Jens Kammerer

About me

Hey there! I am an astronomer working on the characterization of exoplanets and brown dwarfs. Using the largest ground- and space-based telescopes, I am studying the orbits and atmospheres of gas giant exoplanets to learn how these objects came into existence and how they evolve throughout time. For this purpose, we take direct images of young planetary systems in the near-infrared, where these objects glow bright from their remaining formation heat. However, such direct observations of exoplanets are very challenging because the thermal glow of the planets is more than ten thousand times fainter than the bright light of their host stars which are located nearby on the sky. By the way, the bright dot on the background image is our Earth imaged by the Voyager 1 spacecraft from a distance of about six billion kilometers and is a fairly well representation of how our images of exoplanets look like (the planets are only seen as small dots).

My current research focuses on the application of NASA's new flagship mission, the James Webb Space Telescope (JWST), which will be launched into space at the end of this year. This new space telescope which features a 6.5 meter large gold-coated primary mirror will enable observations of exoplanets at wavelengths that are inaccessible from the ground due to the atmosphere of the Earth. Moreover, JWST will be able to directly detect fainter and therefore less massive planets than ever before. I work on coronagraphy observations with JWST's NIRCam instrument as part of the GTO team, and I am also leading a GO calibration program aiming to use the kernel-phase high-resolution imaging technique with NIRCam and a GO science program that will use NIRISS aperture masking interferometry to characterize the atmosphere of the reddest known sub-stellar companion HD 206893 B in the L- and M-bands.

Apart from that, I am also involved with potential future missions that could, for the first time, directly detect and characterize the atmospheres of Earth-like exoplanets in both reflected and thermal light. To understand the capabilities of these future missions, it is important to predict how many and what kind of exoplanets they would be able to detect and I am working on such predictions for NASA's LUVOIR mission concept (a large UV/optical/infrared single-dish space telescope) and the European LIFE mission concept (a space-based formation-flying nulling interferometer operating in the mid-infrared).

Characterization of HD 206893 B

In this work, we study the orbit and atmosphere of the reddest known sub-stellar companion HD 206893 B by combining our new GRAVITY data with GPI, SPHERE, and NACO data from the literature. GRAVITY's exquisite astrometric precision reveals a possible misalignment between the orbit of HD 206893 B and the debris disk of the system and the observed spectrum supports sub-micron sized dust particles in the cool upper atmosphere causing the extreme color of HD 206893 B. However, future observations are required to determine whether HD 206893 B is a gas giant planet or a brown dwarf.

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Disk extinction in T Tauri triple system

In this work, we study the mid-infrared photometry of all three stars in the famous T Tauri triple system. To separate the tight southern binary star at 10 microns, we apply the kernel-phase high-resolution imaging technique. We find a decrease in the mid-infrared brightness of T Tauri Sb, consistent with a recent dimming observed in the near-infrared. This supports the hypothesis that T Tauri Sb has moved along its orbit behind the southern circumbinary disk and now suffers from increased dust extinction and confirms the presence of multiple misaligned disks in the young T Tauri system.

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Pushing GRAVITY to deeper contrasts

In this work, we improve the detection limits for faint companions of the GRAVITY instrument at ESO's Very Large Telescope Interferometer in the North of Chile. This is achieved by studying and modeling the correlated errors which affect GRAVITY. When using our error correlation model in the companion search process, we are able to find more than two times fainter companions if compared to when only considering uncorrelated errors. Moreover, the robustness of statistical 3-sigma detections increases tremendously and false positive detections become much rarer.

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Searching for young giant planets

In this work, we are searching for young gas giant exoplanets in the Taurus star-forming region (SFR). Forming planets in this extremely young region should be particularly bright and therefore easier to find than their older counterparts, but due to the larger distance of the Taurus SFR if compared to nearby moving group targets, we need to achieve a higher resolution to be able to resolve Solar System scales. This is achieved with the so-called kernel-phase technique, which can detect companions below the classical diffraction-limit of a telescope.

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Kernel-phase from the ground

In this work, we search for faint companions at close separations around a sample of 28 nearby field stars. For this purpose, we apply the kernel-phase technique to archival ground-based NACO data and detect two stellar companions at or below the classical diffraction-limit, one of which was previously unknown. We also develop detector linearity, bad pixel, and saturation correction and principal component calibration algorithms that are applicable to Fourier plane imaging techniques in general.

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Finding habitable extrasolar worlds with LIFE

In this work, we predict the number and properties of exoplanets that could be detected with a future space-based formation-flying nulling interferometer operating in the mid-infrared, such as the LIFE mission concept that we recently proposed for ESA's Voyage 2050 program. The mid-infrared wavelength regime is ideal to study the thermal emission of temperate Earth-like exoplanets and to characterize the composition of their atmospheres. With such a mission, we could find the first habitable planets outside our Solar System.