Tag Archives: Galaxies

Dissecting galaxies of the Local Universe with the CALIFA survey

Posted on October 1, 2014 | 1 comment

DP ENGLISH: This story belongs to the series “Double Post” which indicates posts that have been written both in English in The Lined Wolf and in Spanish in El Lobo Rayado.

DP ESPAÑOL: Esta historia entra en la categoría “Doble Post” donde indico artículos que han sido escritos tanto en español en El Lobo Rayado como en inglés en The Lined Wolf.

The Calar Alto Legacy Integral Field spectroscopy Area (CALIFA) survey is a project that aims to obtain data of around 600 nearby galaxies using the PMAS (Potsdam Multi Aperture Spectrophotometer) instrument of the 3.5m Telescope at the Calar Alto Observatory (Almería, Spain). The CALIFA survey combines the advantages of two observational techniques: imaging (that provides detailed information on galactic structure) and spectroscopy (that reveals the physical properties of galaxies, such as their kinematics, mass, chemical composition or age). The CALIFA survey makes use of the Integral Field Spectroscopy (IFS) technique, that allows obtaining at the same time around a thousand of spectra per galaxy, hence getting simultaneously imaging and spectra of astronomical objects.

A galaxy is “dissected” in thousands small regions, each one having its particular spectrum (wavelength) when using Integral Field Spectroscopy (IFS) techniques. The result is getting a datacube: two axes (x and y) possess the spatial information (the image of the galaxy, which can also be separated in several colours) and the third axis (wavelength) keep the spectroscopic information. Credit: Marc White (RSAA-ANU).

The CALIFA Project allows not only to inspect the galaxies in detail, but it also provides with data on the evolution of each particular galaxy with time: how much gas and when was it converted into stars along each phase of the galaxy’s life, and how did each region of the galaxies evolve along the more than ten thousand million years of cosmic evolution

Thanks to these data, astronomers of the CALIFA team have been able to deduce the history of the mass, luminosity and chemical evolution of the CALIFA sample of galaxies, and thus they have found that more massive galaxies grow faster than less massive ones, and that they form their central regions before the external ones (inside-out mass assembly). CALIFA has also shed light on how chemical elements needed for file are produced within the galaxies or on the physical processes involved on galactic collisions, and it has even observed the last generation of stars still in their birth cocoon.

CALIFA “panoramic view” (also CALIFA’s “Mandala”) representation, consisting of the basic physical properties (all of them derived from the CALIFA datacubes) of a subsample of 169 galaxies extracted randomly from the 2nd Data Release. It shows 1) broad band images (top center), 2) stellar mass surface densities (upper right), 3) ages (lower right), 4) narrow band images (bottom center; emission lines: Hα [N II] 6584 Å, and [O III] 5007 Å), 5) Hα emission (lower left) and 6) Hα kinematics (upper left). The CALIFA logo is placed at the central hexagon. Credit: R. García-Benito, F. Rosales-Ortega, E. Pérez, C.J. Walcher, S. F. Sánchez & the CALIFA team.

Today, Oct 1st, the CALIFA Team (and I’m part of it) has released 400 IFS datacubes for 200 nearby galaxies, the 2nd Data Release (DR2). The data are publically available and can now be used by astronomers around the world. The second CALIFA Data Release provides the fully reduced and quality control tested datacubes of 200 objects in two different spectral configurations. Each datacube contains ~1000 independent spectra, thus in total the CALIFA DR2 comprises ~400,000 independent spectra (~1.5 millon after cube reconstruction). The scientific details of the data included in the CALIFA DR2 are described in this scientific paper lead by the Spanish astronomer Rubén García-Benito.

More information about the CALIFA survey and its DR2:

– Calar Alto Observatory Press Release: http://www.caha.es/an-unprecedented-view-of-two-hundred-galaxies-of-the-local-universe.html

– Scientific paper about CALIFA DR2: García-Benito et al. (2014): http://arxiv.org/abs/1409.8302

– CALIFA webpage: http://www.caha.es/CALIFA/public_html

– CALIFA DR2 webpage: http://califa.caha.es/DR2

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Posted in Astrophysics, Galaxies, My Research, Observation, Observatories, Optical, Profesional

Tagged 2014, astronomy, CAHA, CALIFA, Galaxies, IFS

Colossal star formation in a dwarf galaxy

Posted on July 9, 2013 | Leave a comment

Text and photo published in a Calar Alto Photo Release, February 2008.

NGC 2366 is a dwarf galaxy placed at a distance of 11 millions of light-years (3.4 millions of parsecs). Its irregular shape and stellar content make it similar to the Magellanic Clouds, the two irregular dwarf galaxies very close to our own. For scale, NGC 2366 is about 20 000 light-years wide, what makes it twice as large as the Large Magellanic Cloud, and four times larger than the Small Magellanic Cloud, but still classified as a dwarf galaxy.

