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Artist’s analysis of the calcium-rich supernova 2019ehk. Shown in orange is the calcium-rich product developed in the surge. Purple coloring represents gas shedded by the star right prior to the surge, which then produced intense X-ray emission when the product hit the supernova shockwave. Credit: Aaron M. Geller, Northwestern University IT
Called “calcium-rich supernovae,” these outstanding surges are so uncommon that astrophysicists have actually struggled to discover and consequently study them. The nature of these supernovae and their system for developing calcium, for that reason, have actually stayed evasive.
Now a Northwestern University-led group has actually possibly revealed the real nature of these uncommon, mystical occasions. For the very first time ever, the scientists analyzed a calcium-rich supernova, called SN 2019ehk, with X-ray imaging, offering an extraordinary peek into the star throughout the last month of its life and supreme surge.
The research study, that includes information from W. M. Keck Observatory on Maunakea in Hawaii, is released in the August 5, 2020 problem of The Astrophysical Journal.
The brand-new findings exposed that a calcium-rich supernova is a compact star that sheds an external layer of gas throughout the lasts of its life. When the star blows up, its matter hits the loose product because external shell, giving off intense X-rays. The total surge triggers extremely hot temperature levels and high pressure, driving a chain reaction that produces calcium.
Hubble Space Telescope picture of SN 2019ehk in its spiral host galaxy Messier 100. The supernova is determined in red. Credit: Charlie Kilpatrick, UC Santa Cruz
“These events are so few in number that we have never known what produced calcium-rich supernova,” stated lead author Wynn Jacobson-Galan, an NSF Graduate Research Fellow at Northwestern University. “By observing what this star did in its final month before it reached its critical, tumultuous end, we peered into a place previously unexplored, opening new avenues of study within transient science.”
“Before this event, we had indirect information about what calcium-rich supernovae might or might not be,” stated senior author Raffaella Margutti, an assistant teacher of physics and astronomy at Northwestern University and a member of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics). “Now, we can confidently rule out several possibilities.”
‘The Richest of the Rich’
While all calcium originates from stars, calcium-rich supernovae load the most effective punch. Typical stars develop percentages of calcium gradually through burning helium throughout their lives. Calcium-abundant supernovae, on the other hand, produce huge quantities of calcium within seconds.
“The explosion is trying to cool down,” Margutti described. “It wants to give away its energy, and calcium emission is an efficient way to do that.”
Using Keck Observatory’s Low Resolution Imaging Spectrometer (LRIS), the scientists found SN 2019ehk gave off one of the most calcium ever observed in a particular astrophysical occasion.
“The beautiful Keck spectrum revealed it wasn’t just calcium-rich,” Margutti stated. “It was the richest of the rich.”
Keck II Laser Guide Star. Credit: W. M. Keck Observatory
‘A Global Collaboration Was Ignited’
Amateur astronomer Joel Shepherd very first found the intense burst in April 2019 while utilizing his brand-new telescope to see Messier 100 (M100), a spiral nebula situated 55 million light years from Earth. After seeing an intense orange dot appear in the frame, he right away reported the discovery to the huge neighborhood.
“As soon as the world knew that there was a potential supernova in M100, a global collaboration was ignited,” Jacobson-Galan stated. “Every single country with a prominent telescope turned to look at this object.”
The worldwide follow-up operation moved so rapidly, the supernova was observed simply 10 hours after blowing up. Leading observatories such as NASA’s Swift Satellite, Lick Observatory, and Keck Observatory were amongst the telescopes activated to take a look at SN 2019ehk in optical wavelengths.
University of California Santa Barbara college student Daichi Hiramatsu was the very first to activate Swift to study SN 2019ehk in the X-ray and ultraviolet. The X-ray emission identified with Swift just remained for 5 days prior to entirely vanishing.
“In the world of transients, we have to discover things very, very fast before they fade,” Margutti stated. “Initially, no one was looking for X-rays. Daichi noticed something and alerted us to the strange appearance of what looked like X-rays. We looked at the images and realized something was there. It was much more luminous than anybody would have ever thought. There were no preexisting theories that predicted calcium-rich transients would be so luminous in X-ray wavelengths.”
