The Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian

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Sebastian Zieba

Center for Astrophysics

NASA Sagan Fellow

Sebastian Zieba

sebastian.zieba@cfa.harvard.edu

About

Sebastian uses space telescopes to push the boundary of atmospheric characterization down to small, rocky exoplanets. He works with data collected by facilities such as the Spitzer Space Telescope, Hubble Space Telescope, and James Webb Space Telescope (JWST) to study worlds across an extensive temperature range, from “lava worlds” with outgassed rock-vapor atmospheres caused by scorching temperatures exceeding 2000 Kelvin, to terrestrial planets with temperatures around 400 Kelvin, more comparable to our own inner solar system.
As Principal Investigator (PI) and co-Investigator (co-I) of several JWST proposals, Sebastian studies the surfaces of hot, airless planets, measures their surface roughness, and explores the transition region between rocky and gaseous planets. Through these observations, he seeks to unravel the geological history of rocky exoplanets and identifies the conditions under which these small worlds can retain atmospheres.
Sebastian grew up in Salzburg, Austria. He earned his bachelor’s degree in physics from the University of Innsbruck in 2017. He remained in Innsbruck to pursue his master’s degree, during which he discovered transiting comets orbiting the exoplanet host star Beta Pictoris. After completing his master’s degree in 2020, he moved to Heidelberg, Germany, to pursue a doctorate in astronomy through a joint program with Leiden Observatory, earning his PhD cum laude in 2024. As part of this PhD research, he led the characterization of the lava world K2-141 b and of the temperate planet TRAPPIST-1 c, demonstrating the power of space-based infrared observations to probe diverse planetary properties. He is currently a NASA Sagan Fellow at the Center for Astrophysics.

Personal website: https://sebastian-zieba.github.io/

PhD - Max-Planck Institute for Astronomy (MPIA), Heidelberg, Germany & Leiden Observatory, Leiden, the Netherlands (2024), MSc Physics - Leopold Franzens University, Innsbruck, Austria (2020), BSc Physics - Leopold Franzens University, Innsbruck, Austria (2017)

Telescopes and Instruments

Kepler/K2

Since the early 1990s, astronomers have identified thousands of planets orbiting other stars. Most of those identifications have come thanks to one observatory: NASA’s Kepler space telescope. Until it lost its ability to point, Kepler observed a region of the sky containing about 150,000 stars with potential planets, monitoring them for the slight decrease in light caused by planets crossing in front of the star. After the spacecraft’s pointing control failed, the mission was renamed K2, and it continued to hunt for exoplanets as it tumbled slowly, with its field of view drifting slowly across the sky. The mission finally ended in 2018, though the data it produced continues to provide astronomers with valuable information about planets in our galactic neighborhood. Astronomers from the Center for Astrophysics | Harvard & Smithsonian were responsible for the preparation of the catalog for potentially interesting stars, and have participated extensively in follow-up observations of Kepler planetary discoveries.

Visit the Kepler/K2 Website

Spitzer Space Telescope

Infrared light is the key to studying a wide range of astronomical systems, including newborn stars and planets, dust in distant galaxies, and material swirling around black holes. The Spitzer Space Telescope was NASA’s orbiting infrared observatory, and part of NASA’s Great Observatories program, along with the Chandra X-ray Observatory and the Hubble Space Telescope. Scientists and engineers at the Center for Astrophysics | Harvard & Smithsonian led the design, testing, and construction of the Infrared Array Camera (IRAC). The Spitzer Space Telescope was launched in 2003 and retired in 2020.

Visit the Spitzer Space Telescope IRAC Page

Transiting Exoplanet Survey Satellite (TESS)

Astronomers have discovered thousands of planets orbiting other stars. Extrapolating from that knowledge, the Milky Way alone is probably home to hundreds of billions of planets, many of which are likely rocky, Earth-like worlds. NASA’s Transiting Exoplanet Survey Satellite (TESS) is a space observatory designed to look for exoplanets in orbit around 200,000 nearby bright stars, with a particular interest in identifying small planets. Astronomers from the Center for Astrophysics | Harvard & Smithsonian are part of the scientific team to analyze TESS data, as well as performing follow-up observations. The relative closeness of worlds in the TESS survey will allow astronomers to even study some of their atmospheres, using the future Giant Magellan Telescope (GMT) and other observatories. TESS observational program is complementary to NASA’s long-running Kepler/K2 mission, and could identify as many as 20,000 new exoplanet orbiting a wide variety of star types.

Visit the TESS Website