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New Facility Enables the Study of Shooting Stars in the Laboratory

Astronomy News - 29 August 2017 - 9:59am

Technology Development: In the last three years, a NASAsponsored team at the University of Colorado has developed a facility that allows “shooting stars” to be generated in laboratory conditions. The heart of this unique capability is a three-million-Volt electrostatic accelerator that is capable of accelerating small dust particles to velocities from 10- 70 km/s—roughly the range at which micrometeoroids enter Earth’s atmosphere and become “shooting stars.”

Back: The dust accelerator facility operated at the University of Colorado.
Front: The setup where the ablation of dust particles is studied. (Credit: IMPACT Institute)

 

While some micrometeoroids are visible to the naked eye, most are observable only by sensitive instruments such as radars. Researchers use this new facility to learn about the behavior of different types of accelerated dust particles so that scientists can better interpret measurements made in the field. In the laboratory, the accelerated particles are introduced into a chamber with elevated gas pressure, where they are heated rapidly through collisions with molecules. The heat causes some or all of the particle material to wear away—a process called ablation. Sensitive electronic and optical sensors in the chamber detect the amount of ionization generated and the light emitted along the path of the ablating particles, allowing researchers insight into the process.

Impact: This new facility provides information about how dust particles made of varying materials undergo an elementary process that occurs in unique conditions that are difficult to simulate. The experimental data generated by this facility are being used to improve the interpretation of meteor radar observations, with the goal of resolving the total mass input and the origin of the extraterrestrial material entering Earth’s atmosphere.

Status and Future Plans: In 2016, the research team extended the facility to include the capability to spatiallyresolve optical observations, which provides critical information about the particles’ deceleration during ablation. The team also successfully developed and tested new dust samples consisting of more complex mineral (or rocky) materials for acceleration in the facility. Currently, the research team is working on using these new samples to simulate differential ablation, where the more volatile elements evaporate first from the particle, followed by the more refractory elements. The differential ablation of meteoroids is responsible for the metallic layers observed in Earth’s upper atmosphere, and characterizing this process in the laboratory will enable better understanding of observed data.

Sponsoring Organization: SMD’s Heliophysics Division sponsors development of the ablation facility through the H-TIDeS program, with Prof. Zoltan Sternovsky as the PI. The dust accelerator is operated by the IMPACT Institute (Institute for Modeling Plasma, Atmospheres and Cosmic Dust), a member of NASA’s Solar System Exploration Research Virtual Institute (SSERVI), which is supported both by SMD and the Human Exploration and Operations Mission Directorate.

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Wonky signals from distant stars could be sign of exocomets

Astronomy News - 25 August 2017 - 8:55am

Astronomers looking at two stars 800 light years away say they may have found the first comets beyond our solar system

Distinguishing spin-aligned and isotropic black hole populations with gravitational waves

Astronomy News - 24 August 2017 - 9:23am
The direct detection of gravitational waves from merging binary black holes opens up a window into the environments in which binary black holes form. One signature of such environments is the angular distribution of the black hole spins. Binary systems that formed through dynamical interactions between already-compact objects are expected to have isotropic spin orientations (that is, the spins of the black holes are randomly oriented with respect to the orbit of the binary system), whereas those that formed from pairs of stars born together are more likely to have spins that are preferentially aligned with the orbit. The best-measured combination of spin parameters for each of the four likely binary black hole detections GW150914, LVT151012, GW151226 and GW170104 is the ‘effective’ spin. Here we report that, if the magnitudes of the black hole spins are allowed to extend to high values, the effective spins for these systems indicate a 0.015 odds ratio against an aligned angular distribution compared to an isotropic one. When considering the effect of ten additional detections, this odds ratio decreases to 2.9 × 10−7 against alignment. The existing preference for either an isotropic spin distribution or low spin magnitudes for the observed systems will be confirmed (or overturned) confidently in the near future.

Gravitational waves: History of black holes revealed by their spin

Astronomy News - 24 August 2017 - 9:23am
Four probable detections of gravitational waves have so far been reported, each associated with the merger of two black holes. Analysis of the signals allows formation theories of such black-hole systems to be tested. See Letter p.426

Supernova’s messy birth casts doubt on reliability of astronomical yardstick

Astronomy News - 24 August 2017 - 9:22am
Brightness of exploding stars may vary more than researchers realized.

‘Alien megastructure’ star may host Saturn-like exoplanet

Astronomy News - 24 August 2017 - 9:21am

Rather than being caused by extraterrestrial construction, the bizarre dimming of Tabby’s star could instead be due to a closely orbiting, ringed planet

Hinode Satellite Captures Powerful Aug. 21 Eclipse Images, Video

Astronomy News - 24 August 2017 - 9:18am
Portal origin URL: Hinode Satellite Captures Powerful Aug. 21 Eclipse Images, Video Portal origin nid: 408183Published: Wednesday, August 23, 2017 - 11:37Featured (stick to top of list): noPortal text teaser: As Americans across the nation watched the total solar eclipse Aug. 21, the international Hinode solar observation satellite, flying some 422 miles above the Pacific Ocean, caught its own unique angle on the natural phenomenon.Portal image: A second image from Hinode of the Aug. 21 total solar eclipse, taken approximately 5 minutes farther into lunar transit. Science Categories: Sun

Best Ever Image of a Star’s Surface and Atmosphere

Astronomy News - 24 August 2017 - 9:16am
Using ESO’s Very Large Telescope Interferometer astronomers have constructed the most detailed image ever of a star — the red supergiant star Antares. They have also made the first map of the velocities of material in the atmosphere of a star other than the Sun, revealing unexpected turbulence in Antares’s huge extended atmosphere. The results were published in the journal Nature.

When is the next solar eclipse near you?

Astronomy News - 24 August 2017 - 9:15am

Find out when you can next witness a solar eclipse in your country with our eclipse calculator.