Space

Betelgeuse, one of the most famous stars in the night sky, has a close companion, and that may explain why it dimmed dramatically in 2019-20.

About 640 light-years from the solar system, red supergiant star Betelgeuse in the constellation Orion is famous not only for its unmistakable color, but also because it’s one of the closest stars that could soon explode as a supernova.

Approximately 700 times larger than the sun, Betelgeuse has puzzled astronomers for years because it waxes and wanes in brightness every six years, with its recent “Great Dimming” event ultimately attributed to a dust cloud ejected by the star.

Scientists suspected it may have been caused by a companion star, but failed to detect it using NASA’s Hubble Space Telescope or the Chandra X-ray Observatory. Now it’s been found, after a team of astrophysicists led by Steve Howell, a senior research scientist at NASA Ames Research Center, has pointed the Gemini North Telescope in Hawaii at Betelgeuse. The team’s findings were published today in The Astrophysical Journal Letters.

notes : There seem to be two journals published, one of which is still accessible. url link to journal has been fixed

Paper - summarizes the key findings

• Rubin images clearly show the interstellar object 3I/ATLAS with a dust coma, indicative of activity. These observations provide the earliest high resolution evidence of detected cometary activity.

• Rubin multi-filter photometry is consistent with previous bservations in the literature, with significantly smaller error bars. There are not sufficient same-night multi-filter observations to examine surface/coma color or color evolution, but sufficient to exclude photometric variability on short timescales.

• The coma’s radius appeared to increase slightly over the 11 days from ∼ 6,520 km (UT 2025 June 21) to ∼9,380 km (UT 2025 July 02) as measured from azimuthally averaged radial profiles. We estimate an increase in coma level of ∆η ∼0.5 between 2025 June 21 June and 2025 July 2, which we assume to be a lower limit for several reasons, including that 3I/ATLAS was observed nearly head-on (very low phase angle) and the tail could have extended far along the z-axis, as projected on the sky.

• We obtain a V-band absolute magnitude of HV = (13.7 ± 0.2) mag and equivalent effective radius of ∼ (5.6 ± 0.7) km for the nucleus, assuming a spherically symmetric steady-state coma. Due to this simplifying assumption, we consider the latter result to be an upper limit to the true nucleus size. We estimate a mass loss rate ranging from 10 to 100 kg/s, depending on the grain sizes assumed to dominate, and we compute Afρ = (315 ± 15) cm for data obtained on UT 2025 July 2.

• We detect no short-term photometric variability. A sequence of measurements taken on UT 2025 July 2 constrains the apparent brightness variations of 3I/ATLAS to less than 0.1 mag on timescales of less than an hour.

• If the Rubin SSP pipelines had been processing the commissioning data in real time, our modeling shows that there were sufficient SV observations to identify 3I/ATLAS as a moving object.

• If the nominal SV survey strategy continues as planned, 3I/ATLAS should be observed in ten or more observations in each filter through mid August 2025. Future SV observations will likely be able to monitor the coma color as 3I/ATLAS moves towards perihelion.

• Analysis of the derived astrometry suggest that for bright high-SNR and extended active small bodies, the combination of Rubin’s large aperture and LSSTCam’s pixel scale are less impacted by asymmetrical coma provided precise positions for deriving accurate orbital parameters.

Crazy big orbits on those little guys

• Larger planets may be “water worlds” more capable of harboring life.
• Study raises questions about how common Earth-sized planets are in the universe.
• Researchers re-examine NASA satellite data to identify exoplanets.

Because the planet’s orbit is just seven days long, the gravitational forces from this orbital path tug at the star until plasma erupts from the surface...Heat causes the air to swell, increasing the cross‑section that stellar ultraviolet rays can hit, and leading to a vicious cycle that accelerates mass loss.

If the current pace holds, HIP 67522 b could shed enough hydrogen and helium to shrink into a mini‑Neptune within 100 million years.

It may even become a bare, rocky core after that. Such transformations explain why many mature planetary systems harbor small sub‑Neptunes while very close giant planets are rarer.

