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Hubble Captures a Cosmic Cloudscape

Astronomy News - Sat, 15/02/2025 - 09:20
Explore Hubble

2 min read

Hubble Captures a Cosmic Cloudscape This NASA/ESA Hubble Space Telescope reveals clouds of gas and dust near the Tarantula Nebula, located in the Large Magellanic Cloud about 160,000 light-years away.ESA/Hubble & NASA, C. Murray Download this image

The universe is a dusty place, as this NASA/ESA Hubble Space Telescope image featuring swirling clouds of gas and dust near the Tarantula Nebula reveals. Located in the Large Magellanic Cloud about 160,000 light-years away in the constellations Dorado and Mensa, the Tarantula Nebula is the most productive star-forming region in the nearby universe, home to the most massive stars known.

The nebula’s colorful gas clouds hold wispy tendrils and dark clumps of dust. This dust is different from ordinary household dust, which may include of bits of soil, skin cells, hair, and even plastic. Cosmic dust is often comprised of carbon or of molecules called silicates, which contain silicon and oxygen. The data in this image was part of an observing program that aims to characterize the properties of cosmic dust in the Large Magellanic Cloud and other nearby galaxies.

Dust plays several important roles in the universe. Even though individual dust grains are incredibly tiny, far smaller than the width of a single human hair, dust grains in disks around young stars clump together to form larger grains and eventually planets. Dust also helps cool clouds of gas so that they can condense into new stars. Dust even plays a role in making new molecules in interstellar space, providing a venue for individual atoms to find each other and bond together in the vastness of space.

Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Explore More Caldwell 103 / Tarantula Nebula / 30 Doradus Hubble Studies the Tarantula Nebula’s Outskirts Hubble’s New View of the Tarantula Nebula Hubble’s Bubbles in the Tarantula Nebula Hubble Probes Interior of Tarantula Nebula

Media Contact:

Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight CenterGreenbelt, MD

Share Details Last Updated Feb 14, 2025 EditorAndrea GianopoulosLocationNASA Goddard Space Flight Center Related Terms Keep Exploring Discover More Topics From Hubble Hubble Space Telescope

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Fri 21 Feb 11:30: Galactic Archaelogy in the Gaia era: a surprising population of very metal-poor stars in the Milky Way disc

IoA Institute of Astronomy Talk Lists - Fri, 14/02/2025 - 14:28
Galactic Archaelogy in the Gaia era: a surprising population of very metal-poor stars in the Milky Way disc

The history of the Universe can be revealed in the light of the stars, in particular in the oldest and the most pristine, also called metal-poor stars. From the chemical composition of these stars, it is possible to unveil the fossil fingerprint left from the previous generations of stars and open a window on the early Universe and the origins of the elements. Moreover, the kinematical properties of the most metal-poor stars are informative on the assembly of the Milky Way and the first structures in the Universe. In this seminar, I will focus on why/where to/how to investigate the most metal-poor stars. I will discuss some of the major achievements of one of the most efficient surveys that hunts for these old stars, the Pristine survey. Then, I will focus on a particular population of very metal-poor stars that surprisingly inhabit the Milky Way plane. I will discuss how this population is connected to the early formation and evolution of our Galaxy.

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Tiny dwarf galaxy might house a supermassive black hole

Astronomy News - Fri, 14/02/2025 - 12:49

Fast-moving stars zooming through our galaxy might have been slingshotted from a black hole inside the neighbouring Large Magellanic Cloud

Bullseye! Galaxy hosts a record-breaking nine starry rings

Astronomy News - Fri, 14/02/2025 - 12:46

Nature, Published online: 13 February 2025; doi:10.1038/d41586-025-00399-3

Astronomers trace the striking pattern to an encounter between a big galaxy and a much smaller one some 50 million years ago.

NASA’s SPHEREx Space Telescope Will Seek Life’s Ingredients

Astronomy News - Fri, 14/02/2025 - 12:46

5 min read

Preparations for Next Moonwalk Simulations Underway (and Underwater) NASA’s SPHEREx mission will survey the Milky Way galaxy looking for water ice and other key ingredients for life. In the search for these frozen compounds, the mission will focus on molecular clouds — collections of gas and dust in space — like this one imaged by the agency’s James Webb Space Telescope. NASA, ESA, CSA

Where is all the water that may form oceans on distant planets and moons? The SPHEREx astrophysics mission will search the galaxy and take stock.

