--- _The discovery of exoplanet TOI-2431 b adds to the growing list of extreme exoplanets. Artist impression of an exoplanet in orbit around an orange star. (Credit : NASA Ames/SETI Institute/JPL-Caltech)_ --- Astronomers have found a fascinating new world that challenges our understanding of planetary systems. Using NASA's Transiting Exoplanet Survey Satellite (TESS), an international team of researchers has discovered TOI-2431 b, an Earth sized planet orbiting a nearby star just 117 light years away. What makes this discovery extraordinary isn't just the planet's size, it’s how incredibly fast it races around its star. --- _Image of the Transiting Exoplanet Survey Satellite (Credit : NASA)_ TOI-2431 b completes a full orbit around its host star in just 5.4 hours, making it one of the shortest "years" ever recorded for any known planet. To put this in perspective, while Earth takes 365 days to orbit the Sun, this distant world experiences more than 1,600 "years" in the same timeframe. The planet sits extremely close to its star too, only about 0.0063 AU away, which is roughly 933,000 kilometres. This proximity comes with extreme consequences. The planet's surface temperature reaches approximately 2,000 Kelvin (about 1,727°C), hot enough to melt most rocks and metals. Scientists believe the planet's surface is likely molten, creating a landscape of liquid rock and metal. Despite being classified as Earth sized, TOI-2431 b is quite different from our home planet. With a radius about 1.53 times larger than Earth and a mass 6.2 times greater, this world is significantly denser than Earth. Its density of 9.4 grams per cubic centimetre suggests it's made of much heavier materials, possibly containing a large iron core or other dense metals. --- _Newly discovered exoplanet TOI-2431 b is described as an Earth-sized planet but is far from similar to our home world (Credit : NASA/Apollo 17 crew)_ The intense gravitational forces from its nearby star have likely changed the planet's shape. The team estimate that TOI-2431 b is tidally deformed, with its shortest axis being about 9 percent shorter than its longest axis, giving it a somewhat flattened appearance rather than a perfect sphere, like the Earth but somewhat more extreme. Perhaps most intriguingly, this planet won't be around forever. The researchers calculated that TOI-2431 b has a tidal decay timescale of about 31 million years, the shortest known among similar ultra short period planets. This means the planet is gradually spiralling into its star and will eventually be consumed, though the planet’s eventual demise won't happen for many millions of years. The discovery team, led by Kaya Han Taş of the University of Amsterdam, confirmed the planet using multiple observation methods, including TESS data, ground based telescopes, and specialised spectrographs. Scientists noted that TOI-2431 b would be an excellent target for the James Webb Space Telescope to study further, potentially revealing details about its surface composition and whether it retains any atmosphere despite the extreme conditions. This discovery adds to our growing catalog of extreme worlds and helps scientists understand how planetary systems form and evolve under different conditions, expanding our knowledge of the incredible diversity of planets in our Galaxy. Research Paper

Executive Summary: The Habitable Worlds Observatory (HWO) is the first astrophysics flagship mission with a key cross-divisional astrobiology science goal of searching for signs of life on rocky planets beyond our solar system. The Living Worlds Working Group under the Science, Technology, and Architecture Review Team (START) was charged with investigating how HWO could characterize potentially habitable exoplanets orbiting stars in the solar neighborhood, search for signs of life, and interpret potential biosignatures within a false positive and false negative framework. In particular, we focused on (1) identifying biosignatures that have spectral features in the UV-Vis-NIR wavelength range and defining their measurement requirements, (2) determining additional information needed from the planet and planet system to interpret biosignatures and assess the likelihood of false positives, and (3) assembling current knowledge of likely HWO target stars and identify which properties of host stars and systems are most critical to know in advance of HWO. The Living Worlds atmospheric biosignatures science case is considered one of the key drivers in the design of the observatory. An additional 10 astrobiology science cases were developed that collectively revealed key research gaps and needs required to fully explore the observatory parameter space and perform science return analyses. Investment in these research gaps will require coordination across the Science Mission Directorate and fall under the purview of the new Division-spanning astrobiology strategy.

Si hoy alguien quisiera construir algo parecido a un nuevo Hubble, lo lógico sería pensar en años de informes, revisiones y comités antes de que la primera...

Aside from Pandora, the launch also carried dozens of additional satellites, including two NASA-sponsored CubeSats.

New study suggests complex life unlikely around common stars, dashing hopes of extraterrestrial existence.

THE NEW SPACE RACE: SpaceX launches NASA’s Pandora exoplanet mission, 3 dozen other satellites (video).

