When a star like our sun dies, all remain is an exposed, dense core – a remnant white dwarf. It is assumed majority of the star’s evolving bodies will be devastated altogether after its immense explosion. However, there was a breakthrough observations of an exoplanet orbiting its white dwarf star, which might bring hope to the very existence of life surrounding death stars. So, is there actually any chance life can sustain after the supernova of its host star? This question has endlessly plagued scientists around the globe since the invention of powerful telescopes. “A planet orbiting a white dwarf presents a promising opportunity to determine if life can survive the death of its star,” according to Cornell University researchers. All the sequence-type stars, including our sun, sooner or later will finish up as a dead, bare copse. Hence, delving for the conservation of survival on exoplanets might devulge the foreseen destiny of our mankind.

In a recent report published in the Astrophysical Journal Letter, the upcoming James Telescope often called a successor to Hubble, held promise for signatures of life on Earth-like planets orbiting white dwarfs. This new generation telescope will allow scientists to practically track down any indicator of distant planets and investigate the atmospheric composition of those alien worlds. 

Method of detecting life on alien planets surrounding the white dwarf  

The universe is enormous, there are approximately one hundred billion to one trillion detected stars teeming with trillion of habitable planets floating in this deep, hollow space – meaning for every grain of sand on Earth. Besides, since white dwarfs are very small, they’re generally rather dim, having low luminosity despite very high surface temperature – thus, foraging white dwarfs among these loads of stars is another problem. Hence, the task of detecting life on every single planet orbiting these white dwarfs is exceptionally onerous. 

However, the dominant of James Webb Space Telescope, scheduled to launch in October 2021, will be potential to provide astronomers with unprecedented views from the ground over the infrared wavelength of light. This instrument will promise to study the atmosphere of distant worlds around white dwarfs and other stars. “When observing Earth-like planets orbiting white dwarfs, the James Webb Space Telescope can detect water and carbon dioxide within a matter of hours,” MacDonald said. “Two days of observing time with this powerful telescope would allow the discovery of biosignature gases, such as ozone and methane.”

Identifying the planet’s atmospheric composition will afford us an adequate understanding of whether life is possible out of the earth. A planet orbiting a small star produces a strong atmospheric signal when it passes in front, or “transit” its home star. White dwarf despite being packed down to the size of the Earth-size planet after the star shedded its outer layer, it contains as much mass as the sun. However, when orbiting planets do pass in front of these diminutive stars, they block a significant amount of light from the white dwarf. Thus, detecting exoplanets and studying their atmospheres become easier. 

First Giant Survivor Planet 

The astonishing discovery of the first giant planet candidate, known as giant ‘survivor’ planet, transiting a white dwarf WD 1856+534b, was lately announced by NASA’s Transiting Exoplanet Survey Satellite (TESS). Over the observations of this transiting giant planet orbiting the white dwarf every 1.4 days, researchers confirmed this planet is a gas giant and therefore not be able to sustain life. They detect its existence by observing and measuring the periodic dimming of the white dwarf caused by the planet candidate transiting by the star in its orbit. This gas giant was determined roughly the same size as Jupiter and no more than 14 times as massive. 

A team of astronomers detect the amount of hydrogen, oxygen, and sulphur are similar to those found in a deep atmospheric layer of the icy, giant planets like Uranus and Neptune. 

Detecting a planet that still has a sign of evolving around the white dwarf is quite astounding. Most planets orbiting a sun-like star would have been completely destroyed during its home star’s cataclysmic upheaval, a supernova, before turning into its white dwarf state. The existence of this planet suggests that smaller rocky planets which could harbour life may uphold the possibility to exist in the habitable zones of a white dwarf. “We know now that giant planets can exist around white dwarfs, and evidence stretches back over 100 years showing rocky material polluting light from white dwarfs. There are certainly small rocks in white dwarf systems,” MacDonald said. “It’s a logical leap to imagine a rocky planet like the Earth orbiting a white dwarf.” 

The finding for WD 1856+534 system indicates gas giants can be scatted into tight orbit without being tidally disrupted, tempting the search for small transiting rocky planets that can sustain life around white dwarfs. 

“WD 1856b somehow got very close to its white dwarf and managed to stay in one piece,” said Andrew Vanderburg, an assistance professor of astronomy at the University of Wisconsin Madison. “The white dwarf creation process destroys the nearby planet, and anything that later gets too close is usually torn apart by the star’s immense gravity. We still have many questions about how WD 1856b arrived at its current location without meeting one of those fate.” This thought motivates scientists to keep wrapping their head around the problem to unravel the knot.

The implication of finding signatures of life on exoplanets orbiting a white dwarf is an enthusing, yet a profound task. Most stars, including our sun, will one day end up as white dwarf. Therefore, searching for the possibility of life the white dwarf’s orbiting planets not only show the incredible tenacity of life, but perhaps also a glimpse to our future.  

Bibliography

Anderson, P. S. (2019, May 19). How some planets can survive their stars’ deaths. Retrieved from EarthSky: https://earthsky.org/space/small-rocky-planets-most-likely-to-survive-star-death

Cornell University. (2020, September 16). Can life survive a star’s death? Webb telescope can reveal the answer . Retrieved from ScienceDaily: https://www.sciencedaily.com/releases/2020/09/200916113604.htm

Maynard, J. (n.d.). Could Life Survive the Death of a Star? Retrieved from Medium: https://medium.com/the-cosmic-companion/could-life-survive-the-death-of-a-star-4c080d265260

Rogers, J. (n.d.). NASA spots first possible ‘survivor’ planet hugging a white dwarf star. Retrieved from FOX NEWS: https://www.foxnews.com/science/nasa-spots-first-possible-survivor-planet-hugging-white-dwarf-star

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