Every living organism on Earth needs water to survive, so scientists searching for life outside our solar system, are often guided by the phrase “follow the water.” Scheduled to launch no earlier than Thursday, Feb. 27, NASA’s SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) mission will help in that quest.

After its ride aboard a SpaceX Falcon 9 from Vandenberg Space Force base in California, the observatory will search for water, carbon dioxide, carbon monoxide, and other key ingredients for life frozen on the surface of interstellar dust grains in the clouds of gas and dust where planets and stars eventually form.

While there are no oceans or lakes floating freely in space, scientists think these reservoirs of ice, bound to small dust grains, are where most of the water in our universe forms and resides. Additionally, the water in Earth’s oceans as well as those of other planets and moons in our galaxy likely originated in such locations.

The Perseus Molecular Cloud, located about 1,000 light-years from Earth, was imaged by NASA’s retired Spitzer Space Telescope. NASA’s SPHEREx mission will search the galaxy for water ice and other frozen compounds in clouds of gas and dust in space like this one. NASA/JPL-Caltech

The mission will focus on massive regions of gas and dust called molecular clouds. Within those, SPHEREx will also look at some newly formed stars and the disks of material around them from which new planets are born.

Although space telescopes such as NASA’s James Webb and retired Spitzer have detected water, carbon dioxide, carbon monoxide, and other compounds in hundreds of targets, the SPHEREx observatory is the first to be uniquely equipped to conduct a large-scale survey of the galaxy in search of water ice and other frozen compounds.

Get the SPHEREx Press Kit

Rather than taking 2D images of a target like a star, SPHEREx will gather 3D data along its line of sight. That enables scientists to see the amount of ice present in a molecular cloud and observe how the composition of the ices throughout the cloud changes in different environments.

By making more than 9 million of these line-of-sight observations and creating the largest-ever survey of these materials, the mission will help scientists better understand how these compounds form on dust grains and how different environments can influence their abundance.  

Tip of the Iceberg

It makes sense that the composition of planets and stars would reflect the molecular clouds they formed in. However, researchers are still working to confirm the specifics of the planet formation process, and the universe doesn’t always match scientists’ expectations.

For example, a NASA mission launched in 1998, the Submillimeter Wave Astronomy Satellite (SWAS), surveyed the galaxy for water in gas form — including in molecular clouds — but found far less than expected.

BAE Systems employees work on NASA’s SPHEREx observatory in the Astrotech Space Operations facility at Vandenberg Space Force Base in California on Jan. 16. Targeting a Feb. 27 launch, the mission will map the entire sky in infrared light. NASA/JPL-Caltech

“This puzzled us for a while,” said Gary Melnick, a senior astronomer at the Center for Astrophysics | Harvard & Smithsonian and a member of the SPHEREx science team. “We eventually realized that SWAS had detected gaseous water in thin layers near the surface of molecular clouds, suggesting that there might be a lot more water inside the clouds, locked up as ice.”

The mission team’s hypothesis also made sense because SWAS detected less oxygen gas (two oxygen atoms bound together) than expected. They concluded that the oxygen atoms were sticking to interstellar dust grains, and were then joined by hydrogen atoms, forming water. Later research confirmed this. What’s more, the clouds shield molecules from cosmic radiation that would otherwise break those compounds apart. As a result, water ice and other materials stored deep in a cloud’s interior are protected.

As starlight passes through a molecular cloud, molecules like water and carbon dioxide block certain wavelengths of light, creating a distinct signature that SPHEREx and other missions like Webb can identify using a technique called absorption spectroscopy.

In addition to providing a more detailed accounting of the abundance of these frozen compounds, SPHEREx will help researchers answer questions including how deep into molecular clouds ice begins to form, how the abundance of water and other ices changes with the density of a molecular cloud, and how that abundance changes once a star forms.

