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Episode 112 – Brown Dwarfs, Dark Matter and Dark Energy

By Gurbir Dated: March 15, 2024 Leave a Comment

This episode was recorded in Tenerife with Professor Eduardo L Martín who is based at the Instituto de Astrofísica de Canarias. He is working on the European Space Agency’s mission, Euclid.

In time Euclid will shed light on both dark matter and dark energy. It was launched in July 2023 and arrived in its L2 orbit a month later. It has just two instruments which will produce a high-resolution 3-D map of a third of the sky, stretching back 10 billion years during its initial 6-year operational lifetime.

Professor Martín is not part of the Euclid Consortium the around 2500 scientists and engineers from more than a dozen countries who operate the Euclid Mission. He is one of the two Euclid mission Independent Legacy Scientists. Professor Martín is a specialist in substellar bodies, that is celestial bodies with a size about that of Jupiter but with around 50 times its mass. When initially theorised in the 1960s they were called Black Dwarfs but renamed in the 1970s by Jill Tarter as Brown Dwarfs.

Brown Dwarfs generate energy only through gravitational compression, not nuclear fusion. There is an overlap in surface temperature between young brown dwarfs and old very low-mass stars. Martín and his collaborators have developed spectroscopic methods to distinguish brown dwarfs from stars, in particular the Lithium test. More about this interesting role of Lithium in cosmology in Professor Martín’s book published in 2023 by the Institute of Physics, entitled “Lithium Across the Universe“. You can download several free-to-read chapters – here.

Brown Dwarfs emit mostly in the infrared not optical light as our sun. One of the two instruments on Euclid operates in the infrared and can detect these “dark ultracold objects of substellar mass“. Does Professor Martin think Euclid will find Brown Dwarfs? He told me in this recording, “that is what I put in the proposal so we had better do now”. He is supported by a postdoc Marusa Zerjal and a student Diego Martin, funded by the European Research Council.

The first images were released in November 2023. The spacecraft and its instruments are operating well and sending data. More about the Euclid mission, images released so far and a summary of the attributes of Normal Matter, Dark Matter and Dark Energy below.

Episode112 ESA’s Euclid Mission with Professor Eduardo Martin

Perhaps the most pressing question for astrophysicists is what is the cosmos made of. They have known for a long time that visible matter accounts only for the 5%, Dark Matter, 27% and Dark Energy 68%. Currently, most of the attributes of Dark Matter and Dark Energy remain a mystery. Helping to shed some answers to these questions is Euclid’s primary goal.

The visible matter is something we are surrounded by. It responds to all 4 known forces, electromagnetic, gravitation, and the strong and weak nuclear force. Dark matter is not dark, it’s invisible and is only detected through its gravitational influence on the matter we can see. Gravitational lensing is one manifestation.

Whereas gravity is a force of attraction, Dark Energy is repulsive, powering the expansion of the Universe. Its effects are observed by monitoring type 1a supernovae in distant galaxies. Some scientists consider Dark Energy as the Cosmological Constant that Einstein initially added and then removed from his General Theory of Relativity. The Cosmological Constant is now considered by some as the 5th fundamental force, after gravity, electromagnetism, and strong and weak nuclear forces.

  • Horse head Nebula. Credit ESA
  • Globular Cluster NGC6397. Credit ESA
  • Irregular Galaxy NGC6822. Credit ESA
  • Spiral galaxy IC342. Credit ESA Credit ESA
  • Perseus Cluster. Credit ESA

Summary of attributes for Normal Matter, Dark Matter and Dark Energy

AttributeNormal MatterDark MatterDark Energy
Formation TimeShortly after the Big BangLikely formed shortly after the Big BangBelieved to have originated with the expansion of the universe
LocationEverything we can see including Galaxies, stars, planets and the interstellar mediumPrimarily in galactic halos, halos around galactic clusters and permeates the universeHomogeneously distributed throughout space, associated with vacuum energy
Observational EvidenceEmission and absorption spectra, visible light, X-rays, cosmic microwave backgroundGravitational effects on visible matter, galaxy rotation curves; Dark matter inferred from galaxy cluster dynamics by Fritz Zwicky, 1933). Galaxy rotation curves suggest dark matter and the work of Vera Rubin from the 1970s.
Observation of gravitational lensing.
Acceleration of cosmic expansion, distant Type 1a supernova observations by Saul Perlmutter, Brian Schmidt, Adam Riess (1998-1999).
In time, it may turn out to be the 5th fundamental force.
Interaction with Electromagnetic ForceStrong interaction, contributes to various spectra and emissionsWeak or non-existent interactions with light and other EM wavesWeak or non-existent interactions with light and other EM waves
Interaction with Gravitational ForceExperiences gravitational attraction with other matterExperiences gravitational attraction, influencing cosmic structures. Exhibits a repulsive gravitational effect, driving cosmic expansion
Percentage Composition in the Universe~4.6% of the total mass-energy content~26.5% of the total mass-energy content~68.9% of the total mass-energy content
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Episode 100 Sandra Benitez Herrera – ESA Education Outreach

