Manuel Aravena – Emol
May 9, 2024
Although we have built much of our astronomical knowledge through observations of “visible” light (that which we see with our eyes), this corresponds to only a small part of the electromagnetic spectrum. Most of the radiation coming from the Universe cannot be seen with optical telescopes like Galileo’s, that is, most of the light is “invisible” to our eyes.
In fact, the electromagnetic spectrum includes radiation, or photons of light, ranging from the so-called Gamma rays, through X-rays, ultraviolet, visible, infrared, submillimeter to radio waves. Therefore, a “holistic” vision that provides us with an interpretation of the physical phenomena that occur in the Universe needs observations at all wavelengths.
Fortunately or unfortunately (it depends on how you look at it) much of the radiation that comes from outer space is blocked by our Earth’s atmosphere, making it almost impossible to observe X-rays and ultraviolet rays from Earth, and even more difficult, those in the infrared range. Fortunately, because the atmosphere protects us from this radiation, life on Earth is permitted, which is unfortunate for astronomical observations.
Of particular astrophysical interest – in recent times – is infrared light, through which it is possible, for example, to observe planets directly, measure the existence of atmospheres and their composition, and/or detect biomarkers in the search for life. Likewise, it is possible to measure gas clouds where there is star formation, black holes, the formation processes of the first stars and galaxies, among others.
For this reason, the construction of large infrared observatories has been promoted, including the recent James Webb (JWST), Euclid, and the Nancy Grace Roman (expected to be launched in 2027), space telescopes, and even the ALMA observatory, which observes from the far infrared to submillimeter. In fact, the next generation of giant telescopes, including the 39-meter-diameter “Extremely Large Telescope” (ELT) to be built in northern Chile, will operate largely in the near- and mid-infrared.
Among these projects is the TAO (Tokyo Atacama Observatory), which was developed by the University of Tokyo, Japan, during the last decades, and which was finally inaugurated a few days ago. In the scientific workshop that was held at the PUC the day before the inauguration, we learned a little more about this project.
The 6.5 meter diameter telescope is specifically designed to observe in the infrared and will be located on the top of Chajnantor Hill at 5,640 meters high, making it the highest observatory in the world. As a reference, TAO will be located in the Atacama Astronomical Park, above the ALMA observatory, which is located at 5,000 meters above sea level on the Chajnantor plain. The main reason for locating TAO at such a height is to avoid much of the atmosphere, including clouds, water vapor, and atmospheric turbulence. While TAO will not be able to produce deeper or better fidelity images than those we know from the James Webb Space Telescope, it will give us a unique opportunity to access infrared observations more easily and frequently, such as for observing variable stars, novae, supernovae, amongst others, and at longer wavelengths than those accessible to the JWST.
Due to the difficulty of having scientific personnel at 5,600 meters above sea level, TAO will be operated remotely most of the time, similar to the ALMA telescopes, from Santiago or even from Japan. Japanese and Chilean astronomers will be able to access observing time in the usual way, sending proposals that are reviewed by a panel of experts on the subject and then assigning those that appear to be most important, or of high priority. The TAO project promises to encourage collaborations in astrophysical and instrumentation projects between the Japanese and Chilean communities. An example of this is the current development of a high-resolution infrared spectrograph called TARdYS, led by the UC Astro-Engineering Center, which is designed for the characterization and detection of exoplanets like Earth around low-mass stars.
It should be noted, however, that until the arrival of the ELT at the end of this decade, the James Webb Space Telescope will be the most effective observatory for detailed studies of astronomical objects, given its large size of 6.5 meters and the absence of atmospheric turbulence in space. This is particularly important for deep field observations and early galaxies.
Astronomers in Chile have a unique advantage, by having access to these world-class facilities, equivalent to the best existing laboratories. This has placed astrophysical research carried out in Chile at the highest global level, generating collaborations with prestigious foreign institutions. It is therefore important to continue investing in science and astronomy, in particular for the development of the country.
By Manuel Aravena, academic and researcher at the Institute of Astrophysical Studies UDP, in Emol.