Observations of supernova "SN 2016gkg" taken with the Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory. Credit: W.Zhenga/A. Filippenko (UC Berkeley)
Sequence
of combined images (negatives, so black corresponds to bright) obtained
by Víctor Buso as SN 2016gkg appears and brightens in the outskirts of
the spiral galaxy NGC 613. Labels indicate the time each image was
taken. The object steadily brightens for about 25 minutes, as shown
quantitatively in the
lower-right panel. Credit: V.Buso, M.Bersten, et al.
Supernova 2016gkg in spiral galaxy NGC 613; color image taken by a group of UC Santa Cruz
astronomers on Feb. 18, 2017, with the 1-meter Swope telescope. Credit: C. Kilpatrick (UC Santa Cruz) and Carnigie Institution for Science, Las Campanas Observatory, Chile
Co-author
Alex Filippenko, a UC Berkeley astronomer (right) with UC Santa Cruz
Assistant Professor Ryan Foley (left), both of whom are longtime W. M.
Keck Observatory users. Credit: © Laurie Hatch
Co-author
Alex Filippenko's team included undergraduate students at UC Berkeley
who helped research and monitor the changing brightness of Supernova
2016gkg. Credit: A. Filippenko
Maunakea, Hawaii –
Thanks to lucky snapshots taken by an amateur astronomer in Argentina,
scientists have obtained their first view of the initial burst of light
from the explosion of a massive star.
During tests of a new
camera, Víctor Buso captured images of a distant galaxy before and after
the supernova's "shock breakout" – when a supersonic pressure wave from
the exploding core of the star hits and heats gas at the star’s surface
to a very high temperature, causing it to emit light and rapidly
brighten.
To date, no one has been able to capture the "first
optical light" from a normal supernova (one not associated with a
gamma-ray or x-ray burst), since stars explode seemingly at random in
the sky and the light from shock breakout is fleeting. The new data
provide important clues to the physical structure of the star just
before its catastrophic demise and to the nature of the explosion
itself.
"Professional astronomers have long been searching for
such an event," said UC Berkeley astronomer Alex Filippenko, who
followed up the discovery with observations at the Lick and Keck
observatories that proved critical to a detailed analysis of explosion,
called SN 2016gkg. "Observations of stars in the first moments they
begin exploding provide information that cannot be directly obtained in
any other way."
"Buso’s data are exceptional," he added. "This is
an outstanding example of a partnership between amateur and
professional astronomers."
The discovery and results of follow-up observations from around the world will be published in the Feb. 22 issue of the journal Nature (and published online on Feb. 21).
On
Sept. 20, 2016, Buso of Rosario, Argentina, was testing a new camera on
his 16-inch telescope by taking a series of short-exposure photographs
of the spiral galaxy NGC 613, which is about 80 million light years from
Earth and located within the southern constellation Sculptor.
Luckily,
he examined these images immediately and noticed a faint point of light
quickly brightening near the end of a spiral arm that was not visible
in his first set of images.
Astronomer Melina Bersten and her
colleagues at the Instituto de Astrofísica de La Plata in Argentina soon
learned of the serendipitous discovery and realized that Buso had
caught a rare event, part of the first hour after light emerges from a
massive exploding star.
She estimated Buso's chances of such a
discovery, his first supernova, at one in 10 million or perhaps even as
low as one in 100 million.
“It’s like winning the cosmic lottery,” said Filippenko.
Bersten
immediately contacted an international group of astronomers to help
conduct additional frequent observations of SN 2016gkg over the next two
months, revealing more about the type of star that exploded and the
nature of the explosion.
Filippenko and his colleagues obtained a
series of seven spectra, where the light is broken up into its
component colors, as in a rainbow, with the Shane 3-meter telescope at
the University of California’s Lick Observatory near San Jose,
California.
The researchers also performed spectroscopic
observations using the Low Resolution Imaging Spectrometer (LRIS) and
the DEep Imaging and Multi-Object Spectrograph (DEIMOS) at W. M. Keck
Observatory on Maunakea, Hawaii.
The data allowed the
international team to determine that the explosion was a Type IIb
supernova: the explosion of a massive star that had previously lost most
of its hydrogen envelope, a species of exploding star first
observationally identified by Filippenko in 1987.
Combining the
data with theoretical models, the team estimated that the initial mass
of the star was about 20 times the mass of our sun, though it lost most
of its mass, probably to a companion star, and slimmed down to about
five solar masses prior to exploding.
Filippenko’s team continued
to monitor the supernova’s changing brightness over two months with
other Lick telescopes: the 0.76-meter Katzman Automatic Imaging
Telescope and the 1- meter Nickel telescope.
“The Lick spectra,
obtained with just a 3-meter telescope, are of outstanding quality in
part because of a recent major upgrade to the Kast spectrograph, made
possible by the Heising- Simons Foundation as well as William and Marina
Kast,” Filippenko said.
Filippenko’s group, which included
numerous undergraduate students, is supported by the Christopher R.
Redlich Fund, Gary and Cynthia Bengier, the TABASGO Foundation, the
Sylvia and Jim Katzman Foundation, many individual donors, the Miller
Institute for Basic Research in Science and NASA through the Space
Telescope Science Institute. Research at Lick Observatory is partially
supported by a generous gift from Google.
ve obtained their first view of the initial burst of light
from the explosion of a massive star.
During tests of a new
camera, Víctor Buso captured images of a distant galaxy before and after
the supernova's "shock breakout" – when a supersonic pressure wave from
the exploding core of the star hits and heats gas at the star’s surface
to a very high temperature, causing it to emit light and rapidly
brighten.
