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Despite lack of large marsquakes, InSight team fixes size of crust, mantle, and core.

Using the Parkes radio telescope, Chinese astronomers have investigated an isolated pulsar known as PSR J1047−6709 and detected dozens of giant pulses during the bright state of this source. The finding is reported in a paper published December 10 on the arXiv pre-print repository.

Pulsars are highly magnetized, rotating neutron stars emitting a beam of electromagnetic radiation. They are usually detected in the form of short bursts of radio emission, however, some of them are also observed using optical, X-ray and gamma-ray telescopes. To date, most pulsars have been discovered using the Parkes Observatory in Australia.

Some pulsars showcase the so-called giant pulses (GPs)—short-duration, burst-like radio emissions from a pulsar, with energies exceeding the average pulse energy by 10 times or even much more. So far, such activity has only been detected in 16 pulsars.

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The team, led by Cornell postdoctoral researcher Jake D. Turner, Philippe Zarka of the Observatoire de Paris—Paris Sciences et Lettres University and Jean-Mathias Griessmeier of the Université d’Orléans published their findings in the forthcoming research section of the journal Astronomy & Astrophysics, on Dec. 16.

“We present one of the first hints of detecting an exoplanet in the radio realm,” Turner said. “The signal is from the Tau Boötes system, which contains a binary star and an exoplanet. We make the case for an emission by the planet itself. From the strength and polarization of the radio signal and the planet’s magnetic field, it is compatible with theoretical predictions.”

Here’s a tip.

On the 21 December solstice, the planets will look like one brilliant star as Jupiter’s and Saturn’s 12-and 29-year orbits bring them together. The last great conjunction was in May 2000, but its position in the sky meant it was difficult to see. The great conjunction of 1623 (when Galileo Galilei was still alive) was also hard to spot because, the Perth Observatory explains, it appeared close enough to the sun that it would have been “lost in the sun’s glare”.

“You’d have to go all the way back to just before dawn on 4 March 1226 to see a closer alignment between these objects visible in the night sky,” according to Patrick Hartigan, an astronomer from Rice University in Texas.

Continue reading “How to watch the Jupiter and Saturn ‘great conjunction’ of 2020” »

Another celestial treat to look out for in the run-up to Christmas.

This week Jupiter and Saturn are low in the southwest during the chilly December dusk. When this month began, they were separated by 2.1 degrees.

But in the days that followed, they have been slowly approaching each other; getting closer by about 0.1 degrees each day on their way toward the long-awaited “great conjunction” next Monday evening (Dec. 21). Their inching closer to each other will be further enlivened by the passage on Wednesday and Thursday evenings (Dec. 16–17) of a foreground waxing crescent moon.

There was nothing technical or physical stopping us from having moved on from Apollo to a permanent Moonbase, the development of industries in space and the establishment of the first human communities on Mars.

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Continue reading “We Must Be Our Own Kennedy” »

The Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy, sunspots have presented a challenge to understanding—their quasi-periodic variation in number, first noted 175 years ago, has stimulated community-wide interest to this day. A large number of techniques are able to explain the temporal landmarks, (geometric) shape, and amplitude of sunspot “cycles,” however, forecasting these features accurately in advance remains elusive. Recent observationally-motivated studies have illustrated a relationship between the Sun’s 22-year (Hale) magnetic cycle and the production of the sunspot cycle landmarks and patterns, but not the amplitude of the sunspot cycle. Using (discrete) Hilbert transforms on more than 270 years of (monthly) sunspot numbers we robustly identify the so-called “termination” events that mark the end of the previous 11-yr sunspot cycle, the enhancement/acceleration of the present cycle, and the end of 22-yr magnetic activity cycles. Using these we extract a relationship between the temporal spacing of terminators and the magnitude of sunspot cycles. Given this relationship and our prediction of a terminator event in 2020, we deduce that sunspot Solar Cycle 25 could have a magnitude that rivals the top few since records began. This outcome would be in stark contrast to the community consensus estimate of sunspot Solar Cycle 25 magnitude.

So young and already so evolved: Thanks to observations obtained at the Large Binocular Telescope, an international team of researchers coordinated by Paolo Saracco of the Istituto Nazionale di Astrofisica (INAF, Italy) was able to reconstruct the wild evolutionary history of an extremely massive galaxy that existed 12 billion years ago, when the universe was only 1.8 billion years old, less than 13% of its present age. This galaxy, dubbed C1-23152, formed in only 500 million years, an incredibly short time to give rise to a mass of about 200 billion suns. To do so, it produced as many as 450 stars per year, more than one per day, a star formation rate almost 300 times higher than the current rate in the Milky Way. The information obtained from this study will be fundamental for galaxy formation models for objects it for which it is currently difficult to account.

The most massive galaxies in the universe reach masses several hundred billion times that of the sun, and although they are numerically just one-third of all galaxies, they contain more than 70% of the stars in the universe. For this reason, the speed at which these galaxies formed and the dynamics involved are among the most debated questions of modern astrophysics. The current model of galaxy formation—the so-called hierarchical model—predicts that smaller galaxies formed earlier, while more massive systems formed later, through subsequent mergers of the pre-existing smaller galaxies.

On the other hand, some of the properties of the most massive galaxies observed in the local universe, such as the age of their stellar populations, suggest instead that they formed at early epochs. Unfortunately, the variety of evolutionary phenomena that galaxies can undergo during their lives does not allow astronomers to define the way in which they formed, leaving large margins of uncertainty. However, an answer to these questions can come from the study of the properties of massive galaxies in the early universe, as close as possible to the time when they formed most of their mass.