Tim Lichtenberg
@timlichtenberg.bsky.social
Assistant Professor of Planetary Physics at Kapteyn Astronomical Institute, University of Groningen 🇪🇺 he/him | formingworlds.space | born at 351 ppm
@kapteynastro.bsky.social of @rug.nl invites applications for in total 7 PhD and 4 ERC-funded postdoc positions in our annual call. ⭐🔭
PhD positions:
aas.org/jobregister/...
Postdoctoral positions:
aas.org/jobregister/...
#exoplanet #astronomy #geoscience 🧪🔭⭐
[Image credit: Mark A. Garlick.]
PhD positions:
aas.org/jobregister/...
Postdoctoral positions:
aas.org/jobregister/...
#exoplanet #astronomy #geoscience 🧪🔭⭐
[Image credit: Mark A. Garlick.]
October 16, 2025 at 7:40 PM
@kapteynastro.bsky.social of @rug.nl invites applications for in total 7 PhD and 4 ERC-funded postdoc positions in our annual call. ⭐🔭
PhD positions:
aas.org/jobregister/...
Postdoctoral positions:
aas.org/jobregister/...
#exoplanet #astronomy #geoscience 🧪🔭⭐
[Image credit: Mark A. Garlick.]
PhD positions:
aas.org/jobregister/...
Postdoctoral positions:
aas.org/jobregister/...
#exoplanet #astronomy #geoscience 🧪🔭⭐
[Image credit: Mark A. Garlick.]
w/ Oli Shorttle, @johannateske.bsky.social & Eliza Kempton we reviewed our current understanding and prospects for peaking on the inside of small #exoplanets in "Constraining exoplanet interiors using observations of their atmospheres": www.science.org/stoken/autho... & arxiv.org/abs/2510.08844 🔭🧪⚒️☄️
October 13, 2025 at 12:27 PM
w/ Oli Shorttle, @johannateske.bsky.social & Eliza Kempton we reviewed our current understanding and prospects for peaking on the inside of small #exoplanets in "Constraining exoplanet interiors using observations of their atmospheres": www.science.org/stoken/autho... & arxiv.org/abs/2510.08844 🔭🧪⚒️☄️
The concept considers *cumulative* XUV irradiation, Fig. 4 in the paper, and suggests that this XUV-induced escape turns planets above the "shoreline" in the plot attached into bare-rock planets. If additional variables/processes are required it loses its predictive power.
September 23, 2025 at 9:47 PM
The concept considers *cumulative* XUV irradiation, Fig. 4 in the paper, and suggests that this XUV-induced escape turns planets above the "shoreline" in the plot attached into bare-rock planets. If additional variables/processes are required it loses its predictive power.
Within the context of the interdisciplinary PRELIFE consortium me and Wim van Westrenen are advertising a joint PhD position on the surface water levels and atmospheric composition of the earliest Earth: www.formingworlds.space/phdposition2.... Deadline: 10th June. Please share! 🌋🌏🧬
May 14, 2025 at 3:51 PM
Within the context of the interdisciplinary PRELIFE consortium me and Wim van Westrenen are advertising a joint PhD position on the surface water levels and atmospheric composition of the earliest Earth: www.formingworlds.space/phdposition2.... Deadline: 10th June. Please share! 🌋🌏🧬
(2) For truly distinguishing between bare-rock and atmosphere-rich scenarios, we need to move to phase curve observations. You can see in this plot that phase curves can distinguish between bare rock (red) and atmosphere (turquoise, purple) scenarios. The regions in this plot do not fully overlap,
December 19, 2024 at 11:30 AM
(2) For truly distinguishing between bare-rock and atmosphere-rich scenarios, we need to move to phase curve observations. You can see in this plot that phase curves can distinguish between bare rock (red) and atmosphere (turquoise, purple) scenarios. The regions in this plot do not fully overlap,
This also relates to my previous thread from earlier this week: diverse atmospheric compositions can conceivably mimic atmosphere-free scenarios, as shown a few days ago by Nicholls+ (arxiv.org/abs/2412.11987).
December 19, 2024 at 11:30 AM
This also relates to my previous thread from earlier this week: diverse atmospheric compositions can conceivably mimic atmosphere-free scenarios, as shown a few days ago by Nicholls+ (arxiv.org/abs/2412.11987).
This has been nicely illustrated/confirmed this Monday by Ducrot+ (arxiv.org/abs/2412.11627) who show that the two known TRAPPIST-1 b eclipse points can (for example) be explained by a hazy atmosphere spectrum.
December 19, 2024 at 11:30 AM
This has been nicely illustrated/confirmed this Monday by Ducrot+ (arxiv.org/abs/2412.11627) who show that the two known TRAPPIST-1 b eclipse points can (for example) be explained by a hazy atmosphere spectrum.
You can see this in this plot. With 5(!) eclipses measured with MIRI, for none of the planets in this plot can bare-rock and atmospheric features be uniquely distinguished: the viable regions for the blue, green (w/ atmospheres), and red (bare rock) scenarios overlap nearly completely in this plot.
December 19, 2024 at 11:30 AM
You can see this in this plot. With 5(!) eclipses measured with MIRI, for none of the planets in this plot can bare-rock and atmospheric features be uniquely distinguished: the viable regions for the blue, green (w/ atmospheres), and red (bare rock) scenarios overlap nearly completely in this plot.
The spectral differences between planetary compositions are accessible for a wide range of current and upcoming astronomical facilities, enabling to probe the underlying geochemical properties ("redox state") of rocky exoplanets.
December 17, 2024 at 11:53 AM
The spectral differences between planetary compositions are accessible for a wide range of current and upcoming astronomical facilities, enabling to probe the underlying geochemical properties ("redox state") of rocky exoplanets.
