Star eats cloud (or “In Orion it’s no time for joking”)

Getting data from a telescope can be very exciting. Basically, because getting them and interpreting them is a whole process that can take several years… Since the observation program is designed, the time is requested, it is granted (or not), the observations are carried out, the data is obtained and, finally, the information is analyzed and extracted… the whole process is a marathon full of uncertainty and challenges.

Image 1: Red-green-blue image showing three different velocities of the gas associated with the heart of the Orion cloud.

Of course, it can be data from a ground-based telescope or a space telescope.

Or, as in our case, it can be both.

SOFIA: Ground or space telescope? Well, both!

We’re talking about a telescope installed in a modified NASA Jumbo 747 aircraft. It is called SOFIA (Stratospheric Observatory for Infrared Astronomy) and, at each observation, it takes flight to the stratosphere, about 13 km above sea level (a couple of km above commercial flights) and goes back down, perching at its Californian airport and returning home to rest.

Each observational flight lasts about 10 hours, and the data obtained are very important, among other things because, right now, there is no instrument outside the Earth (that is, above the atmosphere and its nefarious turbulence) that observes in the far infrared, a range of the electromagnetic spectrum critical to understand how stars form and interact with the interstellar medium.

With a mirror of 2.5 meters in diameter, SOFIA is the name of the whole set. And Javier R. Goicoechea says (I will introduce him in a moment) that it is impressive to see how the whole plane can tremble from the turbulence while the intelligent hydraulic structure that supports the telescope and its instruments compensates for those alterations and remains perfectly still (I would love to change myself for the instrument, I want one of those compensators for my air trips).

Image 2: SOFIA (The Stratospheric Observatory for Infrared Astronomy)

SOFIA is 80% NASA (which has built and operates the observatory) and 20% DLR (the German space agency).

For starters, getting a plane to fly with an impressive door open (yes, you read that right, open), is already quite a feat. That it does so, in addition, with a team formed by telescope and instrument of about 20 tons of weight, also has its complications.

But let’s get to deeper.

It turns out that Javier R. Goicoechea, senior scientist at the Institute of Fundamental Physics (IFF) of the CSIC, participates in an international team that studies the destructive effects of ultraviolet radiation and the strong winds emitted by young massive stars in the interstellar clouds where they are born. Last year the team obtained 10 observation flights in order to map the Orion cloud in the emission of ionized carbon, the brightest emission from interstellar gas. As he states, “SOFIA is like a space telescope, in the sense that it allows us to observe in the infrared above 99% of atmospheric water vapor, but after a night of observations, astronomers and telescope land on the ground to regain strength.”

Image 3: Javier R. Goicoechea (IFF-CSIC) in full flight and data collection. In the background is Jürgen Stutzki (University of Cologne, Germany), co-Principal Investigator of the GREAT instrument.

The results have been really amazing.  

WHAT A PROGENY! Daughters eating parents.

As we have told in other articles, dense clouds of gas and dust are the birthplace of the most massive stars in the galaxy. The mass is concentrated, condensed, the reactions begin in the nucleus and… A star is born!

The more mass the star has, the more violent it is and the less time it will live. The fact is that we know that, in this area of Orion, there are very massive stars -the Trapezium cluster- that are “sweeping” the surrounding material, undoing the cloud that saw them born with their powerful stellar winds and their intense ultraviolet radiation. A kind of “parentophagy” (I know this word does not exist…).

The data obtained with SOFIA have revealed that this happens much earlier than previously thought. In just a few hundred thousand years the winds coming from the most massive star of the Trapezium have pierced the natal cloud, creating a huge bubble, whose expansion and movements have been revealed thanks to the 3D observations obtained (have I not said that an amazing 3D film has been made with the data?). A single star giving shape to one of the most observed and known regions of the sky.

What a blow.

Measuring speeds for the first time

The results obtained have given, for the first time (yes, we always say that because it is very cool in astronomy to say “as never before”, “for the first time”, “with an unprecedented resolution”, and again and again)… For the very first time a 3D map of the gas velocities in the studied area has been made. Thanks to the spectroscopy of very high spectral resolution, maps of the speed of the expanding gas bubble have been obtained, resulting in this amazing video:

In short. Everything is going faster than predicted, in every way. The young massive stars determine, much earlier than previously thought, the shape and evolution of the interstellar environment that saw them born, ravaging and cleaning, with their strong stellar winds, the entire region that surrounds them. That means they sweep away the interstellar material needed for the formation of new stars.

For Javier R. Goicoechea, “It is incredible that after more than 400 years observing the great Orion Nebula, we have now been able to understand that the winds coming from the most massive stars blow the surrounding cloud and give it that morphology so recognizable“.


Image 1: Red-green-blue image showing three different velocities of the gas associated with the heart of the Orion cloud. The wind from the most massive stars has created a bubble (in black) and prevents the formation of new stars in its environment. At the same time, the wind sweeps the gas from the edges (in color), creating a shell of thin gas around the bubble and where perhaps a new generation of stars can form. Credits: NASA/SOFIA/Pabst et al.

Image 2: SOFIA (The Stratospheric Observatory for Infrared Astronomy) flying over the California sky. The telescope can be seen inside the open cavity at the rear of the aircraft. Credit: NASA/Jim Ross

Image 3: Javier R. Goicoechea (IFF-CSIC) in full flight and data collection. In the background is Jürgen Stutzki (University of Cologne, Germany), co-Principal Investigator of the GREAT instrument.

More information:

Paper: C. Pabst, R. Higgins, J.R. Goicoechea, D. Teyssier, O. Berne, E. Chambers, M. Wolfire, S. Sury, R. Guesten, J. Stutzki, U.U. Graf, C. Risacher, A.G.G.M. Tielens. Disruption of the Orion Molecular Core 1 by the stellar wind of the massive star Ɵ1 Ori CNature. DOI: 10.1038/s41586-018-0844-1.

CSIC Press Release (in Spanish):  Los vientos estelares de las estrellas masivas dan forma a la nebulosa de Orión

Link to the SOFIA press release with 3D videos

Hydrocarbons open bar in Orion

Orion’s skin

New observations of the Orion B nebula reveal the anatomy of a star-forming reservoir

Originally published in Spanish on the Naukas website: Estrella come nube (o «En Orión no está el horno p’a bollos») (2019/01/14).