Powerful Partnerships

As a survey telescope, SPHEREx is designed to study large portions of the sky relatively quickly, and its results can be used in conjunction with data from targeted telescopes like Webb, which observe a significantly smaller area but can see their targets in greater detail.

“If SPHEREx discovers a particularly intriguing location, Webb can study that target with higher spectral resolving power and in wavelengths that SPHEREx cannot detect,” said Melnick. “These two telescopes could form a highly effective partnership.”

More About SPHEREx

SPHEREx is managed by NASA’s Jet Propulsion Laboratory in Southern California for the Astrophysics Division within the Science Mission Directorate at NASA Headquarters in Washington. BAE Systems (formerly Ball Aerospace) built the telescope and the spacecraft bus. The science analysis of the SPHEREx data will be conducted by a team of scientists located at 10 institutions in the U.S., two in South Korea, and one in Taiwan. Data will be processed and archived at IPAC at Caltech, which manages JPL for NASA. The mission principal investigator is based at Caltech with a joint JPL appointment. The SPHEREx dataset will be publicly available at the NASA/IPAC Infrared Science Archive.

For more information about the SPHEREx mission visit:

https://www.jpl.nasa.gov/missions/spherex/

6 Things to Know About SPHEREx Why NASA’s SPHEREx Mission Will Make ‘Most Colorful’ Cosmic Map Ever News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
626-808-2469
calla.e.cofield@jpl.nasa.gov

2025-020

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Tue 25 Feb 11:15: Exoplanet Detection with SPIRIT: Infrared CMOS Photometry and the Discovery of the Hot Neptune TOI-2407b

Next External Talks - Fri, 14/02/2025 - 10:06
Exoplanet Detection with SPIRIT: Infrared CMOS Photometry and the Discovery of the Hot Neptune TOI-2407b

The SPECULOOS project is dedicated to the discovery of transiting exoplanets around ultracool dwarfs using high-precision ground-based observations. To enhance sensitivity to these cool stars, we have implemented SPIRIT , a new infrared detector utilizing CMOS technology instead of traditional CCDs. In this talk, I will present my work on developing the data pipeline for SPIRIT and optimizing its performance for detecting exoplanet transits. I will also highlight the discovery of TOI -2407b, a Neptune-like planet observed with this system.

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Categories: Talks

Mon 24 Feb 13:00: Total derivatives in cosmological perturbations: implications for decoherence and Bell violation

Next External Talks - Fri, 14/02/2025 - 08:26
Total derivatives in cosmological perturbations: implications for decoherence and Bell violation

We examine the role of total time derivatives (boundary terms) in the action of cosmological perturbations and their impact on momentum-space entanglement, including the processes of decoherence and two-mode squeezing. We also discuss the necessity of considering such terms from several perspectives: the well-defined variational principle in gravity, the integration-by-parts procedure in cosmological perturbations and the WKB limit of the Wheeler-DeWitt equation. Finally, we explore their relevance in a proposed cosmological Bell test utilizing momentum-space entanglement, suggesting a possible window for Bell violation in minimal single-field inflation.

References: 2405.07141, 2305.08071 and 2207.04435

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Categories: Talks

Executive Assistant and Project Coordinator (Fixed Term)

Vacancies - Fri, 14/02/2025 - 00:00

Fixed-term: The funds for this post are available for 2 years in the first instance.

We are seeking a highly skilled and experienced Executive Assistant and Project Coordinator to join the prestigious Institute of Astronomy (IoA). You will play a pivotal role in supporting Professor Richard McMahon (Professor of Astronomy).

The key purpose of this role is to coordinate, implement and oversee administrative procedures for the efficient running of the office of Principal Investigator (PI) Professor Richard McMahon (Professor of Astronomy) at the Institute of Astronomy, University of Cambridge.

The ideal candidate will possess a degree or equivalent qualification and demonstrate practical experience in supporting programme delivery, preferably within a higher education environment. Exceptional communication, organisational, and planning skills are essential for success in this role, as is the ability to work collaboratively within a team.

