Astronomers have identified a potential “ice cold Earth” – HD 137010 b – a rocky exoplanet orbiting a star 146 light-years away. The discovery, announced in late January , offers a tantalizing glimpse into a world that, while potentially habitable, presents a significantly chillier environment than our own.
The exoplanet candidate, HD 137010 b, is estimated to be slightly larger than Earth, with a mass approximately 1.2 times greater. Its orbital period is remarkably similar to Earth’s, completing a revolution around its star in roughly 355 days. Researchers estimate a 51 percent probability that the planet resides within the habitable zone of its star – the region where liquid water could theoretically exist on the surface.
However, the star HD 137010 is not a G-type star like our Sun. It’s a K dwarf, approximately 70 percent the size and mass of the Sun. This difference is crucial. K dwarfs are cooler and dimmer than our Sun, and crucially, they have significantly longer lifespans due to their more efficient hydrogen consumption. In fact, HD 137010’s lifespan is projected to exceed the current age of the universe.
The discovery is significant because HD 137010 b is the first planet candidate with Earth-like radius and orbital properties orbiting a Sun-like star that is bright enough for detailed follow-up observations, according to the research team. This brightness is key; it allows for more precise measurements and analysis of the planet’s atmosphere and surface conditions.
Uncovering a Distant World with Kepler Data
The existence of HD 137010 b was teased out from data collected by NASA’s now-retired Kepler Space Telescope, using a technique known as the transit method. This method relies on observing the slight dimming of a star’s light as a planet passes in front of it. The amount of dimming reveals the planet’s size, and the frequency of transits reveals its orbital period.
Confirming the planetary status of HD 137010 b requires observing multiple transits. Because the planet’s orbit is similar to Earth’s, this process will take several years of observation. Currently, astronomers have only observed a single transit, making it a “candidate” planet rather than a confirmed one.
A Frigid Climate, But Potential for Liquid Water?
Despite the potential for liquid water, the conditions on HD 137010 b are likely to be extremely cold. The planet receives less than a third of the energy that Earth receives from the Sun. Estimates suggest a surface temperature ranging from -68 to -85 degrees Celsius (-90 to -121 degrees Fahrenheit) – colder than Mars.
However, the possibility of liquid water isn’t entirely ruled out. Researchers suggest that a moderately CO2-rich atmosphere could potentially create a greenhouse effect sufficient to maintain liquid water on the surface. But even with a CO2-rich atmosphere, the planet could become trapped in a “snowball” climate – a completely glaciated state where the highly reflective surface bounces incoming sunlight, further reducing temperatures to around -100 degrees Celsius.
Implications for the Search for Life
The discovery of HD 137010 b is more than just the identification of another exoplanet. It demonstrates the feasibility of detecting temperate, Earth-sized planets orbiting Sun-like stars, even with just a single observed transit. This is a crucial step forward in the ongoing search for potentially habitable worlds beyond our solar system.
While HD 137010 b itself may be a frozen world, its discovery highlights the potential for other, more temperate planets to exist around similar stars. Future observations, potentially with next-generation observatories like the European Space Agency’s PLATO, will be crucial for confirming the planetary status of HD 137010 b and characterizing its atmosphere and surface conditions.
The research also suggests that HD 137010 b may not be alone. Other planets could exist within the system, potentially forming a “solar system-like architecture” with multiple planets orbiting the star, including a possible Jupiter-sized gas giant further out.
Even a frozen world isn’t necessarily devoid of life. Earth itself experienced multiple “snowball” periods throughout its history, and life persisted even under those extreme conditions. The discovery of HD 137010 b underscores the resilience of life and expands the range of environments where it might be found.
The findings are detailed in a study published in The Astrophysical Journal Letters.