Combining two kinds of quantum computing devices could be just the trick for taking better images of faint, faraway exoplanets

**Title:**First Detection of an Ultracool Dwarf at 340 MHz: VLITE Observations of EI Cancri AB **Author(s):** Michele L. Silverstein, Tracy E. Clarke, Wendy M. Peters, Emil Polisensky, Jackie Villadsen, Jordan M. Stone **First Author’s Institution:** Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA **Status:** Submitted to AAS Journals [open access] # What makes these dwarfs so cool? Ultracool dwarfs (UCDs) consist of the lowest mass stars and brown dwarfs, typically of spectral type M7 or “later” (lower effective temperature). They usually have masses of about 0.1 solar masses or less, about half or less of the Sun’s effective surface temperature, and are typically limited in size to a few-tenths of the Sun’s radius. These facts mean they appear very red, often peaking in the infrared, and their luminosities are typically only a few tenths of a percent of the Sun’s. Some are just massive enough to fuse Hydrogen, whereas the less massive brown dwarfs can sometimes fuse deuterium or don’t fuse at all, making them more analogous to planets. Studying these kinds of systems–which walk on the boundary of stars and planets–is critical to understanding the differences in their formation processes and evolution. _Figure 1: An annotated diagram of the Sun’s layers. The region between the internal radiative zone and the outer convective zone is called the tachocline. It is theorized to play an essential role in the production of the Sun’s strong magnetic field. Image Credit: NASA_ We’ve long known that magnetism plays an essential role in the Sun and the activity we observe. The Sun is a “differential rotator,” which results in a dynamo that can generate magnetic fields. Traditional solar dynamo theory invokes the tachocline–the region between a radiatively driven core and the outer convective layer–to produce the large magnetic field we observe from the Sun; see Figure 1. It is only present in stars with 0.3 solar masses and above since low-mass stars like UCDs don’t have sufficient core conditions to be radiative and are considered “fully” convective. However, radio observations and other methods, such as Zeeman-Doppler imaging, that have identified large-scale magnetic fields in UCDs challenge the tachocline’s role in magnetic field generation. In fact, the coolest known brown dwarf, 2MASS J1047+21, with a temperature of only 900 Kelvin, has a magnetic field of 1.7 kilo-Gauss, or 3000x that of Earth’s magnetic field. # The first radio star(s) at 340 MHz The observed emission frequency, its distribution, and other properties, such as polarization and temporal variability, can be used to infer the origin of a star’s radio emission. In today’s paper, the authors have chosen to search for radio emission in a frequency range in which no stars have been detected before. The P-band (~340 MHz) is a low frequency below the GHz regime, where the vast majority of radio studies have been conducted, including the first detection of radio emission from a UCD. Today’s paper focuses on a unique binary consisting of two nearly identical main-sequence M7 UCDs with 0.12 and 0.10 solar masses, designated EI Cancri A and B. The two stars are located in our solar backyard at 5.12 parsecs (16.7 light-years) and have a projected separation of approximately 13 AU (Earth-Sun distance units, 1 AU = 93 million miles = 150 million kilometers), so they are non-interacting. _Figure 2: (Left): The identification image of the VLITE detection at 340 MHz on 2018 April 26, created from seven hours of data on-source spanning a 28-hour dataset. The peak flux is 2.7+/-0.35 mJy/beam (SNR=7.71). (Right): A zoomed-in image, highlighting the location of the binary components EI Cancri A and B, alongside the marked positions of the three detections from 10-minute time-slices of the same dataset. Figure 1 from today’s paper._ The observations were conducted with the Very Large Array (VLA) using the VLA Low-band Ionosphere and Transient Experiment (VLITE) commensal system, which is present on 18 of the 27 antennas and observes simultaneously with all other VLA observations. Using this method, the authors detected EI Cancri. At an angular separation of 0.874 degrees from the primary target in the observation, they used a VLA observation of the famous blazar OJ 287 to create an image of EI Cancri and identified a source at its position. The low frequency also means lower resolution, so the source cannot unambiguously be attributed to EI Cancri A or B. After time-slicing the 7-hour dataset spanning 28 hours into 10-minute slices, the authors identified three independent bursts at 00:09, 02:48, and 03:41 on 2018 April 27. The image and the best-fitting positions of the three bursts are shown in Figure 2. The authors argue that if both systems are bursting, the image’s apparent central location is naturally explained. The inferred locations from the time-sliced images are consistent with the third burst originating from EI Cancri B. Regardless of the specific association, this represents the first confident radio detection of a UCD at 340 MHz since both stars in the system are UCDs. # The origin of radio emission in EI Cancri AB The authors consider incoherent processes (gyro-radiation) and coherent processes (plasma emission vs. electron cyclotron maser instability) as the origin of the emission. The best-known example is “gyro”/”gyromagnetic” emission, which arises from an electron spiraling along a magnetic field line under the influence of the electromagnetic force. This process can be referred to as cyclotron, gyro-synchrotron, or synchrotron emission, depending on the electron energy. Coherent processes like plasma emission and the electron cyclotron maser instability (ECMI) arise from unstable conditions in the plasma in the star’s atmosphere, and which one gets produced depends on the density and magnetic field strength. These processes are termed coherent because they involve electrons moving in concert, often resulting in highly polarized radio emission. A simple way to estimate which emission process is responsible is to calculate the brightness temperature; if it exceeds 1012 Kelvin, the process is more likely to be coherent than incoherent. The brightness temperature requires an estimate of the source size, which is unknown because there are no other detections at this frequency for comparison. The authors estimate the flaring region in the star’s atmosphere to be 1-5 stellar radii, which causes the resulting brightness temperature to fluctuate around the cutoff value, so a definitive determination isn’t possible yet. Other methods of identifying the emission process rely on frequency-dependent effects, polarization, and periodic signals at the star’s rotation period. Unfortunately, the low signal-to-noise ratio makes it challenging to investigate how the flare appears at different frequencies or polarizations. Since only three flares were detected over several hours and the shortest predicted rotation period of either star is 10 hours, searching for a periodic signal that might favor a coherent process is not yet possible without more data. # More observations and interpretations _Figure 3: Images from the VLA Sky Survey (VLASS) observing at 2-4 GHz (~10x the observing frequency of VLITE) of the EL Cancri system at its three observing epochs in 2019, 2021, and 2024. Both stars are confidently detected in all three epochs. Figure 2 from today’s paper._ In addition to the VLITE observations, the authors examined images available from the VLA Sky Survey (VLASS), an all-sky survey at higher frequencies. In the three observations spanning 2019, 2021, and 2024, both EI Cancri A and B were confidently detected; see Figure 3. The currently available VLASS images are limited to short, single-frequency, single-polarization snapshots and therefore also cannot probe the distinguishing properties of the emission mechanisms. The brightness temperature of the VLASS observations is similarly just on the cusp of the typical dividing value, so both gyro-synchrotron and a coherent process remain equally possible and consistent with the known GHz-emitting population of UCDs. Further observations using the VLA’s more sensitive dedicated P-band mode and higher frequencies over longer times, with accurate polarization measurements, could investigate the radio emission in greater detail and identify the emission process. Ultra-high-resolution radio observations using very-long-baseline interferometry could map stellar motion precisely and determine their orbital properties, and follow-up optical and infrared observations might solidify the true rotational periods. The radio detection of EI Cancri AB at 340 MHz offers a unique opportunity to study the system from multiple new perspectives. _Edited by Margaret Verrico_ ## Author * Will Golay I am a graduate student in the Department of Astronomy at Harvard University and the Center for Astrophysics | Harvard & Smithsonian, advised by Edo Berger. I study radio emission from transient astrophysical objects like tidal disruption events. View all posts