For detailed information regarding the required skills, experience, and knowledge for this role, please refer to the further information link provided below.

This position offers a competitive salary at Grade 6 (£33,232 - £39,105) full time equivalent per annum, commensurate with the applicant's level of expertise and experience. Please note that salary will be pro rata dependent on the part time hours agreed. In addition, working at the University of Cambridge presents numerous benefits, including:

A supportive and inclusive work environment that fosters collaboration and prioritizes employee well-being

Competitive compensation with automatic service-related pay progression and annual cost of living increases

Generous annual leave entitlement of 36 days, inclusive of bank holidays, for full-time employees (pro rata'd for part-time employees)

Extensive maternity, adoption, and shared parental leave entitlement, along with other family-friendly schemes such as workplace nurseries and salary exchange schemes for childcare

Auto-enrolment pension scheme with a generous employer contribution

Travel benefits and retail discounts at over 2,000 local and national stores

Regular meetings with your line manager and an annual development review to support your personal growth

Provision of IT equipment to enable hybrid working, where feasible

Access to University training courses for continuous learning and development opportunities

This is a part-time, fixed term position with funding available for 2 years in the first instance, with the possibility of further extension subject to funding. The position will be between 06 to 0.8 full time equivalent, with weekly working hours to be between 21 hours 54 minutes to 29 hours 12 minutes per week, with exact working pattern and working hours to be discussed during the recruitment process.

The Institute of Astronomy is located at the University of Cambridge on Madingley Road, Cambridge, CB3 0HA.

We welcome applications from individuals who wish to be considered for flexible working arrangements.

Click the 'Apply' button below to register an account with our recruitment system (if you have not already) and apply online.

Please complete the application in full, including giving details of 2 referees, which are essential. Please advise referees that where you agree to our contacting referees in advance, references will be requested before the interview week, such contact will be to your referees via our recruitment system.

The closing date for applications is: 23:59 GMT on Thursday 27th February 2025.

Applications will be reviewed after the closing date, and short-listed candidates will be interviewed shortly afterwards.

The post holder will ideally start in March 2025.

We welcome informal inquiries, which can be directed via email to Angela Macharia at departmental.administrator@ast.cam.ac.uk . If you have any questions regarding the application process, please contact HR@ast.cam.ac.uk .

Please quote reference LG44886 on your application and in any correspondence about this vacancy.

The University actively supports equality, diversity and inclusion and encourages applications from all sections of society.

The University has a responsibility to ensure that all employees are eligible to live and work in the UK.

Tue 18 Feb 13:00: TOI-2407b: A hot Neptune in the Neptune Desert discovered with the SPIRIT Infrared Detector

IoA Institute of Astronomy Talk Lists - Thu, 13/02/2025 - 19:34
TOI-2407b: A hot Neptune in the Neptune Desert discovered with the SPIRIT Infrared Detector

The discovery and characterization of exoplanets around ultracool dwarfs require precise ground-based observations across visible and infrared wavelengths. In this talk, I will present the discovery of TOI -2407b, a Neptune-sized planet located in the Neptune desert—a sparsely populated region of parameter space for close-in exoplanets. This detection was made using SPIRIT , a novel infrared CMOS detector designed to enhance sensitivity to cool stars. I will discuss the role of SPIRIT in improving exoplanet transit observations, the development of its data pipeline, and the implications of TOI -2407b for our understanding of planet formation and evolution in the Neptune desert.

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Fri 21 Feb 13:00: Free conformally-rescaled hyperboloidal evolution: status and applications

Next External Talks - Thu, 13/02/2025 - 18:36
Free conformally-rescaled hyperboloidal evolution: status and applications

Gravitational wave radiation is only unambiguously defined at future null infinity – the location in spacetime where light rays arrive and where global properties of spacetimes can be measured. Reaching future null infinity is thus very important for extracting correct waveforms. A convenient way to include it in numerical relativity simulations is via hyperboloidal foliations. I will focus on conformal compactification as method to implement free hyperboloidal evolution, in the BSSN / conformal Z4 formulations. After illustrating its advantages, I will report on some ongoing applications in spherical symmetry: an extension to include the Maxwell equations, scattering simulations on a given background, and wave equation(s) evolved on some FLRW -type spacetimes with time-dependent scale factor. I will conclude giving an update on ongoing work in 3D evolutions.