(2) Magma ocean atmospheric properties are diverse and strongly related to the geochemical conditions of the underlying mantle. Harrison finds H2O, CO2 and SO2 as good probes for the underlying geochemical properties and amount of volatiles stored in the magma.
December 17, 2024 at 11:53 AM
(2) Magma ocean atmospheric properties are diverse and strongly related to the geochemical conditions of the underlying mantle. Harrison finds H2O, CO2 and SO2 as good probes for the underlying geochemical properties and amount of volatiles stored in the magma.
However, they do not prohibit the presence of a lower molten mantle, but enable both short-term and long-lived magma ocean phases. Magma ocean atmospheres are complex and the cooling path is a sensitive function of planetary volatile composition.
December 17, 2024 at 11:53 AM
However, they do not prohibit the presence of a lower molten mantle, but enable both short-term and long-lived magma ocean phases. Magma ocean atmospheres are complex and the cooling path is a sensitive function of planetary volatile composition.
(1) There have been recent suggestions that steam atmospheres are not convective, which may inhibit the presence of magma oceans at their surfaces. Harrison finds that indeed radiative layers appear across a large range of compositions.
December 17, 2024 at 11:53 AM
(1) There have been recent suggestions that steam atmospheres are not convective, which may inhibit the presence of magma oceans at their surfaces. Harrison finds that indeed radiative layers appear across a large range of compositions.
Finally, and this is the most impactful result from an exoplanet perspective: fluid-driven tidal dissipation efficiently keeps exoplanet in permanent magma ocean phases! The attached plot shows a comparison for equilibria w/ and w/o fluid-driven dissipation.
December 11, 2024 at 10:26 AM
Finally, and this is the most impactful result from an exoplanet perspective: fluid-driven tidal dissipation efficiently keeps exoplanet in permanent magma ocean phases! The attached plot shows a comparison for equilibria w/ and w/o fluid-driven dissipation.
Second, close-in exoplanets reach spin-orbit synchronisation *much* faster than is typically thought, on Myr(!) timescales instead of Gyr timescales. Essentially immediately. Many of the known ultra-short period super-Earths are in this regime, which means that strong tidal-locking can occur.
December 11, 2024 at 10:26 AM
Second, close-in exoplanets reach spin-orbit synchronisation *much* faster than is typically thought, on Myr(!) timescales instead of Gyr timescales. Essentially immediately. Many of the known ultra-short period super-Earths are in this regime, which means that strong tidal-locking can occur.
Energy dissipation in a rapidly spinning protoplanets (like the Earthy Earth after the Moon-forming giant impact) is much more efficient than previously thought. If the atmosphere is not providing very efficient blanketing, this leads to rapid lunar recession on <100k yr.
December 11, 2024 at 10:26 AM
Energy dissipation in a rapidly spinning protoplanets (like the Earthy Earth after the Moon-forming giant impact) is much more efficient than previously thought. If the atmosphere is not providing very efficient blanketing, this leads to rapid lunar recession on <100k yr.
Typically tidal models only consider dissipation in the solid; liquid layers are not thought to contribute. However, it turns out that for specific rotation periods, the magma ocean dominates dissipation. This is driven by friction between the magma and the underlying solidified mantle.
December 11, 2024 at 10:26 AM
Typically tidal models only consider dissipation in the solid; liquid layers are not thought to contribute. However, it turns out that for specific rotation periods, the magma ocean dominates dissipation. This is driven by friction between the magma and the underlying solidified mantle.
Exciting new paper by Mohammad Farhat yesterday on arXiv: "Tides on Lava Worlds: Application to Close-in Exoplanets and the Early Earth-Moon System", by Mohammad Farhat, Pierre Auclair-Desrotour, Gwenaël Boué, Tim Lichtenberg, Jacques Laskar (arxiv.org/abs/2412.07285). 🥳🤯
December 11, 2024 at 10:26 AM
Exciting new paper by Mohammad Farhat yesterday on arXiv: "Tides on Lava Worlds: Application to Close-in Exoplanets and the Early Earth-Moon System", by Mohammad Farhat, Pierre Auclair-Desrotour, Gwenaël Boué, Tim Lichtenberg, Jacques Laskar (arxiv.org/abs/2412.07285). 🥳🤯
This is great news for using exoplanets surveys to better understand the chemical and physical conditions that may enable prebiotic chemistry on other worlds, and by that give us further clues on the prevalent conditions to kickstart life as we know it – also on our own planet!
October 18, 2024 at 7:48 AM
This is great news for using exoplanets surveys to better understand the chemical and physical conditions that may enable prebiotic chemistry on other worlds, and by that give us further clues on the prevalent conditions to kickstart life as we know it – also on our own planet!
He found that the intrinsic heat of transient magma ocean epochs make these planets detectable (and characterisable!) to vast distances (up to ~100 pc). LIFE will be able to find them typically within minutes in both G and M dwarf systems in young stellar associations.
October 18, 2024 at 7:47 AM
He found that the intrinsic heat of transient magma ocean epochs make these planets detectable (and characterisable!) to vast distances (up to ~100 pc). LIFE will be able to find them typically within minutes in both G and M dwarf systems in young stellar associations.
In a magma ocean phase rocky planets glow strongly – they are still hot and molten from the primordial heat of formation – and Lorenzo quantified how much of an advantage this is when searching for these planets.
October 18, 2024 at 7:47 AM
In a magma ocean phase rocky planets glow strongly – they are still hot and molten from the primordial heat of formation – and Lorenzo quantified how much of an advantage this is when searching for these planets.