Trying to confirm the proto brown dwarfs … I already have the answer. At least part of it. Weather is not kind to us, at least tonight.

Mean while, several nice pictures, taken with my mobile.

Several telescopes at the rim of the caldera

The WHT at sunset

SPITZER TELESCOPE OBSERVES BABY BROWN DWARF

PASADENA, Calif. — NASA’s Spitzer Space Telescope has contributed to the discovery of the youngest brown dwarf ever observed — a finding that, if confirmed, may solve an astronomical mystery about how these cosmic misfits are formed.

Brown dwarfs are misfits because they fall somewhere between planets and stars in terms of their temperature and mass. They are cooler and more lightweight than stars and more massive (and normally warmer) than planets. This has generated a debate among astronomers: Do brown dwarfs form like planets or like stars?

This image shows two young brown dwarf candidatess, objects that fall somewhere between planets and stars in terms of their temperature and mass. Brown dwarfs are cooler and less massive than stars, never igniting the nuclear fires that power their larger cousins, yet they are more massive (and normally warmer) than planets. When brown dwarfs are born, they heat the nearby gas and dust. Image with additional information at: http://spitzer.caltech.edu/images/2838-ssc2009-21a-Twin-Brown-Dwarfs-Wrapped-in-a-Blanket

Brown dwarfs are born of the same dense, dusty clouds that spawn stars and planets. But while they may share the same galactic nursery, brown dwarfs are often called “failed” stars because they lack the mass of their hotter, brighter siblings. Without that mass, the gas at their core does not get hot enough to trigger the nuclear fusion that burns hydrogen — the main component of these molecular clouds — into helium. Unable to ignite as stars, brown dwarfs end up as cooler, less luminous objects that are more difficult to detect — a challenge that was overcome in this case by Spitzer’s heat-sensitive infrared vision.

To complicate matters, young brown dwarfs evolve rapidly, making it difficult to catch them when they are first born. The first brown dwarf was discovered in 1995 and, while hundreds have been discovered since, astronomers had not been able to unambiguously find them in their earliest stages of formation until now. In this study, an international team of astronomers found a so-called “proto brown dwarf” while it was still hidden in its natal star-forming region. Guided by Spitzer data collected in 2005, they focused their search in the dark cloud Barnard 213, a region of the Taurus-Auriga complex well known to astronomers as a hunting ground for young objects.

“We decided to go several steps back in the process when (brown dwarfs) are really hidden,” said David Barrado of the Centro de Astrobiología in Madrid, Spain, lead author of the paper on the discovery in the Astronomy & Astrophysics journal. “During this step they would have an (opaque) envelope, a cocoon, and they would be easier to identify due to their strong infrared excesses. We have used this property to identify them. This is where Spitzer plays an important role because Spitzer can have a look inside these clouds. Without it this wouldn’t have been possible.”

Spitzer’s longer-wavelength infrared camera penetrated the dusty natal cloud to observe a baby brown dwarf named SSTB213 J041757. The data, confirmed with near-infrared imaging from Calar Alto observatory, revealed not one but two of what would potentially prove to be the faintest and coolest brown dwarfs ever observed.

Barrado and his team embarked on an international quest for more information about the two objects. Their overarching scientific objective was to observe and characterize the presence of this dusty envelope – proof of the celestial womb of sorts that would indicate that these brown dwarfs were, in fact, in their earliest evolutionary stages.

The twins were observed from around the globe, and their properties were measured and analyzed using a host of powerful astronomical tools. One of the astronomers’ stops was the Caltech Submillimeter Observatory in Hawaii, which captured the presence of the envelope around the young objects. That information, coupled with what they had from Spitzer, enabled the astronomers to build a spectral energy distribution – a diagram that shows the amount of energy that is emitted by the objects in each wavelength.

From Hawaii, the astronomers made additional stops at observatories in Spain (Calar Alto Observatory), Chile (Very Large Telescopes) and in New Mexico (Very Large Array). They also pulled decade-old data from the Canadian Astronomy Data Centre archives that allowed them to comparatively measure how the two objects were moving in the sky. After more than a year of observations, they drew their conclusions.

“We were able to estimate that these two objects are the faintest and coolest discovered so far,” Barrado said. Barrado said the findings potentially solve the mystery about whether brown dwarfs form more like stars or planets. The answer? They form like low-mass stars. This theory is bolstered, because the change in brightness of the objects at various wavelengths matches that of other very young, low-mass stars.

While further study will confirm whether these two celestial objects are in fact proto brown dwarfs, they are the best candidates so far, Barrado said. He said the journey to their discovery, while difficult, was “fun. “It is a story that has been unfolding piece by piece. Sometimes nature takes its time it give up its secrets.”

