Het ontbrekende heelal

Auke Pieter Colijn, werkzaam aan de UvA en UU (bijzonder hoogleraar) is een experimenteel astrofysicus. Hij test of theorieën kloppen. Hij is een van de 40 onderzoekers van de detector in Gran Sasso (LNGS). Het heelal lijkt heel eeg leeg. De massa van sterren en planeten geeft maar een heel lage dichtheid.

Als je de snelheid van sterren in een sterrenstelsel (middels roodverschuiving) meet, verwacht je een afnemende curve. Sterren dichtbij de kern bewegen sneller dan verder weg bij het centrum. Na metingen blijkt dat niet zo te zijn:

Er lijkt massa te missen.

Het hele heelal is 2 graden Kelvin. Samenstelling heelal nu: donkere materie 72%, atomen 4,6%, donkere materie 23%. Donkere materie zendt geen licht uit. 13,7 miljard jaar geleden: donkere materie 63%, atomen 12%, fotonen 15%, neutrino’s 10%.

Donkere energie heb je nodig om te verklaren om te verklaren dat het heelal steeds sneller uitdijdt. Op een gegeven moment (miljarden jaren later) kun je alleen maar de sterren van de Melkweg ziet. Het licht van andere sterren bereikt ons niet meer.

Alles is opgebouwd uit 3 onderdelen: elektronen, up en down quarks.

Theorieën met mogelijke deeltjes die proberen om donkere materie te verklaren:


Het gewicht van donkere materie op aarde is slechts 300 gram. Donkere materie is niet gelijk verdeeld.
3 manieren om donkere materie te meten: indirect via satellieten, zelf maken via een deeltjesversneller en direct meten.


Detectoren richten zich op 1 van de 3 volgende gevolgen van de botsing tussen donkere materie en atomen: warmte, zendt het licht uit of komen er ionen uit (ionisatie). Alle detectoren zitten zo diep mogelijk. Om zo min mogelijk last te hebben van andere deeltjes. De faciliteiten in Gran Sasso (midden Italië):


Waarom moeilijk om te detecteren: nagenoeg is alles radioactief. Alle onderdelen zijn getest op radioactiviteit. Net begonnen met meten. Meest gevoelige detector op dit moment.

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Solar Eclipse 2017

Our trip to the Solar Eclipse on 21 August is planned. We plan to see the solar eclipse in Rexburg, Idaho. Totality will last 2 minutes and 17 seconds in Rexburg and Rexburg has a high chance of clear skies in summer. We’ll keep a close eye on the weather forecast and are able to drive to another place.

More info about the solar eclipse in Rexburg can be found at:

https://www.greatamericaneclipse.com/idaho/

http://www.eclipse2017.org/2017/communities/states/ID/Rexburg_90.htm

https://en.wikipedia.org/wiki/Solar_eclipse_of_August_21,_2017

 

Very Large Telescope (VLT)

Once upon a time …. the members of the European Southern Observatory (ESO) decided to build a Very Large Telescope in Chile. It’sthe start of a great story.

There are 4 telescopes (Antu, Kueyen, Melipal and Yepun) who work together imaging astronomic phenomenons 25 times better than with the individual telescopes. They’re huge. The mirrors have a diameter of 8.2 m!!! The telescopes are situated in Chile,  high in the mountains, with the clearest skies on our planet.

A lot of research is already done with the VLT. You may find more information on the ESO website, which contains a couple of very useful links (especially about the science with the telescopes). http://www.eso.org/public/teles-instr/vlt/

Tours are available under certain conditions: http://www.eso.org/public/about-eso/visitors/paranal/

Now I leave you with some of the most beautiful pictures of the VLT (credit ESO website)

eso-paranal-07

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Epic Social Media Gathering at the VLT and ALMA in Chile

ann16010aThe European Southern Observatory organizes a social gathering for 8 lucky people to witness the Mercury transit from Chile. The places were it is held is like a dream. In the middle of the desert with the clearest skies on this planet. A real bucket list place and event for astronomy fans.

Of course I applied. Would be a dream come true for this would be astronomer.

Time to tell something more about my dream of becoming an astronomer. My first presentation at primary school was about the solar system. I must have been 9 or 10 years old and already knew that I wanted to be an astronomer. The planets and stars were fascinating and so much to learn about them. And so much new discoveries in our lifetime. I held onto that dream until I was 18 and had to choose which university I would attend. I graduated high school with a beta orientation (math, physics, chemistry and biology). And then I started to doubt if I was good enough for this program. I was at that moment really unsure of my capabilities and skills (like any other teenagers) and ended up choosing safe. I studied business economics instead. After all this years I’m still sad that I made the wrong choice. But I try to compensate by studying astronomy in my free time.

Going to Chile would be the highlight of my astronomy dream. So pick me!!!

Here you can find more info of this social gathering and you can apply yourself.

http://www.eso.org/public/announcements/ann16010/

 

Einstein was right: gravitational waves detected

2.5 years ago I already wrote about gravitational waves and the role of the LIGO and the Virgo detectors. On the first day that the two LIGO detectors started a gravitational wave from the merger of two black holes was detected. That’s how it got its name btw: GW150914 (Gravitational Wave 14 September 2015). 

Both black holes weighed 30 times the mass of the sun. The distance to Earth was a mere 1.3 billion light-years. Enormous amounts of energy were released when they merged. This energy changed the fabric of space and time and caused ripples. 

The two LIGO detectors spotted the wave at the same time confirming it was a real discovery. Whole new research lines will appear. Such a triumph for science, the theory of relativity and astronomy.  

Here the figure from the paper: 

 

In the news

I only post things that are realy remarkable in my opinion or things I experienced or heard first hand.

At this moment I follow a Coursera course titled “Origins – Formation of the Universe, Solar System, Earth and Life”. Highly recommended. They use the findings in the univere to explain life on Earth and vice versa. What triggered life on Earth and may lead to life forms on other planets outside the Solar System.

The Rosetta mission of ESA has been in the news for weeks now. And fully justified of course.
The following first findings got my attention.

Organic molecules are found on the comet. This isn’t a great surprise because organic molecules have been found by comet Halley (Giotto in 1986) and by Comet Wild 2 (Stardust 2004). Organic molecules can be the building blocks of life. “Scientists still aren’t sure what kind of organics — carbon-containing molecules that are the building blocks of life on Earth — were found.” (see http://www.space.com/27814-philae-comet-lander-organic-molecules.html)

Exciting weeks for science!

The night sky from the ISS

vanuit iss

I wondered often how the night sky would look from the ISS. Most photos are taken from the Earth. The Earth is indeed a fantastic object, but so is the sky. This week I stumbled on a night sky photo from the ISS, taken on March 4th (by @PC0101). So stunning I had to share this one.