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Categories: Talks

Fri 09 May 11:30: Title to be confirmed

IoA Institute of Astronomy Talk Lists - Thu, 13/02/2025 - 12:43
Title to be confirmed

Abstract not available

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Fri 28 Feb 14:30: Mauve: a UV-Vis small satellite dedicated to monitor stellar activity and variability

IoA Institute of Astronomy Talk Lists - Thu, 13/02/2025 - 11:59
Mauve: a UV-Vis small satellite dedicated to monitor stellar activity and variability

Mauve is a small satellite equipped with a 13-cm telescope and a UV-Visible spectrometer (with an operative wavelength range of 200-700 nm) conceived to measure the stellar magnetic activity and variability. The satellite and science program will be delivered by Blue Skies Space via a multi-year collaborative survey program, with thousands of hours each year available for long baseline observations of hundreds of stars, unlocking a significant time domain astronomy opportunity. Mauve’s mission lifetime is 3 years with the ambition of 5 years, and will cover a broad field of regard (–46.4 to 31.8 degrees in ICRS ) during this period.

This facility was conceived to support pilot studies and new ideas in science and is fully dedicated to time-domain astronomy. The main surveys to be executed by Mauve are long baseline observations of flare stars, Herbig Ae/Be stars, exoplanet hosts, as well as contact binary variables (RS CVn variables, symbiotic stars, Algol-type stars, etc.). Besides these major science themes, the spectrometer’s data can be utilized to support and complement existing and upcoming facilities as a pathfinder, or conduct simultaneous/follow-up observations.

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Tue 04 Mar 11:15: Cygnus X-3 in 2024: many giant radio flares!

Next External Talks - Thu, 13/02/2025 - 11:34
Cygnus X-3 in 2024: many giant radio flares!

Cygnus X-3 is a `high mass X-ray binary’, which was first detected in the early days of X-ray astronomy, in 1966. It is also seen in the radio and the infra-red (but not optically due to obscuration). The emission is due to accretion from the companion star onto the compact source, thought to be a Wolf-Rayet star and a black hole respectively. It occasionally shows giant fares, and has been monitored—approximately daily—for several years with the Arcminute Microkelvin Image (AMI) at Lord’s Bridge, SW of Cambridge. During 2022 and 2023 was placid, with little variation in its radio (or X-ray) emission, but in 2024 it showed five giant radio flares, brightening from a few mJy to > 10 Jy over a few days.

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Categories: Talks

Prospects for biological evolution on Hycean worlds

Planetary systems - Thu, 13/02/2025 - 10:32
arXiv:2502.07872v1 Announce Type: new Abstract: Recent detections of carbon-bearing molecules in the atmosphere of a candidate Hycean world, K2-18 b, with JWST are opening the prospects for characterising potential biospheres on temperate exoplanets. Hycean worlds are a recently theorised class of habitable exoplanets with ocean covered surfaces and hydrogen-rich atmospheres. Hycean planets are thought to be conducive for hosting microbial life under conditions similar to those in the Earth's oceans. In the present work we investigate the potential for biological evolution on Hycean worlds and their dependence on the thermodynamic conditions. We find that a large range of evolutionary rates and origination times are possible for unicellular life in oceanic environments for a relatively marginal range in environmental conditions. For example, a relatively small (10 K) increase in the average ocean temperature can lead to over twice the evolutionary rates, with key unicellular groups originating as early as $\sim$1.3 billion years from origin of life. On the contrary, similar decreases in temperatures can also significantly delay the origination times by several billion years. This delay in turn could affect their observable biomarkers such as dimethylsulfide, which is known to be produced predominantly by Eukaryotic marine phytoplankton in Earth's oceans. Therefore, Hycean worlds that are significantly cooler than Earth may be expected to host simpler microbial life than Earth's oceans and may show weaker biosignatures, unless they orbit significantly older stars than the Sun. Conversely, Hycean worlds with warmer surface temperatures than Earth are more likely to show stronger atmospheric biosignatures due to microbial life if present.

