It’s no secret that the study of extrasolar planets has exploded since the turn of the century. Whereas astronomers knew less than a dozen exoplanets twenty years ago, thousands of candidates are available for study today. In fact, as of January 13th, 2023, a total of 5,241 planets have been confirmed in 3,916 star systems, with another 9,169 candidates awaiting confirmation. While opportunities for exoplanet research have grown exponentially, so too has the arduous task of sorting through the massive amounts of data involved.
Hence why astronomers, universities, research institutes, and space agencies have come to rely on citizen scientists in recent years. With the help of online resources, data-sharing, and networking, skilled amateurs can lend their time, energy, and resources to the hunt for planets beyond our Solar System. In recognition of their importance, NASA has launched Exoplanet Watch, a citizen science project sponsored by NASA’s Universe of Learning. This project lets regular people learn about exoplanets and get involved in the discovery and characterization process.
The Robert C. Byrd Green Bank Telescope (GBT), part of the Green Bank Observatory in West Virginia, is the world’s premiere single-dish radio telescope. Between its 100-meter dish (328-foot), unblocked aperture, and excellent surface accuracy, the GBT provides unprecedented sensitivity in the millimeter to meter wavelengths – very high to extremely high frequency (VHF to EHF). Since 2017, it also became one of the main instruments used by Breakthrough Listen and other institutes engaged in the Search for Extraterrestrial Intelligence (SETI).
Recently, an international team of researchers from the SETI Institute, Breakthrough Listen, and multiple universities scanned twelve exoplanets for signs of technological activity (aka. “technosignatures”). Their observations were timed to coincide with the planets passing in front of their sun relative to the observer (i.e., making a transit). While the survey did not detect any definitive evidence of technosignatures, they did identify two radio signals of interest that warrant follow-up observation. This new technique could vastly expand the field of SETI and create all kinds of opportunities for future research.
Exoplanets have become quite the sensation over the last decade-plus, with scientists confirming new exoplanets on a regular basis thanks to NASA’s Kepler and TESS missions, along with the James Webb Space Telescope recently examining exoplanet atmospheres, as well. It’s because of these discoveries that exoplanet science has turned into an exciting field of intrigue and wonder, but do the very same scientists who study these wonderful and mysterious worlds have their own favorite exoplanets? As it turns out, four such exoplanet scientists, sometimes referred to as “exoplaneteers”, were kind enough to share their favorites with Universe Today!
In April 2018, NASA launched the Transiting Exoplanet Survey Satellite(TESS), the successor to theKepler Space Telescope that revolutionized the exoplanet studies field. Like its predecessor, TESS has been scanning almost the entire sky for five years for extrasolar planets using the Transit Method. This consists of monitoring thousands of stars for periodic dips in brightness, which may indicate a planet passing in front of the star relative to the observer. To date, TESS has made 243 confirmed discoveries, with another 4562 candidates – or TESS Objects of Interest (TOI) – awaiting confirmation.
On Monday, October 10th, fans of the TESS mission and the research it conducts got a bit of a scare as the observatory experienced a malfunction and had to be put into safe mode. Three days later, at around 06:30 PM EDT (03:30 PM PDT) on October 13th, NASA announced that their engineers had successfully powered up the instrument and brought it back online. While technicians at NASA are still investigating the cause of the malfunction, the spacecraft is now back in its fine-pointing mode and has resumed its second extended mission (EM2).
The field of extrasolar planet studies continues to grow by leaps and bounds. Currently, 5,090 exoplanets have been confirmed in 3,816 systems, and another 8,933 candidates are awaiting confirmation. The majority of these have been Neptune-like gas giants (1,779), gas giants comparable to Jupiter or Saturn (1,536), and rocky planets many times the size of Earth (1,582). The most effective means for finding exoplanets has been the Transit Method (aka. Transit Photometry), where periodic dips in a star’s brightness are seen as an indication of a planet passing in front of its star (transiting) relative to the observer.
Using data from NASA’s Transiting Exoplanet Survey Satellite (TESS), an international team of astronomers has discovered a three-planet system orbiting a Sun-like star (HD 22946, or TOI 11) located about 205.5 light-years. Based on size estimates yielded from their transits, the team theorizes that these exoplanets consist of a rocky planet several times the size of Earth (a Super-Earth) and two gas giants smaller than Neptune. Given its proximity, this system could be ideal for follow-up studies and characterization with the James Webb Space Telescope (JWST).
When it comes to astronomy, the more instruments watching the sky, the better. Which is why it has been so frustrating that the world’s rising superpower – China – has long lacked focus on space-science missions. In recent years, with some notable exceptions, China’s space agency has focused on lunar exploration and human spaceflight, as well as some remote monitoring capabilities, leaving the technical know-how of arguably the world’s second more capable country on the sidelines when it comes to collecting space science data. Now, a team led by Jian Ge of the Shanghai Astronomical Observatory has suggested the most ambitious Chinese-led space science mission to date. And it plans to search for one of the holy grails of current astronomy research – an exoplanet like Earth.
The search for technosignatures has always taken a back seat in the broad search for extraterrestrial life forms. Biosignatures, such as methane in an exoplanet’s atmosphere, have long been front and center. But while we are searching for signs of biology, signs of technology might be hiding in plain sight. According to a new report from the members of the TechnoClimes conference, humanity could potentially find signs of technology by simply using data that will already be collected for other purposes. To prove their point, they came up with a list of possible technosignatures and cross-referenced them with a list of observatories that could potentially find them. The result is a framework of how to best search for technosignatures and a plethora of references for those seeking them out.
Remember that iconic scene in Star Wars, where a young Skywalker steps out onto the surface of Tatooine and watches the setting of two suns? As it turns out, this may be what it is like for lifeforms on the exoplanet known as Kepler-16, a rocky planet that orbits in a binary star system. Originally discovered by NASA’s Kepler mission, an international team of astronomers recently confirmed that this planet orbits two stars at once – what is known as a circumbinary planet.
The study of extrasolar planets has revealed some interesting things in recent decades. Not only have astronomers discovered entirely new types of planets – Super Jupiters, Hot Jupiters, Super-Earths, Mini-Neptunes, etc. – it has also revealed new things about solar system architecture and planetary dynamics. For example, astronomers have seen multiple systems of planets where the orbits of the planets did not conform to our Solar System.
According to a new study led by the University of Bern, an international team of researchers recently observed a Mini-Neptune (TOI-2257 b) orbiting a red dwarf star located about 188.5 light-years from Earth. What was interesting about this find was how the small ice giant had such an eccentric orbit, which is almost twice as long as it is wide! This is almost two and a half times as eccentric as Mercury, making TOI-2257 b the most eccentric planet ever discovered!
Looking to the future, astronomers are excited to see how machine learning – aka. deep learning and artificial intelligence (AI) – will enhance surveys. One field that is already benefitting in the search for extrasolar planets, where researchers rely on machine-learning algorithms to distinguish between faint signals and background noise. As this field continues to transition from discovery to characterization, the role of machine intelligence is likely to become even more critical.
Take the KeplerSpace Telescope, which accounted for 2879 confirmed discoveries (out of the 4,575 exoplanets discovered made to date) during its nearly ten years of service. After examining the data collected by Kepler using a new deep-learning neural network called ExoMiner, a research team at NASA’s Ames Research Center was able to detect 301 more planetary signals and add them to the growing census of exoplanets.