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Cornell Department of Astronomy and Space Sciences Colloquium

Thursday, October 29, 2020 at 4:00pm to 5:00pm

Virtual Event

"Why I Stopped Waiting for Someone Else to Map the Warm-hot Circumgalactic Medium"

Abstract: For over half a century, observational astrophysics has been eager to successfully detect and map the most massive baryonic component of galaxies: warm-hot phase coronal gas extending into the circumgalactic medium (CGM). Despite its importance to galaxy evolution, this phase of gas is entirely unmapped in the nearby universe. Morphological characteristics, such as the presence, size, and extent of filamentary or cloud-like structures, are impossible to
determine through pencil-beam absorption line studies. The evolution of galaxies relies heavily on the properties of gaseous halos, indicating an urgent need to map and measure these understudied regions. In the last decade, high-efficiency reflective coatings for UV optics have
undergone a renaissance with transformative improvements in reflectivity per bounce and overall coating stability in the extreme UV (EUV). Detector technology sensitive to EUV wavelengths has seen steady development of MicroChannel Plate (MCP) detector technology. In parallel with these advances in UV technology, SmallSat missions with serious science objectives—which did not exist a decade ago—have emerged as a promising platform for highimpact
science, an opportunity for more adventurous experiments and investigations. In this talk, I present Aspera (PI C. Vargas): an EUV SmallSat mission concept to detect and map warmhot phase gas emission in nearby galaxies for the first time. The Aspera mission was designed to target the O VI emission line doublet from highly ionized oxygen, located at ll=1032, 1038 Å rest frame. Aspera combines a simple spectroscopic optical design using recent advances in
highly-reflective EUV-coated optics with an advanced UV MCP detector to optimize throughput and sensitivity. Aspera will build multiple days of exposure time on each individual target to
ensure spectroscopic detection of O VI emission and produce 2D morphological maps and direct measurements of physical conditions such as kinematics. The Aspera concept is being developed for submission to the inaugural 2020 NASA Astrophysics Pioneers call on October 1, 2020.

Dial-In Information

The colloquia are held every Thursday afternoon 4-5 pm. The public is welcome. To view via Zoom, please contact Monica Carpenter ( or Jason Jennings ( for the link.

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Monica Carpenter

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Carlos Vargas

Speaker Affiliation

University of Arizona

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