By Gurbir Dated: September 18, 2022 Leave a Comment

Astrophysicist Sandra Benitez-Herrera  talks about the opportunities for teachers and students made available by the European Space Agency‘s CESAR (Cooperation through Education in Science and Astronomy Research) program. This episode was recorded in Athens in July during Cospar 2022.

If you are a student or a teacher in Europe or beyond, Sandra explains how you make use of CESAR’s resources – optical, solar and radio telescopes, online seminars, face-to-face training and an enormous quantity of space data from ESA and other space agencies. All in one place and with no charge. She starts with an explanation of what CESAR is – in audio and Youtube video below.


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New Book – Atlas of Space Rocket Launch Sites

By Gurbir Dated: September 13, 2022 Leave a Comment

ISBN 978-3-86922-758-0
Size 240 x 300 mm
272 pages
500 images
Index
Glossary
Hardcover

** Description and look-inside below **

Available from: dom-publishers.com, www.amazon.com, www.freytagberndt.com, www.mondadoristore.it, www.lehmanns.de and www.abebooks.co.uk – a variety of suppliers at many lower prices.

Learn more from podcasts: New Space India, The Spaceshow and Aviation-Xtended

Book Reviews: www.wallpaper.com, www.raumfahrer.net, flugundzeit.blog, www.ivorypress.com and collectspace.com

To purchase signed copies directly from the authors contact Brian Harvey or Gurbir Singh


The book describes primary launch sites around the world including some that are historically significant but no longer operating (e.g Peenamunde) as well as the new kids on the block (e.g Kodiak).

The book is edited by Paul Meuser who has written the foreword and sourced most of the 500 or so majestic photos of launch sites and their environments. The majority of the text is authored by Dublin-based author Brian Harvey. A prodigious writer who has been writing on space programs of numerous countries since the 1970s. Katrin Soschinski designed stunning maps, the foundation of any atlas.

Copy of the back text page and a few sample pages from the book in the slide show below. These sample pages can be downloaded here albeit the quality is way inferior to the original.


Back page text

The machines that orbit our planet live in a void environment–
however, space travel itself does not exist in a vacuum. Traveling
to space is an immense effort of humans and machines, taking
not just ‘a small step for a man’ but leaving a huge carbon
footprint in the process. We are in the midst of a paradigm shift
in which private companies and leadership figures in the form of
Billionaires are re-popularizing space travel to an extent not seen
since the space race of the USSR and USA. Space exists isolated
from the place that births its mechanical and a few select human
inhabitants. Thus we tend to forget that every single thing that
exits our atmosphere takes with it more than just its own weight
of materials when it departs our fragile blue marble.

This book offers a unique look at the physical footprints of earth’s
launch sites. With most places hidden away in jungles, deserts, or
amidst the Central Asian steppes, these places exist for the most
part out of the eye of the general public. With satellites facilitating
our modern society and a modern space age ever-present in today’s
news cycle, it is now more important than ever to think about the
imprint these undertakings leave on earth. To begin to answer
the new socio-economic questions raised by our rapid expansion
into the void, we need to look no further than follow the cracks in
the concrete of our planetary launch sites. The rusty train tracks
leading to the pad break the pristine and sterile looks of space, and
reopen our eyes to the realities of space exploration.

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Episode 95 European Space Cooperation DeGaulle to ExoMars with Brian Harvey

By Gurbir Dated: September 24, 2021 Leave a Comment

The latest book from author Brian Harvey @BrianHarveyAut1, this is probably the first English language analysis of the individuals, institutions and early space projects that would eventually lead,  not just France, but Europe to its status as a leader in designing, building and operating complex space infrastructure. 

This is probably the first English language analysis of the individuals, institutions and early space projects that would eventually lead,  not just France,  but Europe to its status as a leader in designing, building and operating complex space infrastructure.

In the first chapter, “Early Days”, the author refers to John F. Kennedy’s little-known but perhaps most powerful speech on 10 June 1963, Strategy for Peace. Here it would have been interesting to see the author’s assessment on how collaboration in space has cultivated peace on Earth.

In this episode Brian talks about his motivation for writing this book and accessing the complex sources he needed to tell this story.

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A video of this interview is available on Youtube.

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