The paper’s other authors are M. Morales-Calderon, Centro de Astrobiología and Spitzer Science Center; A. Palau and A. Bayo, Centro de Astrobiología; I. de Gregorio-Monsalvo, European Southern Observatory; C. Eiroa, Universidad Autónoma de Madrid; N. Huelamo, Centro de Astrobiología; H. Bouy, Instituto de Astrofísica de Canarias and European Space Agency; O. Morata, Institute of Astronomy and Astrophysics and National Taiwan Normal University; and L. Schmidtobreick, European Southern Observatory. More information on the Spitzer Space Telescope is online at http://spitzer.caltech.edu and http://www.nasa.gov/spitzer.

PD: The original PR is located here.

PD II: Image with additional information here.

Brown dwarfs are sometimes called “failed stars”. They are born from interstellar clouds following processes closely related to the formation of normal stars. But brown dwarfs lack mass enough to light up nuclear reactions in their interiors. Thus, they cannot be considered true stars and in fact some properties reassemble those shown by giant planets. Uncovering proto-brown dwarfs, i.e., brown dwarfs in their very first evolutionary stages, is a long-sought hit. A recent study has found the best proto-brown dwarf candidate known to date. Calar Alto has contributed key data to this finding…

* * *

The first brown dwarfs were discovered in 1995. A lot has been learned about them since that date, but the formation mechanism (or mechanisms) is a hotly debated issue. The processes leading to the birth of a brown dwarf are, no doubt, related to those forming normal stars, but many details are lacking. Stars and brown dwarfs evolve very rapidly during their first stages, what makes quite difficult to catch them in the very process of birth. This challenge is even more difficult due to the fact that extremely young objects are still embedded into the gas and dust clouds from which they condense. This is the “Class 0/I stage”, in the classical evolutionary scheme of young stellar objects.

A recent international study leaded by David Barrado y Navascués (LAEX-CAB, INTA-CSIC) has identified the best proto-brown dwarf candidate known to date. Their search begun analysing data obtained with the Spitzer infra-red space telescope. They were looking for low-luminosity bodies (dimmer than one tenth of the solar energy output) still embedded within dense nebular cores. A preliminary list of candidates resulted from this search. As stated by Barrado y Navascués, “we acknowledge the fact that we are exploring uncharted water, and that the contamination by extragalactic sources and very extincted stars can mimic the properties of a potential sub-stellar object”. For this reason they “carried out an exhaustive follow-up at different spectral ranges”.

The multi-band analysis was carried out retrieving data from public data bases and, also, making new observations at different observatories. Spitzer, 2MASS and CFHT archive data were used, and observing campaigns were performed with the IRAM 30m radiotelescope (Granada, Spain), ESO’s Very Large Telescope (Chile), Caltech Submillimetre Observatory (Hawaii, USA), Very Large Array (New Mexico, USA) and Calar Alto Observatory (Almería, Spain). Calar Alto data were obtained in 2007 with the Zeiss 3.5 m telescope equipped with Omega 2000 infrared camera. According to the researchers “CAHA data were key to confirm the nature of the object”, by providing near-infrared high spatial resolution imaging, that turned out to be the best proto-brown dwarf candidate yet known.

This object, known as SSTB213 J041757, is placed in Taurus constellation, inside the dark cloud Barnard 213, at a distance of 450 light-years (140 parsecs). CAHA imaging has shown that it is a double object, with both components being compatible with the status of Class I proto-brown dwarfs.

Some conclusions can be drawn from this work. In relation to the formation mechanism, the researchers state that “if the source is really associated with a proto-brown dwarf, our observations strongly suggest that it was not formed through the ejection scenario, but rather in a similar way to low-mass stars”.

More observations and work will be needed to find more proto-brown dwarf candidates, and to definitely clarify the nature of these first examples. No doubt this research team will offer new and exciting results in this field, in a near future.

The research described in this press-release was accepted for publication by Astronomy and Astrophysics journal in September 2009. The paper is signed by D. Barrado y Navascués, M. Morales-Calderón, Aina Palau, A. Bayo (all them from LAEX-CAB, INTA-CSIC), I. de Gregorio-Monsalvo (ESO), C. Eiroa (UAM), N. Huélamo (LAEX-CAB, INTA-CSIC), H. Bouy (IAC), Ó. Morata (Academia Sinica & NTNU), and L. Schmidtoreick (ESO).
See Calar Alto Press release and the images here (in English, Spanish and German)

I have watched a very interesting movie last weekend: “Ágora”, by the Spanish-Chilean director Alejandro Amenábar. It is a story about a very interesting character, the astronomer Hypatia, who live in the IV-V centuries, during the end of the Roman empire. We know for sure few things about her life and death. She was killed during by Christian zelots during these turbulent years, when paganism (and the classical culture) was dying, and a new order and way of understanding the world was appearing

As a matter of fact, I do not care whether the story in the movie is accurate or is the re-interpretation of several historical facts using our own situation. What really matter to me are two facts:

First, Hypatia herself, as scientist. The way she understands her environment, her compromise with knowledge. Her humility recognizing her limitations and, above all, her flexibility to reevaluate her initial assumptions and to challenge what she believed previously to be the truth.

Second, the intolerance, then and now. There are always bigots (whether religious extremist, political, moralist or otherwise) trying to restrict knowledge and freedom. They know science and culture are barriers against barbarism, and they are one of the first targets.

