Supriya Chakrabarti

Presentation Title:

Development and Validation of High-Contrast Imaging and Spectroscopic Technologies

At the University of Massachusetts Lowell, we continue to develop and mature optical technologies necessary for next discoveries in astrophysics and space physics. For astrophysical studies our recent focus has been on direct imaging of exoplanets in reflected visible light. We are also developing imaging spectrographs for ground-based round-the-clock observations of faint emissions from the upper atmosphere that carries the signatures of complex photo-chemical processes. These activities started at Boston University where it involved both undergraduate and graduate students some of whom are now faculty members and are leading spaceflight missions.

We continue to improve the Technology Readiness Levels (TRLs) of coronagraphic imaging technologies for exoplanetary systems using two sounding rockets, called PICTURE and PICTURE-B, and two High-altitude balloons (PICTURE-C). Each of the experiments carried a telescope, a coronagraph aided by one or two Deformable Mirrors (DM) to suppress starlight to an acceptable level (the required planet-to-star raw contrast ratio of £ 10-8) and a pointing system approaching 10-3 arc-sec – the performance of the James Webb Space Telescope (JWST).

The 2022 PICTURE-C flight achieved a 1 milli-arcsecond fine pointing, first ever on a suborbital platform. It also demonstrated broadband (540 – 660 nm) contrast of 5 × 10-6 in a dark zone spanning 2.5 – 10.2 λ/D (0.50″ – 2.1″) from space – another first. These results demonstrated the suitability of high-altitude balloons and associated technologies for direct imaging of exoplanetary systems and their environments. We believe that it would be possible to simultaneously image nearby Jupiter-like exoplanets and their debris disks in reflected visible light from Ultra Long Duration Balloon (ULDB) platforms.

For airglow and auroral observations we have developed a series of long-slit imaging spectrographs that opened ground-based, round-the-clock observations. These faint upper atmospheric emissions are typically restricted to two weeks centered around the New Moon times, when the background signal from the sky is low enough to allow statistically significant measurements. The current instrument called, HiT&MIS, observed sky emissions and their morphology during the April 2024 total solar eclipse from North Hero, Vermont. The instrument’s field of view was pointed approximately 20º away from the location of totality and observed selected spectral ranges around OI 557.7 nm, OI 630.0 nm, Ha and Hb features. Since December 2024, HiT&MIS has been observing auroral emissions from Kiruna, Sweden.

In this talk I will provide an overview of these activities and describe our plans for future.