Game Over for Supernovae Hide & Seek

SN 2013if with GeMS/GSAOI, from left to right with linear scaling: Reference image (June 2015), discovery image (April 2013) and the image subtraction. SN 2013if had a projected distance from the nucleus as small as 600 light years (200 pc), which makes it the second most nuclear CCSN discovery in a LIRG to date in the optical and near-IR after SN 2010cu.

The Core-collapse Supernova Rate Problem, or the fact that we don’t see as many core-collapse supernovae as we would expect, has a solution, thanks to research using the Gemini South telescope. The research team concludes that the majority of core collapse supernovae, exploding in luminous infrared galaxies, have previously not been found due to dust obscuration and poor spatial resolution. 
Core-collapse supernovae are spectacular explosions that mark the violent deaths of massive stars. An international team of astronomers, led by PhD student Erik Kool of Macquarie University in Australia, used laser guide star imaging on the Gemini South telescope to study why we don’t see as many of these core-collapse supernovae as expected. The study began in 2015 with the Supernova UNmasked By InfraRed detection (SUNBIRD) project which has shown that dust obscuration and limited spatial resolution can explain the small number of detections to date.
In this, the first results of the SUNBIRD project, the team discovered three core-collapse supernovae, and one possible supernova that could not be confirmed with subsequent imaging. Remarkably, these supernovae were spotted as close as 600 light years from the bright nuclear regions of these galaxies – despite being at least 150 million light years from the Earth. “Because we observed in the near-infrared, the supernovae are less affected by dust extinction compared to optical light,” said Kool.
According to Kool the results coming from SUNBIRD reveal that their new approach provides a powerful tool for uncovering core-collapse supernova in nuclear regions of galaxies. They also conclude that this methodology is crucial in characterizing these supernova that are invisible through other means. Kool adds, “The supernova rate problem can be resolved using the unique multi-conjugate adaptive optics capability provided by Gemini, which allows us to achieve the highest spatial resolution in order to probe very close to the nuclear regions of galaxies.” This work is published in the Monthly Notices of the Royal Astronomical Society.
This research is also highlighted in the January 2018 GeminiFocus (p.11).


Abstract: 

Core collapse supernova (CCSN) rates suffer from large uncertainties as many CCSNe exploding in regions of bright background emission and significant dust extinction remain unobserved. Such a shortfall is particularly prominent in luminous infrared galaxies (LIRGs), which have high star formation (and thus CCSN) rates and host bright and crowded nuclear regions, where large extinctions and reduced search detection efficiency likely lead to a significant fraction of CCSNe remaining undiscovered. We present the first results of project SUNBIRD (Supernovae UNmasked By InfraRed Detection), where we aim to uncover CCSNe that otherwise would remain hidden in the complex nuclear regions of LIRGs, and in this way improve the constraints on the fraction that is missed by optical seeing-limited surveys. We observe in the near-infrared 2.15 µm Ks-band, which is less affected by dust extinction compared to the optical, using the multi-conjugate adaptive optics imager GeMS/GSAOI on Gemini South, allowing us to achieve a spatial resolution that lets us probe close in to the nuclear regions. During our pilot program and subsequent first full year we have discovered three CCSNe and one candidate with projected nuclear offsets as small as 200 pc. When compared to the total sample of LIRG CCSNe discovered in the near-IR and optical, we show that our method is singularly effective in uncovering CCSNe in nuclear regions and we conclude that the majority of CCSNe exploding in LIRGs are not detected as a result of dust obscuration and poor spatial resolution.


What Stars Will Hatch From The Tarantula Nebula? NASA’s Flying Observatory Seeks to Find Out

The Tarantula Nebula as seen on SOFIA’s visible light guide camera during observations from Christchurch, New Zealand.
Credits: NASA/SOFIA/Nicholas A. Veronico

To have a full picture of the lives of massive stars, researchers need to study them in all stages – from when they’re a mass of unformed gas and dust, to their often dynamic end-of-life explosions.

NASA’s flying telescope, the Stratospheric Observatory for Infrared Astronomy, or SOFIA, is particularly well-suited for studying the pre-natal stage of stellar development in star-forming regions, such as the Tarantula Nebula, a giant mass of gas and dust located within the Large Magellanic Cloud, or LMC.  
Researchers from the Minnesota Institute for Astrophysics, led by Michael Gordon, went aboard SOFIA to identify and characterize the brightness, ages and dust content of three young star-forming regions within the LMC.
The Large Magellanic Cloud has always been an interesting and excellent laboratory for massive star formation,” said Gordon. “The chemical properties of star-forming regions in the LMC are significantly different than in the Milky Way, which means the stars forming there potentially mirror the conditions of star formation in dwarf galaxies at earlier times in the universe.”
In our galactic neighborhood, which includes the LMC, massive stars – generally classified as stars more than eight times the mass of Earth’s Sun – are believed to form exclusively in very dense molecular clouds. The dark dust and gas absorb background light, which prevents traditional optical telescopes from imaging these areas.
“The mid-infrared capabilities of SOFIA are ideal for piercing through infrared dark clouds to capture images of potential massive star-forming regions,” Gordon said.
The observations were completed with the Faint Object infrared Camera for the SOFIA Telescope, known as FORCAST. This infrared camera also performs spectroscopy, which identifies the elements present.
Astronomers study stars evolving in both the optical and the infrared to learn more about the photosphere, and the population of stars in the photosphere. The mid- and far-infrared data from SOFIA reaffirm dust temperature and mass accretion rates that are consistent with prior research of the LMC.
“We want to combine as many observations as we can from the optical, as seen through images from the Hubble Space Telescope, all the way out to the far infrared, imaged using the Spitzer Space Telescope and the Herschel Space Observatory, to get as broad a picture as possible,” Gordon continued. “No previous researchers have used FORCAST’s wavelength range to effectively study massive star formations. We needed SOFIA to fill in the 20- to 40-micron gap to give us the whole picture of what’s taking place.”
In summer 2017, further research of the Tarantula Nebula was accomplished aboard SOFIA during the observatory’s six-week science campaign operating from Christchurch, New Zealand, to study the sky in the Southern Hemisphere. Gordon and his team are hopeful that when analyzed, data obtained from the Christchurch flights will reveal previously undiscovered young massive stars forming in the region, which have never been observed outside of the Milky Way.
SOFIA is a Boeing 747SP jetliner modified to carry a 100-inch diameter telescope. It is a joint project of NASA and the German Aerospace Center, DLR. NASA’s Ames Research Center in California’s Silicon Valley manages the SOFIA program, science and mission operations in cooperation with the Universities Space Research Association headquartered in Columbia, Maryland, and the German SOFIA Institute (DSI) at the University of Stuttgart. The aircraft is based at NASA’s Armstrong Flight Research Center’s Hangar 703, in Palmdale, California.

Source: NASA/SOFIA


Media Point of Contact

Nicholas A. Veronico
NVeronico@sofia.usra.edu • SOFIA Science Center
NASA Ames Research Center, Moffett Field, California

Editor: Kassandra Bell