Prospects for biological evolution on Hycean worlds

Recent IoA Publications - Thu, 13/02/2025 - 10:32
arXiv:2502.07872v1 Announce Type: new Abstract: Recent detections of carbon-bearing molecules in the atmosphere of a candidate Hycean world, K2-18 b, with JWST are opening the prospects for characterising potential biospheres on temperate exoplanets. Hycean worlds are a recently theorised class of habitable exoplanets with ocean covered surfaces and hydrogen-rich atmospheres. Hycean planets are thought to be conducive for hosting microbial life under conditions similar to those in the Earth's oceans. In the present work we investigate the potential for biological evolution on Hycean worlds and their dependence on the thermodynamic conditions. We find that a large range of evolutionary rates and origination times are possible for unicellular life in oceanic environments for a relatively marginal range in environmental conditions. For example, a relatively small (10 K) increase in the average ocean temperature can lead to over twice the evolutionary rates, with key unicellular groups originating as early as $\sim$1.3 billion years from origin of life. On the contrary, similar decreases in temperatures can also significantly delay the origination times by several billion years. This delay in turn could affect their observable biomarkers such as dimethylsulfide, which is known to be produced predominantly by Eukaryotic marine phytoplankton in Earth's oceans. Therefore, Hycean worlds that are significantly cooler than Earth may be expected to host simpler microbial life than Earth's oceans and may show weaker biosignatures, unless they orbit significantly older stars than the Sun. Conversely, Hycean worlds with warmer surface temperatures than Earth are more likely to show stronger atmospheric biosignatures due to microbial life if present.

Searching for Hot Water World Candidates with CHEOPS: Refining the radii and analysing the internal structures and atmospheric lifetimes of TOI-238 b and TOI-1685 b

Recent IoA Publications - Thu, 13/02/2025 - 10:30
arXiv:2502.07887v1 Announce Type: new Abstract: Studying the composition of exoplanets is one of the most promising approaches to observationally constrain planet formation and evolution processes. However, this endeavour is complicated for small exoplanets by the fact that a wide range of compositions is compatible with their bulk properties. To overcome this issue, we identify triangular regions in the mass-radius space where part of this degeneracy is lifted for close-in planets, since low-mass H/He envelopes would not be stable due to high-energy stellar irradiation. Planets in these Hot Water World triangles need to contain at least some heavier volatiles and are therefore interesting targets for atmospheric follow-up observations. We perform a demographic study to show that only few well-characterised planets in these regions are currently known and introduce our CHEOPS GTO programme aimed at identifying more of these potential hot water worlds. Here, we present CHEOPS observations for the first two targets of our programme, TOI-238 b and TOI-1685 b. Combined with TESS photometry and published RVs, we use the precise radii and masses of both planets to study their location relative to the corresponding Hot Water World triangles, perform an interior structure analysis and study the lifetimes of H/He and water-dominated atmospheres under these conditions. We find that TOI-238 b lies, at the 1-sigma level, inside the corresponding triangle. While a pure H/He atmosphere would have evaporated after 0.4-1.3 Myr, it is likely that a water-dominated atmosphere would have survived until the current age of the system, which makes TOI-238 b a promising hot water world candidate. Conversely, TOI-1685 b lies below the mass-radius model for a pure silicate planet, meaning that even though a water-dominated atmosphere would be compatible both with our internal structure and evaporation analysis, we cannot rule out the planet to be a bare core.