Similar run‑away erosion may have sculpted planets like CoRoT‑7 b, where today only a scorched super‑Earth remains...

Listen to the ESA/JAXA BepiColombo spacecraft as it flew past Mercury on 8 January 2025. This sixth and final flyby used the little planet's gravity to steer the spacecraft on course for entering orbit around Mercury in 2026.

What you can hear in the sonification soundtrack of this video are real spacecraft vibrations measured by the Italian Spring Accelerometer (ISA) instrument. The accelerometer data have been shifted in frequency to make them audible to human ears – one hour of measurements have been sped up to one minute of sound.

BepiColombo is always shaking ever so slightly: fuel is slightly sloshing, the solar panels are vibrating at their natural frequency, heat pipes are pushing vapour through small tubes, and so forth. This creates the eerie underlying hum throughout the video.

But as BepiColombo gets closer to Mercury, ISA detects other forces acting on the spacecraft. Most scientifically interesting are the audible shocks that sound like short, soft bongs. These are caused by the spacecraft responding to entering and exiting Mercury's shadow, where the Sun's intense radiation is suddenly blocked. One of ISA's scientific goals is to monitor the changes in the ‘solar radiation pressure’ – a force caused by sunlight striking BepiColombo as it orbits the Sun and, eventually, Mercury.

The loudest noises – an ominous ‘rumbling’ – are caused by the spacecraft's large solar panels rotating. The first rotation occurs in shadow at 00:17 in the video, while the second adjustment at 00:51 was also captured by one of the spacecraft’s monitoring cameras.

Faint sounds like wind being picked up in a phone call, which grow more audible around 30 seconds into the video, are caused by Mercury's gravitational field pulling the nearest and furthest parts of the spacecraft by different amounts. As the planet's gravity stretches the spacecraft ever so slightly, the spacecraft responds structurally. At the same time, the onboard reaction wheels change their speed to maintain the spacecraft's orientation, which you can hear as a frequency shift in the background.

This is the last time that many of these effects can be measured with BepiColombo's largest solar panels, which make the spacecraft more susceptible to vibrations. The spacecraft module carrying these panels will not enter orbit around Mercury with the mission's two orbiter spacecraft.

The video shows an accurate simulation of the spacecraft and its route past Mercury during the flyby, made with the SPICE-enhanced Cosmographia spacecraft visualisation tool. The inset that appears 38 seconds into the video shows real photographs taken by one of BepiColombo's monitoring cameras.

The Curiosity rover was sent up the Mount Sharp, the biggest sediments stack on Mars. On the way, it collected samples that indicated a portion of carbon dioxide in the Martian atmosphere might have been sequestered in the sedimentary rocks, just as it happens with limestone on Earth. This would have drawn carbon dioxide out of the atmosphere, reducing the greenhouse effect that warmed the planet.

Based on these findings, a team of scientists led by Benjamin Tutolo, a researcher at the University of Calgary, used this data to conclude Mars had a carbon cycle that could explain the presence of liquid water on its surface. Building on that earlier work, a team led by Edwin Kite, a professor of planetary science at the University of Chicago (and member of the Curiosity science team) has now built the first Martian climate model that took these new results into account. The model also included Martian topography, the luminosity of the Sun, latest orbital data, and many other factors to predict how the Martian conditions and landscape evolved over the span of 3.5 billion years.

Their results mean that any Martian life would have had a rough time of it.

The burgeoning space industry and the technologies society increasingly relies on – electric grids, aviation and telecommunications – are all vulnerable to the same threat: space weather.

Space weather encompasses any variations in the space environment between the Sun and Earth. One common type of space weather event is called an interplanetary coronal mass ejection.

These ejections are bundles of magnetic fields and particles that originate from the Sun. They can travel at speeds up to 1,242 miles per second (2,000 kilometers per second) and may cause geomagnetic storms.

They create beautiful aurora displays – like the northern lights you can sometimes see in the skies – but can also disrupt satellite operations, shut down the electric grid and expose astronauts aboard future crewed missions to the Moon and Mars to lethal doses of radiation.

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