Star Devours Planet, Brightens Spectacularly

An illustration depicts a planet on its inevitable path of destruction, skirting the surface of its host star. Astronomers have gathered the first concrete evidence of a star, similar to a mature sun, swallowing a planet. The discovery was made possible through a range of telescopes including the Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory, the W.M. Keck Observatory, and NASA’s NEOWISE mission. The aging star in question, ZTF SLRN-2020, is approximately 10 billion years old. Over several hundred thousand years, it has slowly inflated and transitioned into a red giant, edging closer to its innermost planet. When the planet came perilously close to the star’s surface, escalating frictional forces propelled it to spiral inward. The timescale remains unknown, but eventually, the planet descended into the star’s core. As a result, the star swelled to four times its size and amplified its brightness over a hundred times. ZTF SLRN-2020 is situated roughly 12,000 light-years away in the constellation of Aquila. Image Credit: K. Miller/R. Hurt (Caltech/IPAC)

ZTF and NEOWISE detect the first observed instance of a star engorging its planet.

For the first time in history, astronomers have observed a star consuming a planet. This sun-like star, identified as ZTF SLRN-2020, is positioned about 12,000 light-years away in our galaxy, and it is believed to have devoured a Jupiter-sized gas giant. It was already known that aging stars would eventually consume their inner planets as they expand. This fate also awaits our sun, expected to absorb Mercury, Venus, and possibly Earth in about 5 billion years. However, this is the first instance of direct evidence of such a significant event.

Kishalay De (MS ’18, PhD ’21), a postdoctoral scholar at MIT, and the leading author of a new study about the findings published in Nature, explains, “The evidence that sun-like stars can consume their inner planets offers a crucial piece in our understanding of the destiny of solar systems, including our own.”

De and his colleagues gathered infrared data from the WIRC (Wide-field Infrared Camera) at Palomar’s Hale Telescope, which revealed the star was not only brightening in optical light but also in infrared light, indicating the presence of dust. Further data from NASA’s NEOWISE space telescope showed the star brightening in infrared light about nine months before ZTF recorded the drastic increase in optical light. Even after the optical light has dimmed, NEOWISE continues to register infrared light from the star.

Viraj Karambelkar (MS ’21), a grad student at Caltech and co-author of the study, states, “The infrared observations were a major clue that we were witnessing a star consuming a planet.”

After examining all the evidence, the team concluded that the dust detected by NEOWISE resulted from a planet spiraling into the star’s expanded atmosphere. As the planet skimmed the star’s surface, it extracted hot gas from the star, which then cooled and formed dust. Debris from the deteriorating planet also contributed to dust formation.

“The planet plummeted into the star’s core and was completely consumed. During this process, energy was transferred to the star,” De explains. “The star shed its outer layers to dissipate the energy. It swelled and brightened, and this brightening was what ZTF detected.”

The researchers drew parallels between this planetary engulfment and the merging of two stars, known as red novae. Karambelkar, who has observed eight of these eruptions using ZTF for his PhD thesis, adds, “Star mergers are thousands of times brighter than this event. This was another clue that we were observing a star devouring a planet. The brightening level was much fainter due to the small size of the planet.”

Mansi Kasliwal (MS ’07, PhD ’11), professor of astronomy at Caltech and co-investigator on the ZTF project, expresses her excitement, “This is simply spectacular. We are still stunned that we caught a star in the process of consuming its planet, something our own sun will do to its inner planets. That’s a long time from now, in five billion years, so we don’t have to worry just yet.”

To learn more about this discovery, refer to the following articles:

1. Astronomers Witness Star Devouring Planet in Possible Preview of Earth’s Ultimate Fate
2. Astronomers Witness a Star Devouring a Planet
3. Astronomers Detect a Star Devouring a Planet for the First Time

Reference: “An infrared transient from a star engulfing a planet” by Kishalay De et al., 3 May 2023, Nature. DOI: 10.1038/s41586-023-05842-x

The study, titled “An infrared transient from a star engulfing a planet,” received funding from NASA, the National Science Foundation (NSF), and the Heising-Simons Foundation. Caltech’s ZTF is funded by the NSF and an international collaboration of partners. Further support comes from the Heising-Simons Foundation and Caltech. ZTF data are processed and archived by Caltech’s IPAC. NASA’s Near-Earth Object Observations program supports ZTF’s search for near-Earth objects.

Launched in 2009, the WISE spacecraft was placed into hibernation in 2011 after completing its primary mission. In September 2013, NASA reactivated the spacecraft with the primary goal of scanning for near-Earth objects, or NEOs, and the mission and spacecraft were renamed NEOWISE. The mission is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. NEOWISE is a project of JPL, managed by Caltech for NASA, and the University of Arizona and is supported by NASA’s Planetary Defense Coordination Office. Science data processing takes place at IPAC at Caltech.

Google Analytics and related cookies are utilized across the TrendMD network (widget, website, blog). Learn more Yes No

Frequently Asked Questions (FAQs) about Star Consuming Planet