in Sierra de los Filabres in Almeriaat an altitude of 2168 meters, is one of the largest hunters exoplanets world: CARMEN IS. This is not about some folklore and has nothing to do with a female name. In fact, it matches the initials Calar Alto High-resolution search for M dwarfs with exo-Earths with Eshel near-infrared and optical spectrographs. It is located at the Calar Alto Observatory in Almería but is funded and run by German Latin American Consortium to which belong a total of 11 institutions from both countries.
Since its discovery in early 2016, scientists from this consortium have met every 6 months summarize your work. One such meeting has just taken place for the first time in Almería, the province where CARMENES does its great work. There, just over 60 kilometers from the instrument, they outlined the progress made and discussed a future in which many more exoplanets remain to be discovered.
And that’s what CARMENES was designed to fill in a huge gap in exoplanet research. Although these kinds of discoveries have been made since 1995, most of them were planets located around stars like our Sun, which left a very large gap as other very interesting ones were expected to be found around red dwarfs.
The instruments that have existed so far have had great limitations for this kind of observation. That’s why CARMENES was specially created to search around you. And he achieves this. So far they have found about 60 exoplanetsover 100 studies have been published and this is just the beginning.
Keys to finding exoplanets
There are many methods for detecting exoplanets or, equivalently, planets outside our solar system. The two most commonly used are transit and radial speeds.
The first is based on the fact that when an exoplanet passes between its star and Earth, it causes the light that reaches us of which decreases periodically. We must not forget that, like the Earth around the Sun, exoplanets periodically travel around their own bodies. Therefore, detecting these fluctuations in luminosity can help us know that there is an exoplanet there and, in addition, learn a lot of facts about it.
On the other hand, radial speed It is based on a different phenomenon. And the fact is that in the same journey around its star, the gravitational attraction exerted by the planet causes oscillations in it and small changes in its spectrum. This is basically what CARMENES does, but under very different conditions than other exoplanet hunters.
What distinguishes CARMENES?
Need explore red dwarfs due to the fact that they were practically not studied. explained it hypertext Ignacy Ribas, Director of the Institute for Space Studies of Catalonia (IEEC) and Research Fellow at the Institute of Space Sciences (ICE) CSIC. “At that time they were made polls radial velocity, especially for solar-type stars, and there was an uncovered region.
And, in fact, it was interesting to explore this area, because it presented very important opportunities. The signal that the planet sends to its star inversely proportional to its mass: the smaller it is, the greater the signal, so a small planet next to a large star is difficult to see, and a small planet in a small star is easier to see, ”explains the astrophysicist. “On the other hand, since the star is less luminous, the orbital distance of the habitable zone is closer to the star and shorter orbital period“.
It should be noted that the habitable zone is a zone in which exoplanets are neither too close nor too far from their star for water to be in a liquid state. In this case, these orbital periods could be 10, 15, or 20 days, so “by observing less time, you have more likely to find something“.
It is clear that these are interesting stars, but before the appearance of CARMENES they could not be properly studied. This is because they are very cool and active stars that emit light in near infrared. Most of the tools that have been used to search for exoplanets have worked in visible spectrum. Therefore, no matter how they will watch to these stars, they couldn’t see them.
Interference elimination
CARMENES is equipped for observation in the infrared as well as in the visible range. And this is very positive, as it helps to separate the tares from the grains or, more precisely, the exoplanets of stellar activity. “Sign of the planet must have the same amplitude or intensity regardless of wavelength in which you look at it,” says Ribas. Therefore, it does not matter whether it is observed in the infrared or in the visible range. The result should be the same. “On the other hand, stellar activity has chromatic spectra in which the spectrum is larger in the blue portion and smaller in the red portion.” This makes differentiation very easy. If it remains the same, it will be an exoplanet, if it changes, it will be stellar activity.
Past, present and future of this exoplanet hunter
CARMENES was conceived to analyze what is known as interview 300 starsin search of their corresponding exoplanets.
Initially, it was the only instrument capable of analyzing red dwarfs. However, years have passed and many other tools have appeared. We can say that they are no longer the only ones, but they keep changing things. “There are larger and more accurate infrared instruments, but CARMENES has been able to put together an instrument that works very well with very good spectrum coverage from blue to red,” says a scientist interviewed by the tool. “In addition, Calar Alto was very generous, as he gave the consortium a lot of time, with 750 nights of observation“.
This allowed them to be very competitive. Enough to discover 60 exoplanets and publish 100 studies. But these figures only apply to scientists in the consortium. There was an external collaboration that led to other very interesting discoveries. For example, they collaborated with Mission of TESSfrom NASA, which is dedicated to finding exoplanets through transit analysis.
“This is a NASA mission where we are collaborating to confirm the detection of exoplanets and measure their masses. We have confirmed about 25 TESS planets and it must be said that they are among the best, the ones we confirm are the ones that pass by to be observed with James Webb.”
Ignasi Ribas, Director of the Institute for Space Studies of Catalonia (IEEC) and Research Fellow at the Institute of Space Sciences (ICE) CSIC
In fact, CARMENES is highly respected and many non-consortium scientists are looking for work with him. For this reason, competitions have been announced so that any scientist can get time to research with this tool.
As for the observations of the consortium itself, 750 observation nights ended in 2020. Late 2021, 2022 and 2023 are part of the so-called interview legacy of CARMENES. On the other hand, out of the 300 stars they set out to analyze, there is still a lot to be explored. “We may have about 3 more years left,” Ribas calculates. “At least each star will have 50 measurements and we can see what planet they have and do a census and statistics.” In addition, they study tool designs to improve their accuracy. Have CARMENES for a while.
A perfect example of the legacy of CARMENES
We asked Ignasi Ribas if he had to leave one of CARMENES’ finds, what would it be? This is a difficult question because 60 exoplanets discovered during these years are very interesting. As he comments between laughs, it’s like choosing “who do you love more, dad or mom.” However, in the end, he is left with one that combines everything that this instrument represents.
“Perhaps what I enjoyed most was the discovery of one of the smallest stars we have observed: Teegarden. There we find two planets with the mass of the Earth. One is clearly in the habitable zone and one is very close. This is the best example of what CARMENES is capable of: an ultra-faint and small star, observed and crushed until they find planets the size of Earth.
Ignasi Ribas, Director of the Institute for Space Studies of Catalonia (IEEC) and Research Fellow at the Institute of Space Sciences (ICE) CSIC
And the fact is that there, at an altitude of 2000 meters above sea level in Almeria, science is looking intently at the universe. Clearly, he still has a lot to learn.
Source: Hiper Textual
