Tagged: Universiteit Leiden Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 10:45 am on March 16, 2019 Permalink | Reply
    Tags: "There may be 50 billion free-floating planets in our galaxy", , , , , , Universiteit Leiden   

    From Universiteit Leiden via EarthSky: “There may be 50 billion free-floating planets in our galaxy” 


    From Universiteit Leiden

    via

    1

    EarthSky

    March 10, 2019
    Paul Scott Anderson

    There are at least 200 billion stars in our galaxy, and perhaps even a greater number of planets. Now a new study suggests there could be an additional 50 billion rogue planets, not orbiting any stars.

    1
    Artist’s concept of rogue planet CFBDSIR J214947.2-040308.9. Image via ESO/L. Calçada/P. Delorme/Nick Risinger (skysurvey.org)/R. Saito/VVV Consortium.

    Based on findings from space- and ground-based telescopes in recent years, astronomers now estimate there are billions of exoplanets – planets orbiting distant stars – in our galaxy alone. But what about planets that don’t orbit stars? How many rogue, or free-floating planets wander the depths of space unbound? Some have already been found, and earlier this year astronomers at the University of Leiden in the Netherlands announced results of their new study, suggesting there are some 50 billion free-floating planets in our Milky Way galaxy.

    These astronomers’ results were published on February 14, 2019, in the peer-reviewed journal Astronomy and Astrophysics[not made available at A&A see “astronomers’ results”.pdf on prior link.]

    Only a dozen or so rogue planets have been discovered. How did these astronomers’ research determine there might be 50 billion more?

    They ran computer simulations of 1,500 stars in the Trapezium star cluster, a well-known region of star formation located some 1,300 light-years away in the Orion Nebula, in the direction of our constellation Orion.

    The simulation included 2,522 planets orbiting 500 stars within the Trapezium cluster and showed that 357 of them would become free-floating planets within the first 11 million years of their evolution. Simon Portegies Zwart, an astronomer at the University of Leiden, recently told Bruce Dorminey of Forbes:

    “Of these, 281 leave the cluster, others remain bound to the cluster as free-floating intra-cluster planets.”

    2
    View of the Orion Nebula – a well-known region of star formation – via the Hubble Space Telescope. The Trapezium star cluster is the bright area just left of center. It contains about 2,000 known stars, but there may be more as well. It is a young open cluster where the stars are all roughly the same age. Image via NASA/ESA/Hubble Space Telescope.

    NASA/ESA Hubble Telescope

    So 281 of 2,522 newly born planets would leave their original star-forming cluster altogether, to roam the space between stars and star clusters, according to this computer simulation. The researchers then extrapolated those numbers to the rest of the galaxy, based on estimates of 200 billion stars in our galaxy. After all, the Trapezium star cluster is just one of thousands of known star clusters. All of the Milky Way’s stars are thought to have originated in vast star-forming clouds like those in the Orion Nebula, and to have started life in star clusters much like the Trapezium star cluster.

    If, as calculated, about a quarter of the Milky Way’s stars have lost one or more planets, as many as 50 billion planets should be rogue or free-floating, in our galaxy alone!

    Bound exoplanets likely outnumber stars in the galaxy; our single sun has eight major planets, and we’ve now seen thousands of planets orbiting single stars in multiple-planet systems. The estimates for the total numbers of planets in our Milky Way – both bound to stars, and rogue – is staggering.

    Just a few decades ago, it wasn’t yet known if any exoplanets existed. Now, current observations suggest there are hundreds of billions. Combine that with the billions of galaxies, and the implications are mind-blowing.

    3
    Closer view of the Trapezium star cluster in the Orion Nebula (bright stars near center of photo). Image via ESO/M.McCaughrean et al. (AIP).

    Here is another question. Might any of those free-floating planets collide with other planets or with their stars? They can and do, according to these astronomers’ recent computer simulation. Zwart said in Forbes:

    “Collisions among planets and between planets and their host star are common. This happens in more than three percent of planetary systems.”

    Zwart also thinks that our own solar system might have lost one or two planets – probably less massive than Neptune – earlier in its youth. He said:

    “But who knows what happened very early on, when Jupiter and Saturn had just formed and the rocky planets just started to emerge.”