Uncovering New Clues
SN 2019ehk’s short luminosity informed another a story about its nature. The Northwestern scientists think the star shed an external layer of gas in its last days. When the star took off, its product hit this external layer to produce an intense, energetic burst of X-rays.
“The luminosity tells us how much material the star shed and how close that material was to the star,” Jacobson-Galan stated. “In this case, the star lost a very small amount of material right before it exploded. That material was still nearby.”
Although the Hubble Space Telescope had actually been observing M100 for the past 25 years, the effective gadget never ever signed up the star — which was experiencing its last development — accountable for SN 2019ehk. The scientists utilized the Hubble images to take a look at the supernova website prior to the surge took place and state this is yet another idea to the star’s real nature.
“It was likely a white dwarf or extremely low-mass huge star,” Jacobson-Galan stated. “Both of those would be very faint.”
“Without this explosion, you wouldn’t know that anything was ever there,” Margutti included. “Not even Hubble could see it.”
More on this research study:
Reference: “SN2019ehk: A double-peaked Ca-rich transient with luminous X-ray emission and shock-ionized spectral features” by Wynn V. Jacobson-Galán, Raffaella Margutti, Charles D. Kilpatrick, Daichi Hiramatsu, Hagai Perets, David Khatami, Ryan J. Foley, John Raymond, Sung-Chul Yoon, Alexey Bobrick, Yossef Zenati, Lluís Galbany, Jennifer Andrews, Peter J. Brown, Régis Cartier, Deanne L. Coppejans, Georgios Dimitriadis, Matthew Dobson, Aprajita Hajela, D. Andrew Howell, Hanindyo Kuncarayakti, Danny Milisavljevic, Mohammed Rahman, César Rojas-Bravo, David J. Sand, Joel Shepherd, Stephen J. Smartt, Holland Stacey, Michael Stroh, Jonathan J. Swift, Giacomo Terreran, Jozsef Vinko, Xiaofeng Wang, Joseph P. Anderson, Edward A. Baron, Edo Berger, Peter K. Blanchard, Jamison Burke, David A. Coulter, Lindsay DeMarchi, James M. DerKacy, Christoffer Fremling, Sebastian Gomez, Mariusz Gromadzki, Griffin Hosseinzadeh, Daniel Kasen, Levente Kriskovics, Curtis McCully, Tomás E. Müller-Bravo, Matt Nicholl, András Ordasi, Craig Pellegrino, Anthony L. Piro, András Pál, Juanjuan Ren, Armin Rest, R. Michael Rich, Hanna Sai, Krisztián Sárneczky, Ken J. Shen, Philip Short, Matthew R. Siebert, Candice Stauffer, Róbert Szakáts, Xinhan Zhang, Jujia Zhang and Kaicheng Zhang, 5 August 2020, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ab9e66
About LRIS
The Low Resolution Imaging Spectrometer (LRIS) is an extremely flexible and ultra-sensitive visible-wavelength imager and spectrograph developed at the California Institute of Technology by a group led by Prof. Bev Oke and Prof. Judy Cohen and commissioned in 1993. Since then it has actually seen 2 significant upgrades to even more boost its abilities: the addition of a 2nd, blue arm enhanced for much shorter wavelengths of light and the setup of detectors that are far more delicate at the longest (red) wavelengths. Each arm is enhanced for the wavelengths it covers. This big variety of wavelength protection, integrated with the instrument’s high level of sensitivity, enables the research study of whatever from comets (which have intriguing functions in the ultraviolet part of the spectrum), to the blue light from star development, to the traffic signal of extremely far-off things. LRIS likewise tapes the spectra of as much as 50 things concurrently, specifically helpful for research studies of clusters of galaxies in the most far-off reaches, and earliest times, of deep space. LRIS was utilized in observing far-off supernovae by astronomers who got the Nobel Prize in Physics in 2011 for research study figuring out that deep space was accelerating in its growth.
About W. M. Keck Observatory
The W. M. Keck Observatory telescopes are amongst the most clinically efficient on Earth. The 2 10-meter optical/infrared telescopes on the top of Maunakea on the Island of Hawaii include a suite of sophisticated instruments consisting of imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems.
