in search For exoplanets, astronomers and astrobiologists generally follow a policy of “follow the water.” This is due to the search for planets orbiting the star’s habitable zone (HZ), where conditions are warm enough for liquid water to flow on their surface.
The reason is simple: Water is the only known solvent capable of supporting life and required for all life on Earth. But since the 1970s, scientists have speculated that there might be a class of rocky planets in our universe completely covered in water.
Search for “water world”
With the explosion in confirmed exoplanets, scientists were eager to find examples of this type of planet, so they studied them more closely. Thanks to an international team of researchers led by the Institute for Research on Exoplanets (IREX) at the University of Montreal, an exoplanet has recently been discovered that orbits within the habitable zone of its system and can be completely covered in the deep ocean.
This “ocean world” (also known as the “water world”) can reveal more about the nature of habitation when it is the subject of follow-up observations with the James Webb Space Telescope (JWST).
The international team was led by Charles Kedio, a doctoral student at the University of Montreal and a member of IREX. He was joined by a team of 55 astronomers and astrophysicists, including researchers from Canada, France, the United States, Japan and Brazil.
As they explain in their paper, which appeared on August 12 in Astrophysical Journalthe exoplanet (TOI-1452 b) orbits within a binary system located in the constellation of Draco about 100 light-years from Earth.
The system consists of two M-type stars (red dwarfs) orbiting closely each other, at 97 astronomical units (AUs), or about two and a half times the distance between the Sun and Pluto. The possibility of an exoplanet orbiting one of these stars was originally ventured based on data acquired by the Transiting Exoplanet Survey Satellite (TESS).
Based on TESS data, astronomers note that the exoplanet experienced a slight decrease in brightness every 11 days, estimating that its diameter is about 70 percent larger than the diameter of Earth. Cadieux and colleagues made follow-up observations (a function routinely performed by IREX) using the Planètes Extrasolaires en Transition et en Occultation (PESTO) camera on a 1.6-meter telescope at the Observatoire du Mont-Mégantic (OMM) – part of the University of Montreal.
Due to their low brightness and proximity, the two TOI-1452 stars appeared as a single point of light when observed by TESS. However, PESTO’s resolution is high enough to distinguish the two objects, and the images it obtained confirmed that an exoplanet orbited TOI-1452. Subsequent observations were made by a team from the National Astronomical Observatory of Japan (NAOJ) using the 8.2-meter Subaru Infrared Light Telescope in Maunaki, Hawaii. As co-author Rene Doyon, professor at the University of Montreal and director of iREx and OMM explained in an IREX press release:
“I am very proud of this discovery because it shows the high efficiencys From our researchers and devices. It is thanks to OMM, a special tool designed in our laboratories called Spiroand an innovative analytical method developed by our research team that enabled us to discover this unique exoplanet.”
“OMM has played an important role in confirming the nature of this signal and estimating the radius of the planet,” Cadeaux added. “This was not a routine check. We had to make sure that the signal detected by TESS was indeed caused by an exoplanet orbiting TOI-1452, the two largest stars in that binary system.”
After confirming the existence of an exoplanet and obtaining estimates about its size, the team turned to the SpectroPolarimètre Infra-Rouge instrument (SPIRou), a near-infrared spectrometer installed on the telescope of Canada, France and Hawaii. Largely designed in Canada, SPIRou is ideally suited for studying low-mass stars such as the TOI-1452 binary components because they are much brighter in the infrared wavelength. Despite this, it took more than 50 hours of observing time to produce estimates of the planet’s mass (nearly five times the mass of Earth).
The next big challenge was data analysis, which was performed using the line-by-line (LBL) analytical method developed by Etienne Artigau and Neil Cook (also with IREX). This allowed the team to identify the weak signal produced by an exoplanet in the SPIRou data.
Finally, doctoral students Farbod Jahandar and Thomas Vandal from the University of Montreal analyzed the SPIRou data to learn more about the composition of the host star, which is useful for constraining the planet’s internal structure. Based on their estimates of radius, mass, and density measurements, astronomers hypothesized that TOI 1452 b is likely a rocky planet.
But those same estimates led them to conclude that TOI 1452 b could be covered in a thick layer of water, similar to the largest moons of Jupiter, Saturn, and other icy bodies in the outer solar system. This is supported by in-house modeling by Mykhaylo Plotnykov and Diana Valencia of the University of Toronto, which suggests that water may make up as much as 30 percent of the mass of TOI 1452 b, which is also similar to satellites such as Jupiter’s moons Europea, Ganymede and Callisto; Saturn’s moons Titan, Dione and Enceladus.
The first oceanic planet?
In recent years, astronomers have discovered hundreds of similar exoplanets with radii and masses between Earth and Neptune but whose densities are significantly lower. This indicates that a large part of the mass of these exoplanets is made up of volatiles such as water, which leads to the nickname “ocean planets”. As Cadiux explained, this latest discovery may be the first such planet ever discovered:
“TOI-1452 b is one of the best candidates for an ocean planet that we have discovered so far. Its radius and mass indicate a much lower density than one might expect for a planet composed primarily of metal and rock, such as Earth.”
Given that TOI-1452 b orbits within the host star’s HZ, it is unlikely to have an icy surface, which means it could have oceans several kilometers deep. This makes TOI-1452 ba an ideal candidate for further observations with JWST, as it is one of the few known temperate planets that also exhibits ocean planet characteristics.
Its proximity to Earth also makes it a good candidate for atmospheric characterization, which is a Web thing Very good – as evidenced by the spectra obtained twice from WASP-59 (confirming the presence of water and carbon dioxide).
To make matters even better, TOI-1452 is located in an area of the sky that Webb can observe year-round, making it ideally positioned to keep track of observations.
“Our observations using the Webb Telescope will be essential to better understanding TOI-1452 b,” says Doyon, who is also the principal investigator for Near Infrared Imaging and Slit Spectrometry (NIRISS), the Canadian Space Agency’s JWST contribution. “As soon as possible, we will book time on the web to witness this strange and wonderful world.”
This article was originally published on universe today by Matt Williams. Read the original article here.