    4
    Artist’s concept of exoplanet Kepler-186f. Most exoplanets – as might be assumed – orbit their own stars, but there may be billions more in our galaxy alone that do not. NASA/JPL-Caltech/T. Pyle.

    The ejection of planets from their home planetary systems might be more common in denser star clusters (the Trapezium star cluster is considered a “looser” cluster), since more frequent encounters between stars in dense clusters will make the planetary systems unstable. But the study of the Trapezium cluster shows that planets leave their home systems in looser clusters as well.

    Two of the dozen or so confirmed rogue planets so far were announced last year – OGLE-2012-BLG-1323 and OGLE-2017-BLG-0560. The first is estimated to have a mass between Earth and Neptune, while the other has a mass between Jupiter and a brown dwarf star.

    Rogue planets are not easy to detect, but as astronomers learn more about them, they’ll be able to find more in the coming years. If this new study is any indication, there are many of them awaiting discovery.

    Bottom line: The existence of 200 billion stars in our galaxy – and an even greater number of planets – is difficult enough to wrap our minds around. The idea of another 50 billion planets just floating around, not bound to any stars, is even more incredible. It might sound like science fiction, but, if astronomers at the University of Leiden in the Netherlands are right, these 50 billion rogue planets do exist.

    See the full article here.

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Universiteit Leiden Heijmans onderhoudt

    Universiteit Leiden was founded in 1575 and is one of Europe’s leading international research universities. It has seven faculties in the arts, sciences and social sciences, spread over locations in Leiden and The Hague. The University has over 6,500 staff members and 26,900 students. The motto of the University is ‘Praesidium Libertatis’ – Bastion of Freedom.

     
  • richardmitnick 11:53 am on October 17, 2018 Permalink | Reply
    Tags: Closing in on a giant ringed planet, , Currently the existence of the exoplanet dubbed J1407b is only hypothetical, The mystery of an exoplanet with a ring system more than 100 times larger than the one that girdles Saturn will not be resolved until at least 2021 evidence suggests., The star J140747.93−394542.6, Universiteit Leiden   

    From Universiteit Leiden via COSMOS: “Closing in on a giant ringed planet” 

    From Universiteit Leiden

    via

    COSMOS

    17 October 2018
    Andrew Masterson

    Century-old photographs aid in the hunt for a massive and elusive system observed just once in more than a century.

    1
    An artist’s impression of the mystery exoplanet surrounded by a massive ring system. Credit Ron Miller

    The mystery of an exoplanet with a ring system more than 100 times larger than the one that girdles Saturn will not be resolved until at least 2021, evidence suggests.

    Currently, the existence of the exoplanet, dubbed J1407b, is only hypothetical – a speculative answer to the question of why in 2007 a star, J140747.93−394542.6, or J1407 for short, 460 light-years from Earth in the constellation of Centaurus, appeared to undergo “a series of symmetric, deep eclipsing events”.

    The ostensible eclipses – detected as a periodic dimming of the star’s light – occurred over a 52-day period. However, only one of them was observed in detail, limiting, thus, the amount of information that could be gleaned. A favoured, if tentative, explanation for the phenomenon was that light from J1407 was temporarily obscured (from the point of view of Earth observers) by an object surrounded by a vast array of rings.

    In 2012, American Association of Variable Star Observers (AAVSO) relayed a request from Eric Mamajek of the Cerro Tololo Interamerican Observatory in Chile for assistance in monitoring the star in the hope of seeing another fade-out.

    CTIO an astronomical observatory located on Cerro Tololo in the Coquimbo Region of northern Chile, with additional facilities located on Cerro Pachón about 10 kilometres (6.2 mi) to the southeast. Altitude 2,207 m (7,241 ft)

    The suggested “ringed companion”, wrote the AAVSO’s Elizabeth Waagen, was “likely to be a brown dwarf or giant planet” that “may constitute a moon-forming ‘protoexosatellite disk’.”

    Thus far, however, the world’s astronomers have come up with bupkis.

    Now Robin Mentel of Leiden University in the Netherlands has come up with at least partial evidence to explain why.

