Coronal rain on the Sun with Earth superimposed for scale. New high-resolution spectrographic observations of a flare on a faint far-off star using the Penn State Habitable-zone Planet Finder could contain the first proof of a similar phenomenon on an ultracool, little M-dwarf star. Credit: NASA/SDO
Observations of a remote stellar flare might contain the very first proof of coronal rain on a cool, little M-dwarf star.
High-resolution spectroscopic observations of an excellent flare on a little, cool star suggest the possibility of coronal rain, a phenomenon that has actually been observed on our Sun but not yet verified on a star of this size. This faint star, called vB 10, which has to do with a tenth the size of the Sun and produces less than 1% of the Suns energy, was studied utilizing the Penn State Habitable-zone Planet Finder (HPF) at the big Hobby Eberly Telescope (with its 10 m mirror). These observations with the HPF spectrograph permitted scientists to determine a shift in the wavelength of specific atomic lines from the flare that follow hot plasma raining back down on the stars surface and are comparable to observations of coronal rain from the Sun.
A paper describing the observations, by a team led by Penn State researchers, includes a time-series analysis of the flare and might assist astronomers put restrictions on the energy and frequency of such events. The paper has been released in The Astrophysical Journal.
New high-resolution spectrographic observations of a flare on a faint distant star using the Penn State Habitable-zone Planet Finder might include the first evidence of a similar phenomenon on an ultracool, small M-dwarf star. High-resolution spectroscopic observations of an excellent flare on a little, cool star indicate the possibility of coronal rain, a phenomenon that has actually been observed on our Sun but not yet verified on a star of this size. These observations with the HPF spectrograph enabled researchers to determine a shift in the wavelength of particular atomic lines from the flare that are constant with hot plasma raining back down on the stars surface and are similar to observations of coronal rain from the Sun.
“Coronal rain occurs when some of the gas delighted by the flare falls back to the stars surface.” Flares are believed to result from the disturbance of magnetic fields, but we do not currently have a model for how magnetic fields are created on stars like vB 10,” stated Ramsey.
” As the name suggests, the Habitable-zone Planet Finder was developed to spot planets by searching for shifts in the light spectra from M-dwarf stars that arise from the star wobbling under the gravitational pull of orbiting worlds,” stated Larry Ramsey, teacher emeritus of astronomy and astrophysics at Penn State and an author of the paper. “But we understood from the start that we might find out more about outstanding activity from these spectra than we do about planets.”
The star is categorized as an “ultracool dwarf”– it is close in size to Jupiter– and is amongst the tiniest stars that can still fuse hydrogen to helium. It was observed by HPF as part of its regular, planet hunting operations but subsequent analysis revealed a substantial spike in the stars emissions constant with an excellent flare.
Red shift in helium lines a sign of “coronal rain” on an ultracool M-dwarf star. Credit: Shubham Kanodia, Penn State
Flares are short lived intense eruptions of energy on outstanding surface areas. Astronomers do not know exactly what triggers them, but the present best hypothesis is that when magnetic field lines on outstanding surfaces rupture and reconnect they release a lot of energy, a few of which is transformed to thermal energy which accelerates ions and electrons on the star to severe speeds. A few of the gas near the occasion hurries back towards the stars surface and some is shot out above the flare.
” Stellar flares are typical on M-dwarf stars,” said Shubham Kanodia, a college student at Penn State and lead author of the paper. “But because of the high-resolution of the HPF spectrograph, we had the ability to detect some uncommon characteristics in the spectra from this flare.”
HPF detected emission from several atoms that were thrilled to high energy states by the flare. In particular, emission lines from the atomic transitions of helium atoms revealed a small shift towards longer wavelengths, referred to as a “red shift.” This shift reveals that the ecstatic atoms that emitted this light, were falling towards the star with a velocity of about 70 kilometers per second.
” This red-shift in the helium lines is a sign of a phenomenon called coronal rain, which has actually been observed on the Sun for many years,” stated Kanodia. “Coronal rain occurs when some of the gas delighted by the flare falls back to the stars surface. Some previous studies have recommended the possibility of coronal rain on M-dwarf stars, however If our analysis is correct, this would be the very first quantitative observation of coronal rain on an ultracool dwarf and the first to utilize helium emission as an indicator.”
Observations of flares and coronal rain on M-dwarfs might assist astronomers to much better understand the physics of stars.
” Flares are believed to result from the interruption of magnetic fields, but we dont presently have a design for how electromagnetic fields are generated on stars like vB 10,” stated Ramsey. “Its remarkable to see the similarities in the information of activity in between stars like this and our Sun. Additional observations like this will hopefully help constrain designs that can start to describe this phenomenon.”
HPF, which was developed and constructed at Penn State and is installed on the Hobby-Eberly Telescope at the McDonald Observatory in Texas, is among the few high-resolution near-infrared huge spectrographs capable of spotting these types of signals from small, cool stars.
” Its crucial to keep in mind that we discover the red shift in helium lines in addition to other emission lines which recommend that they are associated with a flare,” stated Suvrath Mahadevan, teacher of astronomy and astrophysics at Penn State, principal private investigator of HPF, and an author of the paper. “We know that the magnetic structure of these stars can be extremely different to stars like our Sun, so seeing this comparable activity is exciting and will ideally lead to a much better understanding of stellar magnetism and activity.”
Reference: “High resolution near-infrared spectroscopy of a flare around the ultracool dwarf vB 10” by Shubham Kanodia, Lawrence W. Ramsey, Marissa Maney, Suvrath Mahadevan, Caleb I. Cañas, Joe P. Ninan, Andrew J. Monson, Adam F. Kowalski, Maximos C. Goumas, Gudmundur Stefansson, Chad F. Bender, William D. Cochran, Scott A. Diddams, Connor Fredrick, Samuel P. Halverson, Fred R. Hearty, Steven Janowiecki, Andrew J. Metcalf, Stephen C. Odewahn, Paul Robertson, Arpita Roy, Christian Schwab, Ryan C. Terrien, Accepted, The Astrophysical Journal.arXiv:2111.14647.
In addition to Ramsey, Kanodia, and Mahadevan the research study group consists of Marissa Maney, Caleb Cañas, Joe P. Ninan, Andrew Monson, Adam F. Kowalski, Maximos C. Goumas, Gudmundur Stefansson, Chad F. Bender, William D. Cochran, Scott A. Diddams, Connor Fredrick, Samuel Halverson, Fred Hearty, Steven Janowiecki, Andrew J. Metcalf, Stephen C. Odewahn, Paul Robertson, Arpita Roy, Christian Schwab, and Ryan C. Terrien.
Computations for this research study were performed on the Penn State Institute for Computational and Data Sciences Advanced CyberInfrastructure (ICDS-ACI), including the CyberLAMP cluster supported by the U.S. National Science Foundation. The Center for Exoplanets and Habitable Worlds is supported by Penn State, the Eberly College of Science, and the Pennsylvania Space Grant Consortium.