Astronomers deduced that NGC 2366 underwent a massive starburst episode only 50 million years ago and find that intense star formation is still taking place at several areas of this galaxy. This image beautifully displays the regions where young stars are being formed (red nebulae) because the surrounding hydrogen gas (the raw material from which stars form) has already been ionised by ultraviolet radiation from young stars. This ionised hydrogen is seen also as large filaments and shell structures shining in red throughout the this galaxy. The most outstanding star forming regions are seen towards the upper-right side of the image. The telltale youth of the stars that constitute this galaxy can be seen in the bluish colours of its elongated main body.

Dwarf galaxy NGC 2366 with the 3.5m CAHA telescope. Images in B (blue), R (green) y Hα (red). Credit: Janine van Eymeren & Ángel R. López-Sánchez.

The researchers performed these observations with the aim of tracing the ionised gas structures shining in the red light that astronomers call “H-alpha” (Hα). To do this they obtained deep (one hour integration) H-alpha images of this galaxy. The energy needed to make all this gas shine in red light is related to the energy coming from the young massive blue stars just formed, and astronomers can even deduce if these young stars are, or are not, the only energy source powering the reddish nebulae. The starburst mode of forming stars, astronomers believe, is an important one throughout the Universe but there is much to understand on why a galaxy chooses to suddenly transform its gas into stars at a colossal rate and with magnificent fireworks.

The image was obtained by Janine van Eymeren (AIRUB, ATNF) and Ángel R. López-Sánchez (CSIRO/ATNF) with the MOSCA camera attached to the 3.5 m telescope of Calar Alto Observatory. It was composed from individual frames taken in the B, Rand H-alpha bands. North is left, and East is down. The width of the image spans one third of the apparent size of the full Moon (approx. 10 arcminutes).

Link to the CAHA Photo Release: here
Link to the high-resolution image in my Flickr here.

Feeding, Feedback and Fireworks in galaxies

Posted on June 28, 2013 | 1 comment

During this week (23 – 28 June 2013), I’m participating in the international astrophysics conference “Feeding, Feedback, and Fireworks: Celebrating Our Cosmic Landscape”, which is hosted in the tropical paradise of Hamilton Island, one of the most important islands of the Whitsundays (Queensland, Australia). The conference is jointly supported by the Australian Astronomical Observatory (AAO) and the CSIRO Astronomy and Space Science (CASS) and it is the 6th of the Southern Cross Conference Series.

Poster of the “Feeding, Feedback, and Fireworks: Celebrating Our Cosmic Landscape”, jointly supported by the Australian Astronomical Observatory (AAO) and the CSIRO Astronomy and Space Science (CASS), being the 6th of the Southern Cross Conference Series. The Heart Reef near Hamilton Island appears in the foreground, while the Hubble Ultra-Deep Field image is the background image.
Credit: Heart Reef Photo and Fireworks: Ángel R. López-Sánchez (Australian Astronomical Observatory / Macquarie University); Hubble Ultra-Deep Field: NASA, ESA and R. Thompson (Univ. Arizona).

It has been a very intense and fruitful conference, with almost 100 participants (the majority coming from Australia, but many others from America, Europe, Asia and Africa), and we are discussing hot topics about how the diffuse gas is moved inside the galaxies (Feeding), how stars form in galaxies (Fireworks) and how these newborn stars alter the properties of their host galaxies and their surroundings (Feedback). We are also investigating the role of the Active Galactic Nuclei (AGN) in galaxy evolution: how are they triggered (Feeding) and how they affect their host galaxies and even the galaxy cluster their host galaxies reside (Feedback). All in the context of the cosmological evolution of the Universe, constraining theoretical models using observations, and trying to put all the pieces together to understand the evolution of the galaxies.

In my case I presented part of my multi-wavelength work in Blue Compact Dwarf Galaxies, which are small galaxies (smaller than 1/100 times the size and mass of the Milky Way) which are experiencing a very intense star-formation event. Hence, it seems all the dwarf galaxy is a giant nebula! I’ll describe these interesting objects in a future post.

I’m part of the “LOC”, the Local Organizing Committee, which is chaired by Amanda Bauer (AAO), aka @astropixie, and hence in the last months I have actively participate to get the conference smoothly running (conference booklet, schedule of the talks, helping in registration and photos). One of my tasks during this week was to get the “Conference Photo” which, as Amanda suggested, includes not only the beach and palm trees of the beautiful beach at Hamilton Island but also a nice night-sky photo showing the Southern Cross. The result is this:

Conference Photo of the “Feeding, Feedback, and Fireworks: Celebrating Our Cosmic Landscape” conference.
Photo Credit and composition: Ángel R. López-Sánchez (Australian Astronomical Observatory / Macquarie University).

The talks and more information about this exciting conference will be posted in the conference webpage soon.

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Posted in Astrophotography, Conferences, Galaxies, My Research

Tagged 2013, astronomy, Australia, Conference, Feedback, Feeding, Fireworks, Galaxies, Hamilton Island