revealing a wide-angle wind coming from near to the star and a disk of product orbiting the star (called an accretion disk), with a much narrower jet further away. Credit: Bill Saxton, NRAO/AUI/NSF

VLA exposes brand-new information of protostellar jet.

Astronomers studying the fast-moving jet of product ejected by a still-forming, enormous young star discovered a significant distinction in between that jet and those ejected by less-massive young stars. The researchers made the discovery by utilizing the U.S. National Science Foundation’s Karl G. Jansky Very Large Array (VLA) to make the most in-depth image yet of the inner area of such a jet originating from an enormous young star.

VLA Protostar Cep A HW2

VLA picture of the jet from protostar Cep A HW2. Credit: Carrasco-Gonzalez et al., Bill Saxton, NRAO/AUI/NSF

Both low- and high-mass young stars, or protostars, move jets external perpendicular to a disk of product carefully orbiting the star. In stars with masses comparable to the Sun, these jets are narrowed, or focused, reasonably securely close to the star in a procedure called collimation. Because most high-mass protostars are more far-off, studying the areas near to them has actually been harder, so astronomers were uncertain if this held true with them.

A group of researchers observed an enormous protostar called Cep A HW2, situated about 2,300 light-years from Earth in the constellation Cepheus. Cep A HW2 is anticipated to turn into a brand-new star about 10 times more enormous than the Sun. The brand-new VLA images revealed the finest information yet seen in such a things, providing the astronomers their very first view of the inner part of the jet, a part approximately as long as the size of the Solar System.

VLA Jet From Protostar Cep A HW2

VLA picture of the jet from protostar Cep A HW2, with surrounding location displayed in Hubble Space Telescope image. Circles show place of the accretion disk, not seen in this image. Credit: Carrasco-Gonzalez et al.; Bill Saxton, NRAO/AUI/NSF; STScI

“What we saw is very different from what usually is seen in the jets from low-mass stars,” stated Adriana Rodriguez-Kamenetzky, of the National Autonomous University of Mexico (UNAM).

In lower-mass protostars, observations have actually revealed the jets to be parallelled as near to the star as just a few times the Earth-Sun range.

In Cep A HW2, nevertheless, “We see not a single jet, but two things — a wide-angle wind originating close to the star, then a highly-collimated jet some distance away,” stated Alberto Sanna, of the Osservatorio Astronomico di Cagliari (INAF) in Italy. The parallelled jet starts at a range from the star equivalent to the range from the Sun to Uranus or Neptune.

Young Star Cep A HW2 Labeled

Artist’s conception of Cep A HW2 and its jet, with labels. Credit: Bill Saxton, NRAO/AUI/NSF

The discovery raises 2 primary possibilities, the astronomers stated.

Cep A HW2 Sky Chart

Location of Cep A HW2 in the sky. Credit: Bill Saxton, NRAO/AUI/NSF

First, the very same system might be at work in both high-mass and low-mass protostars, however the collimation range might be figured out by the mass, happening further away in more-massive systems. The 2nd possibility is that high-mass stars may produce just the wide-angle wind seen in Cep A HW2, with collimation just coming when physical conditions around the star limit the circulation.

“That case would point to a major difference in the mechanisms at work in protostars of different masses,” stated Carlos Carrasco-Gonzalez, likewise of UNAM, leader of the work. “Answering this question is important to understanding how stars of all masses form,” he included.

Carrasco-Gonzalez and his coworkers are reporting their findings in the Astrophysical Journal.

Reference: “Zooming into the Collimation Zone in a Massive Protostellar Jet” by Carlos Carrasco-González, Alberto Sanna, Adriana Rodríguez-Kamenetzky, Luca Moscadelli, Melvin Hoare, José M. Torrelles, Roberto Galván-Madrid and Andrés F. Izquierdo, Accepted, Astrophysical Journal.
arXiv: 2106.01235

The National Radio Astronomy Observatory is a center of the National Science Foundation, run under cooperative contract by Associated Universities, Inc.

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