To date, no one has been able to capture the "first
optical light" from a normal supernova (one not associated with a
gamma-ray or x-ray burst), since stars explode seemingly at random in
the sky and the light from shock breakout is fleeting. The new data
provide important clues to the physical structure of the star just
before its catastrophic demise and to the nature of the explosion
itself.
"Professional astronomers have long been searching for
such an event," said UC Berkeley astronomer Alex Filippenko, who
followed up the discovery with observations at the Lick and Keck
observatories that proved critical to a detailed analysis of explosion,
called SN 2016gkg. "Observations of stars in the first moments they
begin exploding provide information that cannot be directly obtained in
any other way."
"Buso’s data are exceptional," he added. "This is
an outstanding example of a partnership between amateur and
professional astronomers."
The discovery and results of follow-up observations from around the world will be published in the Feb. 22 issue of the journal Nature (and published online on Feb. 21).
On
Sept. 20, 2016, Buso of Rosario, Argentina, was testing a new camera on
his 16-inch telescope by taking a series of short-exposure photographs
of the spiral galaxy NGC 613, which is about 80 million light years from
Earth and located within the southern constellation Sculptor.
Luckily,
he examined these images immediately and noticed a faint point of light
quickly brightening near the end of a spiral arm that was not visible
in his first set of images.
Astronomer Melina Bersten and her
colleagues at the Instituto de Astrofísica de La Plata in Argentina soon
learned of the serendipitous discovery and realized that Buso had
caught a rare event, part of the first hour after light emerges from a
massive exploding star.
She estimated Buso's chances of such a
discovery, his first supernova, at one in 10 million or perhaps even as
low as one in 100 million.
“It’s like winning the cosmic lottery,” said Filippenko.
Bersten
immediately contacted an international group of astronomers to help
conduct additional frequent observations of SN 2016gkg over the next two
months, revealing more about the type of star that exploded and the
nature of the explosion.
Filippenko and his colleagues obtained a
series of seven spectra, where the light is broken up into its
component colors, as in a rainbow, with the Shane 3-meter telescope at
the University of California’s Lick Observatory near San Jose,
California.
The researchers also performed spectroscopic
observations using the Low Resolution Imaging Spectrometer (LRIS) and
the DEep Imaging and Multi-Object Spectrograph (DEIMOS) at W. M. Keck
Observatory on Maunakea, Hawaii.
The data allowed the
international team to determine that the explosion was a Type IIb
supernova: the explosion of a massive star that had previously lost most
of its hydrogen envelope, a species of exploding star first
observationally identified by Filippenko in 1987.
Combining the
data with theoretical models, the team estimated that the initial mass
of the star was about 20 times the mass of our sun, though it lost most
of its mass, probably to a companion star, and slimmed down to about
five solar masses prior to exploding.
Filippenko’s team continued
to monitor the supernova’s changing brightness over two months with
other Lick telescopes: the 0.76-meter Katzman Automatic Imaging
Telescope and the 1- meter Nickel telescope.
“The Lick spectra,
obtained with just a 3-meter telescope, are of outstanding quality in
part because of a recent major upgrade to the Kast spectrograph, made
possible by the Heising- Simons Foundation as well as William and Marina
Kast,” Filippenko said.
Filippenko’s group, which included
numerous undergraduate students, is supported by the Christopher R.
Redlich Fund, Gary and Cynthia Bengier, the TABASGO Foundation, the
Sylvia and Jim Katzman Foundation, many individual donors, the Miller
Institute for Basic Research in Science and NASA through the Space
Telescope Science Institute. Research at Lick Observatory is partially
supported by a generous gift from Google.
About LRIS
The
Low Resolution Imaging Spectrometer (LRIS) is a faint-light instrument
capable of taking spectra and images of the most distant known objects
in the universe. The instrument is equipped with a red arm and a blue
arm to explore stellar populations of distant galaxies, active galactic
nuclei, galactic clusters, and quasars. LRIS was used in observing
distant supernovae by astronomers who received the Nobel Prize in
Physics in 2011 for research determining that the universe was speeding
up in its expansion. Support for LRIS was generously provided by Friends
of Keck, including Change Happens Foundation and Mt. Cuba Astronomical
Foundation.
About Deimos
The DEep Imaging
and Multi-Object Spectrograph (DEIMOS) boasts the largest field of view
(16.7arcmin by 5 arcmin) of any of the Keck Observatory instruments, and
the largest number of pixels (64 Mpix). It is used primarily in its
multi-object mode, obtaining simultaneous spectra of up to 130 galaxies
or stars. Astronomers study fields of distant galaxies with DEIMOS,
efficiently probing the most distant corners of the universe with high
sensitivity. Support for DEIMOS was generously provided by the National
Science Foundation.
About W.M. Keck Observatory
The
W. M. Keck Observatory telescopes are among the most scientifically
productive on Earth. The two, 10-meter optical/infrared telescopes on
the summit of Maunakea on the Island of Hawaii feature a suite of
advanced instruments including imagers, multi-object spectrographs,
high-resolution spectrographs, integral-field spectrometers, and
world-leading laser guide star adaptive optics systems.
The data
presented herein were obtained at Keck Observatory, which is a private
501(c) 3 non-profit organization operated as a scientific partnership
among the California Institute of Technology, the University of
California, and the National Aeronautics and Space Administration. The
Observatory was made possible by the generous financial support of the
W. M. Keck Foundation.
The authors wish to recognize and
acknowledge the very significant cultural role and reverence that the
summit of Maunakea has always had within the Native Hawaiian community.
We are most fortunate to have the opportunity to conduct observations
from this mountain.
Media Contact:
Mari-Ela Chock,
Communications Officer
mchock@keck.hawaii.edu
(808) 554-0567
Media Contact:
Mari-Ela Chock,
Communications Officer
mchock@keck.hawaii.edu
(808) 554-0567
Source: W.M. Keck Observatory
