Special FLASH Talks: Jacob Jencson (JHU/STScI) & Kishalay De (MIT)

Tuesday, 05 December 2023 2 p.m. — 3 p.m. MST

NOIRLab Main Conference Room

Jacob Jencson (JHU/STScI) & Kishalay De (MIT)

Jacob Jencson, JHU/STScI
Demystifying Unusual Infrared Transients with JWST Spectroscopy
In its final years, the Spitzer Space Telescope expanded our view of the dynamic infrared (IR) sky by revealing entirely new and emerging classes of IR transients. These transients are diverse and populate the luminosity “gap” between classical novae and the much more luminous supernovae. A class of events discovered by Spitzer, dubbed SPRITEs (eSPecially Red Intermediate-luminosity Transient Events), are so red that any associated optical emission is faint or completely absent. A leading hypothesis for the origin of some SPRITEs is a common-envelope ejection or stellar merger with rapid obscuration by dust formation, but direct confirmation of this idea has proved elusive. The key to unraveling the nature of these events is mid-IR spectroscopy, now available with JWST. I will present results from a JWST Cycle 1 GTO program that obtained NIRSpec and MIRI spectra (3-12 micron; PID 1240; PI M. Ressler) of a prototypical SPRITE in IC 342. Modeling of these IR spectra reveals the mass and composition of its dusty outflow, providing vital new clues on the origins of this enigmatic class.

Kishalay De, MIT
The transient mid-infrared sky unveiled with WISE: Revealing the enshrouded births, deaths and afterlives of stars
The growth of mass in stars and supermassive black holes (SMBHs) underpins every area of astrophysics. It is now becoming increasingly clear that short-lived transient outbursts caused by eruptive mass transfer episodes likely dominate their growth and evolution. Yet, direct observations remain severely limited either due to their intrinsically red emission, or absorption due to intervening dust and gas which make these phenomena invisible in optical/X-ray time domain surveys. In this talk, I will present the WISE transient pipeline -- a novel effort aimed at a systematic all-sky census of the dynamic mid-infrared sky using more than a decade of data from the NEOWISE space mission. Utilizing the highest spatial resolution images together with state-of-the art image subtraction algorithms, we have created a statistically complete sample of more than five million infrared transients in NEOWISE data. Embarking on a large ground-based follow-up program, I will present results from multi-wavelength characterization of the brightest mid-infrared transients, revealing i) a complete census of proto-stellar growth through transient outbursts, ii) a new class of dust obscured stellar mergers in low mass stars, iii) new insights into the fiery fates of close planetary systems, iv) missed tidal disruption events by SMBHs in nearby galaxies.