Exciting time as humanity nears answers to age-old questions. Is Earth the sole harbor of life? Discoveries on life beyond our planet on the horizon.

This artist's concept shows Kepler-385, a seven-planet system. Credit: NASA/Daniel Rutter **Why don’t planets fall into the stars they orbit if they’re constantly being pulled by gravity?****_ _** **_Lindsey Coughter_** _Rocky Mount, North Carolina_ This is a brilliant question because the notion of an orbit is counterintuitive. We know that massive objects (really, any objects with mass) gravitationally attract other massive objects; Newton’s law of universal gravitation is firmly established on this point. For instance, throw a baseball horizontally at about shoulder height and it will follow a curved path until it strikes the ground because Earth quickly draws the ball back to its surface. (Technically, Earth and the ball move toward each other and collide, but Earth is so much more massive than the ball that the former’s motion is practically zero.) A star and attendant planet, both being massive, should also come together rapidly. Instead, planets tend to maintain orbits around stars without actually crashing into them. To understand how planets are able to maintain a respectful distance from their parent stars, let’s return to the aforementioned baseball. Earlier, we imagined throwing it at normal human strength. Now, imagine you throw it again, but at a much higher velocity. The baseball still falls to the ground, but it takes longer — the parabolic path it follows is longer, due to its increased horizontal speed. Continue throwing the ball at ever-increasing velocities and the descending path the ball follows becomes increasingly longer. Finally, imagine that you are able to throw the ball so fast that the surface of Earth curves away from the ball’s path faster than the ball can fall. As a result, the ball’s curved path carries it _around_ Earth. The ball wouldn’t ever strike the ground but would constantly miss it altogether and continue falling — and end up orbiting the planet. Imagine throwing a ball horizontally at faster and faster speeds. Eventually, the ball will be traveling so fast that the surface of Earth will curve away from it faster than the ball will fall — so it will just keep falling and its path becomes an orbit. Credit: Astronomy: Theo Cobb The problem with this picture, apart from the fact that nobody can throw a ball that fast, is that atmospheric drag would quickly reduce the ball’s speed and cause it to strike the ground. Many artificial satellites moving around Earth, including the International Space Station, experience this atmospheric drag, albeit to a lesser extent due to the reduced particle density at such high altitudes. (As a result, these objects all eventually crash back to Earth unless they are boosted up again.) A planet, on the other hand, is essentially moving through a vacuum, and so no reduction of its velocity will occur. The planets are moving fast enough and at a great enough distance that as they “fall toward” the Sun, the Sun will never actually intersect with their orbital path. To paraphrase the late Douglas Adams, “The knack of flying is learning how to throw yourself at the ground and miss.” Orbits operate on essentially the same principle. _**Edward Herrick-Gleason** Astronomy Educator, St. John’s, Newfoundland and Labrador_