Artists impression of the red hypergiant star VY Canis Majoris. Located about 3,009 light-years from Earth, VY Canis Majoris is potentially the most enormous star in the Milky Way. Severe supergiant stars understood as hypergiants are really uncommon, with only a few known to exist in the Milky Way. Unlike stars with lower masses– which are more likely to puff up when they enter the red giant phase however usually keep a spherical shape– hypergiants tend to experience significant, erratic mass loss occasions that form complex, extremely irregular structures composed of knots, arcs, and clumps.
From these data, the group built an image of the worldwide molecular outflow structure of VY CMa on scales that incorporated all ejected material from the star.
Artists impression of the red hypergiant star VY Canis Majoris. Located about 3,009 light-years from Earth, VY Canis Majoris is possibly the most enormous star in the Milky Way. Credit: NASA/ ESA/ Hubble/ R. Humphreys, University of Minnesota/ J. Olmsted, STScI/ hubblesite.org
By tracing molecular emissions in the outflows around the red hypergiant star VY Canis Majoris, astronomers have actually acquired the very first comprehensive map of the stars envelope, which clarifies the mechanisms included in the lasts of severe supergiant star.
A University of Arizona-led team of astronomers has created a detailed, three-dimensional image of a passing away hypergiant star. The group, led by UArizona researchers Ambesh Singh and Lucy Ziurys, traced the circulation, instructions, and speeds of a range of molecules surrounding a red hypergiant star known as VY Canis Majoris.
Their findings, which they provided on June 13, 2022, at the 240th Meeting of the American Astronomical Society in Pasadena, California, provide insights, at an unmatched scale, into the processes that accompany the death of giant stars. The work was finished with collaborators Robert Humphreys from the University of Minnesota and Anita Richards from the University of Manchester in the United Kingdom.
Severe supergiant stars referred to as hypergiants are very unusual, with just a couple of known to exist in the Milky Way. Examples include Betelgeuse, the 2nd brightest star in the constellation Orion, and NML Cygni, also understood as V1489 Cygni, in the constellation Cygnus. Unlike stars with lower masses– which are most likely to puff up as soon as they go into the red huge phase however typically retain a spherical shape– hypergiants tend to experience considerable, erratic mass loss events that form complex, extremely irregular structures made up of knots, arcs, and clumps.
Located about 3,009 light-years from Earth, VY Canis Majoris– or VY CMa, for brief– is a pulsating variable star in the a little southern constellation of Canis Major. Spanning anywhere from 10,000 to 15,000 huge systems (with 1 AU being the typical distance in between Earth and the sun) VY CMa is perhaps the most massive star in the Milky Way, according to Ziurys.
” Think of it as Betelgeuse on steroids,” said Ziurys, a Regents Professor with joint appointments in UArizona Department of Chemistry and Biochemistry and Steward Observatory, both part of the College of Science. “It is much larger, much more enormous and goes through violent mass eruptions every 200 years or so.”
Because it is one of the best examples of these types of stars, the group chose to study VY CMa.
” We are especially thinking about what hypergiant stars do at end of their lives,” stated Singh, a fourth-year doctoral student in Ziurys laboratory. “People used to believe these enormous stars just progress into supernovae surges, but we are no longer sure about that.”
” If that were the case, we must see lots of more supernovae explosions throughout the sky,” Ziurys added. “We now think they might silently collapse into black holes, however we dont know which ones end their lives like that, or why that happens and how.”
Previous imaging of VY CMa with NASAs Hubble Space Telescope and spectroscopy showed the presence of other clumps and unique arcs and knots, lots of extending countless AU from the central star. To discover more details of the processes by which hypergiant stars end their lives, the team set out to trace particular particles around the hypergiant and map them to preexisting images of the dust, taken by the Hubble Space Telescope.
” Nobody has had the ability to make a total image of this star,” Ziurys stated, describing that her team set out to understand the systems by which the star sheds mass, which appear to be various from those of smaller sized stars entering their red huge phase at the end of their lives.
” You dont see this good, in proportion mass loss, however rather convection cells that blow through the stars photosphere like giant bullets and eject mass in various instructions,” Ziurys said. “These are comparable to the coronal arcs seen in the sun, but a billion times bigger.”
The team utilized the Atacama Large Millimeter Array, or ALMA, in Chile to trace a range of molecules in material ejected from the outstanding surface area. While some observations are still in progress, initial maps of sulfur oxide, sulfur dioxide, silicon oxide, phosphorous oxide and salt chloride were gotten. From these information, the group built an image of the global molecular outflow structure of VY CMa on scales that included all ejected product from the star.
” The particles trace the arcs in the envelope, which informs us particles and dust are well-mixed,” Singh said. “The great feature of emissions of molecules at radio wavelengths is that they supply us with speed details, as opposed to the dust emission, which is static.”
By moving ALMAs 48 radio dishes into different configurations, the scientists were able to acquire details about the directions and speeds of the molecules and map them across the various regions of the hypergiants envelope in significant detail, even associating them to various mass ejection occasions over time.
Processing the data needed some heavy lifting in regards to computing power, Singh stated.
” So far, we have processed almost a terabyte from ALMA, and we still get information that we need to go through to get the very best resolution possible,” he stated. “Just calibrating and cleaning up the information needs approximately 20,000 versions, which takes a day or 2 for each particle.”
” With these observations, we can now put these on maps on the sky,” Ziurys stated. “Until now, only little portions of this enormous structure had actually been studied, but you cant understand the mass loss and how these big stars pass away unless you look at the whole region. Thats why we wanted to develop a total image.”
With funding from the National Science Foundation, the team prepares to publish its findings in a series of documents.
Satisfying: 240th conference of the American Astronomical Society