Searching for Hot Water World Candidates with CHEOPS: Refining the radii and analysing the internal structures and atmospheric lifetimes of TOI-238 b and TOI-1685 b

Planetary systems - Thu, 13/02/2025 - 10:30
arXiv:2502.07887v1 Announce Type: new Abstract: Studying the composition of exoplanets is one of the most promising approaches to observationally constrain planet formation and evolution processes. However, this endeavour is complicated for small exoplanets by the fact that a wide range of compositions is compatible with their bulk properties. To overcome this issue, we identify triangular regions in the mass-radius space where part of this degeneracy is lifted for close-in planets, since low-mass H/He envelopes would not be stable due to high-energy stellar irradiation. Planets in these Hot Water World triangles need to contain at least some heavier volatiles and are therefore interesting targets for atmospheric follow-up observations. We perform a demographic study to show that only few well-characterised planets in these regions are currently known and introduce our CHEOPS GTO programme aimed at identifying more of these potential hot water worlds. Here, we present CHEOPS observations for the first two targets of our programme, TOI-238 b and TOI-1685 b. Combined with TESS photometry and published RVs, we use the precise radii and masses of both planets to study their location relative to the corresponding Hot Water World triangles, perform an interior structure analysis and study the lifetimes of H/He and water-dominated atmospheres under these conditions. We find that TOI-238 b lies, at the 1-sigma level, inside the corresponding triangle. While a pure H/He atmosphere would have evaporated after 0.4-1.3 Myr, it is likely that a water-dominated atmosphere would have survived until the current age of the system, which makes TOI-238 b a promising hot water world candidate. Conversely, TOI-1685 b lies below the mass-radius model for a pure silicate planet, meaning that even though a water-dominated atmosphere would be compatible both with our internal structure and evaporation analysis, we cannot rule out the planet to be a bare core.

Recovering the structure of debris disks non-parametrically from images

Planetary systems - Thu, 13/02/2025 - 10:28
arXiv:2502.08584v1 Announce Type: new Abstract: Debris disks common around Sun-like stars carry dynamical imprints in their structure that are key to understanding the formation and evolution history of planetary systems. In this paper, we extend an algorithm (rave) originally developed to model edge-on disks to be applicable to disks at all inclinations. The updated algorithm allows for non-parametric recovery of the underlying (i.e., deconvolved) radial profile and vertical height of optically thin, axisymmetric disks imaged in either thermal emission or scattered light. Application to simulated images demonstrates that the de-projection and deconvolution performance allows for accurate recovery of features comparable to or larger than the beam or PSF size, with realistic uncertainties that are independent of model assumptions. We apply our method to recover the radial profile and vertical height of a sample of 18 inclined debris disks observed with ALMA. Our recovered structures largely agree with those fitted with an alternative visibility-space de-projection and deconvolution method (frank). We find that for disks in the sample with a well-defined main belt, the belt radius, fractional width and fractional outer edge width all tend to increase with age, but do not correlate in a clear or monotonic way with dust mass or stellar temperature. In contrast, the scale height aspect ratio does not strongly correlate with age, but broadly increases with stellar temperature. These trends could reflect a combination of intrinsic collisional evolution in the disk and the interaction of perturbing planets with the disk's own gravity.

Recovering the structure of debris disks non-parametrically from images

Recent IoA Publications - Thu, 13/02/2025 - 10:28
arXiv:2502.08584v1 Announce Type: new Abstract: Debris disks common around Sun-like stars carry dynamical imprints in their structure that are key to understanding the formation and evolution history of planetary systems. In this paper, we extend an algorithm (rave) originally developed to model edge-on disks to be applicable to disks at all inclinations. The updated algorithm allows for non-parametric recovery of the underlying (i.e., deconvolved) radial profile and vertical height of optically thin, axisymmetric disks imaged in either thermal emission or scattered light. Application to simulated images demonstrates that the de-projection and deconvolution performance allows for accurate recovery of features comparable to or larger than the beam or PSF size, with realistic uncertainties that are independent of model assumptions. We apply our method to recover the radial profile and vertical height of a sample of 18 inclined debris disks observed with ALMA. Our recovered structures largely agree with those fitted with an alternative visibility-space de-projection and deconvolution method (frank). We find that for disks in the sample with a well-defined main belt, the belt radius, fractional width and fractional outer edge width all tend to increase with age, but do not correlate in a clear or monotonic way with dust mass or stellar temperature. In contrast, the scale height aspect ratio does not strongly correlate with age, but broadly increases with stellar temperature. These trends could reflect a combination of intrinsic collisional evolution in the disk and the interaction of perturbing planets with the disk's own gravity.