Hydrogen masers reveal new secrets of a massive star

Whereas utilizing the Atacama Giant Millimeter/submillimeter Array (ALMA) to review the masers round oddball star MWC 349A scientists found one thing sudden: a beforehand unseen jet of fabric launching from the star’s gasoline disk at impossibly excessive speeds. What’s extra, they imagine the jet is attributable to robust magnetic forces surrounding the star.

The invention might assist researchers to know the character and evolution of huge stars and the way hydrogen masers are shaped in space. The brand new observations have been introduced in the present day (January 9) in a press conference at the 241st meeting of the American Astronomical Society (AAS) in Seattle, Washington.

Positioned roughly 3,900 light-years away from Earth within the constellation Cygnus, MWC 349A’s distinctive options make it a sizzling spot for scientific research in optical, infrared, and radio wavelengths. The huge star—roughly 30 occasions the mass of the sun—is among the brightest radio sources within the sky, and one in all solely a handful of objects identified to have hydrogen masers. These masers amplify microwave radio emissions, making it simpler to review processes which are sometimes too small to see. It’s this distinctive function that allowed scientists to map MWC 349A’s disk intimately for the primary time.

“A maser is sort of a naturally occurring laser,” mentioned Sirina Prasad, an undergraduate analysis assistant on the Heart for Astrophysics | Harvard & Smithsonian (CfA), and the first writer of the paper. “It is an space in outer space that emits a very shiny type of mild. We are able to see this mild and hint it again to the place it got here from, bringing us one step nearer to determining what’s actually happening.”

Leveraging the resolving energy of ALMA’s Band 6, developed by the U.S. Nationwide Science Basis’s Nationwide Radio Astronomy Observatory (NRAO), the crew was in a position to make use of the masers to uncover the beforehand unseen buildings within the star’s quick surroundings. Qizhou Zhang, a senior astrophysicist at CfA, and the undertaking’s principal investigator added, “We used masers generated by hydrogen to probe the bodily and dynamic buildings within the gasoline surrounding MWC 349A and revealed a flattened gasoline disk with a diameter of fifty au, roughly the dimensions of the Photo voltaic System, confirming the near-horizontal disk construction of the star. We additionally discovered a fast-moving jet element hidden throughout the winds flowing away from the star.”

The noticed jet is ejecting materials away from the star at a blistering 500 km per second. That is akin to touring the space between San Diego, California, and Phoenix, Arizona, within the literal blink of a watch. In accordance with researchers, it’s possible {that a} jet transferring this quick is being launched by a magnetic drive. Within the case of MWC 349A, that drive might be a magnetohydrodynamic wind—a kind of wind whose motion is dictated by the interaction between the star’s magnetic area and gases current in its surrounding disk.

“Our earlier understanding of MWC 349A was that the star was surrounded by a rotating disk and photo-evaporating wind. Sturdy proof for an extra collimated jet had not but been seen on this system. Though we do not but know for sure the place it comes from or how it’s made, it might be {that a} magnetohydrodynamic wind is producing the jet, during which case the magnetic area is chargeable for launching rotating materials from the system,” mentioned Prasad. “This might assist us to raised perceive the disk-wind dynamics of MWC 349A, and the interaction between circumstellar disks, winds, and jets in different star techniques.”