astroclad

Astrophysicist, CNRS

Homepage: https://astrocladistics.wordpress.com

Other phylogenetic studies in astrophysics

2016 seems is a new milestone for astrocladistics: fifteen years after the beginning of this adventure, and ten years after the first papers were published, other phylogenetic analyses,¬† in which I am not involved, have been published. They use either Maximum Parsimony (cladistics) or Neighbour Joining: Cladistical Analysis of the Jovian Satellites, Holt, Brown & […]

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From the Realm of the Nebulae to the Society of Galaxies. Dialogues on a Century of Research

This is the title of a new fantastic book that is quite timely: From the Realm of the Nebulae to the Society of Galaxies Dialogues on a Century of Research D’Onofrio, M.; Rampazzo, R. & Zaggia, S. (Eds.) Astrophysics and Space Science Library, Vol 45 Springer International Publishing, 2016. http://www.springer.com/fr/book/9783319310046 In order to outline possible […]

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Multivariate Approaches to Classification in Extragalactic Astronomy

This the title of our paper that makes a review of the tentative to base a (unsupervised) classification of galaxies on learning machine techniques : Multivariate Approaches to Classification in Extragalactic Astronomy Didier Fraix-Burnet, Marc Thuillard, Asis Kumar Chattopadhyay Frontiers in Astronomy and Space Sciences, 2015, 2 (3) It is an Open Access publication (not […]

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Why?

Why multivariate analyses are not more widespread in astrophysics, especially in the extragalactic domain? I have not really the answer (I have some ideas though…), but let me show some plots that should help convince (astro)physicists. Firstly, do you remember this conference help in 1990? This shows that the debate about the morphological classification of […]

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Transforming the Hubble Tuning Fork into a Piano

A Tuning Fork is a device used to tune musical instruments. It vibrates at a single frequency, it is a pure sound of a single note. The Hubble Diagram not only looks like a Tuning Fork, but is also sounds like it: morphology is a single note, a single parameter, and it is based on […]

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Gamma Ray Bursts and Cladistics

Another kind of astronomical objects has been successfully analyzed with maximum parsimony: Gamma Ray Bursts! These are still mysterious objects, extremely violent, that emit a lot of gamma-rays during tenths of a second to several seconds. Gamma-rays are very energetic electromagnetic radiation, more so than X-rays, UV and of course visible light. Gamma-ray detectors on […]

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Astrocladistics and galaxies: a milestone

Astrocladistics has the power to renew our classification of galaxies. I have explained why this is necessary. But after more than 10 years of developments, where are we standing in this ambitious and long term goal? A first step has been made forward in our publication: A six-parameter space to describe galaxy diversification. Fraix-Burnet, D., […]

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When observations do not fit into tradition

I have mentioned several times that the Hubble classification is a traditional approach of classification that is not adapted to modern data. I have also noticed that in the astrophysical literature modern statistical tools of clustering are often used in the sole purpose of retrieving the Hubble sequence without using the eyes. Or course, this […]

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Progress Report

Today, I have finished the chapter called “Diversification” which is fundamental to Astrocladistics since it explains why such a phylogenetic tool can be applied to galaxies (and beyond). With already completed chapters “Classification” and “Cladistics”, I have given all the concepts necessary to understand what is behind Astrocladistics. The next step is to go into […]

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Evolutionary cost

Cladistics looks for the relationships between taxa in terms of an evolutionary cost. By minimizing this cost, it is expected to find an evolutionary scenario that closely matches the hierarchical diversification process¬† through transmission with modification. In other words, inheritance of innovations from common ancestors is the simplest way to explain diversity. To understand why […]

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