I have read in the newspaper that the movie might not be distributed in USA, since some people believe it is anti-christian (it is not), despite its quality, the important casting and the amazing reconstruction of the ancient city of Alexandria, where it takes place. It would be a shame if the intolerants win again.

For those of you who didn´t have the opportunity to watch “Cosmos”, by Carl Sagan, I do recommend to try to, at least, have a look at the episode discussing the destruction of the Library and the Serapeum.

After 1600 years, Hypatia is still a example: of what a scientist ought to be, but, above everything, how a human being has to behave.

Información en español

I have to confess that sometimes I am very tired of my trips: conferences, workshops, meetings, observing runs… I hate airports, I do not like the security and the waste of time, and I would prefer to avoid the effect of all these trips in my social life, since I spend a significant amount of time away.

However … sometimes (or many) is wonderful.

I am in Barcelona, for the conference “Pathways toward habitable exoplanets”. Today, a member of the Corot/HARPS team has announced the confirmation by radial velocities techniques of the first super-planet: Corot-7b, and the detection of a second planet around the same star. they should have masses of 4.8 and 8.4 earth masses, and due to their very short orbital periods (0.89 and 3.7 days), they should be very exotic, with a huge difference between the hemisphere always facing the star (about 200 K) and the night side, almost at 50 .

Información en español

If months ago (sorry for not being able to write more often: work, trips, vacations…) I wrote about writing proposals and the efort it implied, now I am collecting the benefits: the observing time.

I applied and obtained a fair amount of hours in service mode with the new and shine Spanish 10 m telescope GTC. I submitted the Observing Blocks (the instructions about how to observe) yesterday and since the proposal was approved with a good ranking, the data will be collected during the incoming months

And I am now at the William Herschel Telescope, observing very young objects we discover using the Spitzer Space Telescope. They are heavily embedded by material and they seem to be pulsating, but we do not know what they really are. So we are taking infrared spectra in order to be able to classify them and to have an idea about what is going on.

I have to confess I am quite tired, but fortunately most of the work is being done by my student Pablo. In any case, it is going to be a long night…

Astronomy, like any other science, works under the system of peer-review. It means that nothing is published in a prestigious journal without having the external examination of at least one specialist in the field, a person who is not connected directly with the research described in the paper. The same system is valid for the observing proposals. Most observatories (at least the important ones) have a panel of experts which read all the submitted proposals and grade them, granting time to the best and feasible ideas. See Franck Marchis’ description about how it works with the European Southern Observatory. The goal is to try to remove subjectivity (difficult, since we are humans) and to make the best out of the available observing time.

So, now to the question formulated in the title…

At least in this occasion I have been lucky, or very good, or the Olympic gods have smiled at my team. In the same day we have received the answer from Calar Alto, La Palma (both in Spain) and Subaru (Hawaii, USA) and we have received a fair amount of nights in this telescopes, including the newest and hopefully most powerful in the optical and near-IR from the ground: the Spanish 10, GTC.
I guess next Fall I will be busy observing…

Yes, it has been worth it.

Running, I feel I am always running everywhere, trying not to miss the next step, almost at the verge of a disaster. Today, the train from Palermo to the airport broke and I almost didn’t arrive on time to catch the place. But ts departure was delayed and I was afraid I would not be able to change planes in Rome. I had to run across the terminal, to find out that the second flight was delayed. At least I know that, today, I will reach my destination: finally, home. But, in a sense, this way back home has been a kind of small Odissey, a metaphore of life.

The last six months or so have been, work-wise, to most strange in my professional career. Meetings, projects, justifications, trips, proposals, committees … one after another, without pause. Finally, it seems I have achieved, more or less, all the goals I had in mind, and most of my commitments (some of them fun) are over. So, I expect from now on to have more time for science and for my students. And I hope I will not have to go through any period like this one.

In the JENAM (European Astronomical Society Meeting), in England … plenty of wonderful results. Of course, from my point of view, the most important is the announcement by Michael Mayor of a new exoplanet, with an extremely low mass, only twice the earth value (although it depends on the inclination of the orbit).

I have a kind of déjà vu. I was in Florence 14 years ago when he announced the discovered the first exoplanet orbiting around a solar type star. It amazement how far we have gone in these few years, and the group of Prof. Mayor has played a key rôle on this very exciting area.

Link to the info in Spanish.

After a quite a hectic month, full of proposals and paperwork, I can go back to science. ¿Really?

I had my last deadline last April 10th, for the Subaru telescope. It was also the Easter week, but I work everyday on this and finishing the first version of my next book. So, I thought I would be able to go back to do real science after this date. As usual, I was wrong.

I have been busy with the justification of my annual budget for the JWST/MIRI (an instrument for the next space telescope) and with ideas for the E-ELT.

Next week I have the meeting of the European Astronomical Society, which will be held in UK, and the following I am coming back there for the JWST/MIRI consortium meeting.

All these things are fun, but it has been quite a lot since I have seen my last astrophysical data…