    In a paper published in the journal Astronomy and Astrophysics, he and colleagues detail a novel investigation that involved looking to the past in order to constrain possibilities in the future.

    Over a period of two years, Mentel studied historical photographic plates showing the star, comparing its brightness with that of other, known, nearby stars to see if any dimming – and thus a likely eclipse – could be seen.

    By the end of the investigation, 490 plates had been studied, the oldest dating to 1890.

    And the result? Once again, bupkis. In every shot, J1407 shone fine and bright, its intensity never wavering.

    This, however, Mentel and colleagues are quick to point out, does not mean that there wasn’t an eclipse in the 107 years between the earliest image being recorded and the 2007 dimming being observed – after all, the plate collection did not constitute a continuous, unbroken record – but it does make it possible to suggest how much time elapses between events.

    On that basis, Mentel suggests that the ringed planet – or ringed brown dwarf – will transit the star again in either 2021 and 2024.

    Providing, of course, that it exists at all. One thing, however, is sure: In three years, the hunt for the possible “protoexosatellite disk” will kick up a gear.

    See the full COSMOS article here.
    See the full Leiden article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    3

    Leiden University was founded in 1575 and is one of Europe’s leading international research universities. It has seven faculties in the arts, sciences and social sciences, spread over locations in Leiden and The Hague. The University has over 6,500 staff members and 26,900 students. The motto of the University is ‘Praesidium Libertatis’ – Bastion of Freedom.

     
  • richardmitnick 7:27 am on May 23, 2017 Permalink | Reply
    Tags: , Dirac fermions, , Force-carrying bosons, , , , , Universiteit Leiden,   

    From Universiteit Leiden via phys.org: “Weyl fermions exhibit paradoxical behavior” 

    1

    Universiteit Leiden

    phys.org

    May 23, 2017
    No writer credit found

    1
    Credit: Leiden Institute of Physics

    Theoretical physicists have found Weyl fermions to exhibit paradoxical behavior in contradiction to a 30-year-old fundamental theory of electromagnetism. The discovery has possible applications in spintronics. The study has been published in Physical Review Letters.

    Physicists divide the world of elementary particles into two groups. On one side are force-carrying bosons, and on the other there are so-called fermions. The latter group comes in three different flavors. Dirac fermions are the most famous, comprising all matter. Physicists recently discovered Majorana fermions, which might form the basis of future quantum computers. Lastly, Weyl fermions exhibit weird behavior in, for example, electromagnets, which has sparked the interest of Prof. Carlo Beenakker’s theoretical physics group.

    Electromagnets

    Conventional electromagnets work on the interplay between electrical currents and magnetic fields. Inside a dynamo, a rotating magnet generates electricity, and vice versa: Moving electrical charges in a wire wrapped around a metal bar will induce a magnetic field. Paradoxically, an electric current produced within the bar in the same direction would produce a magnetic field around it, in turn generating a current in the opposite direction, and the whole system would collapse.

    Oddly enough, Beenakker and his group have found cases where this does actually happen. Following an idea from collaborator Prof. İnanç Adagideli (Sabanci University), Ph.D. student Thomas O’Brien built a computer simulation showing that materials harboring Weyl fermions actually exhibit this weird behavior. This has been observed before, but only at artificially short timescales, when the system didn’t get time to correct for the anomaly. The Leiden/Sabanci collaboration showed that in special circumstances—at temperatures close to absolute zero when materials become superconducting—the strange scenario occurs indefinitely.

    Until now, physicists considered this to be impossible due to underlying symmetries in the models used. That gives the discovery fundamental significance. “We study Weyl fermions mainly out of a fundamental interest,” says O’Brien. “Still, this research gives more freedom in the use of magnetism and materials. Perhaps the additional flexibility in a Weyl semimetal will be of use in future electronics design.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    3

    Leiden University was founded in 1575 and is one of Europe’s leading international research universities. It has seven faculties in the arts, sciences and social sciences, spread over locations in Leiden and The Hague. The University has over 6,500 staff members and 26,900 students. The motto of the University is ‘Praesidium Libertatis’ – Bastion of Freedom.

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
%d bloggers like this: