This figure from the study shows how the cosmic shoreline divides exoplanets that retain their atmospheres from exoplanets that lose their atmospheres via XUV radiation from their stars. Several of the planets in this study are clustered right near the shoreline, making them ‘keystone planets’ and a juicy target for further study. Credit: Mistry et al. 2023
NASA’s Kepler spacecraft has discovered most of the confirmed exoplanets that we know of. But its successor, TESS (Transiting Exoplanet Survey Satellite), is catching up. New research announces the validation of eight more TESS candidates, and they’re all Super-Earths.
TESS’s planet-hunting mission has a more refined goal than its predecessor, Kepler. TESS was specifically built to detect exoplanets transiting in front of bright stars in Earth’s neighborhood. It’s found about 400 confirmed exoplanets, but there’s a list of exoplanets awaiting confirmation that contains almost 6,000 candidates. There are only two ways to confirm all these exoplanets-in-waiting: further observations and statistical methods.
What all those unconfirmed candidates amount to is data. They’re hiding in TESS’s data, waiting for clever scientists to validate them. Further observations can help uncover them, but not alone.
The Validation of Transiting Exoplanets using Statistical Tools (VaTEST) project uses statistical tools and machine learning to comb through all of TESS’s data, looking for elusive exoplanets. In the VaTEST project, scientists are not only able to confirm planets while working around false positives; they’re also able to characterize exoplanet atmospheres suitable for further study.
A team of scientists presented their results in a paper titled “VaTEST III: Validation of 8 Potential Super-Earths from TESS Data.” Their paper is under review at the Publications of the Astronomical Society of Australia and is currently available on the preprint server arXiv. The lead author is Priyashkumar Mistry, a Ph.D. student at the University of New South Wales, Australia.
False positives are a persistent problem in exoplanet science. When you think about it, it’s easy to see why. TESS is looking for tiny dips in starlight around distant stars caused by an exoplanet passing in front of the stars. One blip isn’t enough; we need several, and there has to be a rhythm to them. But other things can give false impressions of a transiting planet, for example, eclipsing binary stars. Even a star’s natural variability can cloud the signals.
So TESS has gathered an enormous amount of data that has to be worked through, sorting out false positives from real signals, and that’s what VaTEST does. In this paper, the team has validated eight more Super-Earths.
“We have validated eight potential super-Earths using a combination of ground-based telescope data, high-resolution imaging, and the statistical validation tool known as TRICERATOPS,” the authors write.
Not only did they find eight more super-Earths, but they’ve identified six of them that are excellent candidates for additional study. “Among all these validated planets, six of them fall within the region known as’ keystone planets,’ which makes them particularly interesting for study,” they explain.
A keystone planet is an idea that has its roots in biology. In biology, a keystone species is one that defines an entire ecosystem. A great example is coral in coral reefs. Coral reefs are a distinct ecosystem anchored by coral.
In exoplanet science, a keystone planet is a planet that helps explain the overall population of exoplanets. In particular, it helps explain the radius gap we see in exoplanet populations. There’s a scarcity of planets between 1.5 and 2 Earth radii. It’s probably caused by photoevaporation mass loss. A star’s powerful radiation, especially in X-ray and UV emissions (XUV), can strip away a planet’s atmosphere over time, possibly creating a dearth of 1.5 to 2 Earth radii planets.
“It is noteworthy that planets within the size range investigated herein are absent from our own solar system, making their study crucial for gaining insights into the evolutionary stages between Earth and Neptune,” the authors explain. “These keystone planets play a pivotal role in advancing our understanding of the radius-valley phenomenon around low-mass stars.”
There’s another concept that relates to super-Earths and the radius gap, and it focuses on why some planets lose their atmospheres and fall below the gap and why others don’t. It’s called the “cosmic shoreline,” and it’s a statistical trend that links exoplanets together.
The cosmic shoreline is a dividing line between planets that have retained their atmospheres and planets that have lost them due to XUV radiation from their stars.
“In this study, we validate eight exoplanets using TESS, ground-based transit photometry, high-resolution imaging, and a statistical validation tool,” the authors explain. The researchers say that more precise mass measurements are needed to understand them better and that for three of the planets, these more precise measurements may be attainable.
Not only are some of these planets in the radius gap, but two of them are suitable for further atmospheric study with the JWST and its powerful instruments. “We also found that two of our validated planets, TOI-771b and TOI-4559b, are amenable for transmission spectroscopy using JWST,” the authors write.
When the JWST was being designed and built, scientists hoped that it would be able to scrutinize the atmospheres of Super-Earths. There are none of these worlds in our own solar system, so deciphering their atmospheres can help us understand where super-Earths fit into the exoplanet population, how they evolve, and how they relate to the radius gap and the cosmic shoreline.
The team simulated the atmospheres of the eight super-Earths and also what the JWST will likely see when it examines the atmospheres. The results are intriguing, showing signs of carbon dioxide, water, and, most intriguingly, methane. Methane can be a biosignature, though there’s a lot of uncertainty. Finding it in any exoplanet atmosphere will help scientists understand its presence more fully, whether it’s an actual biosignature or not.
“However, real observations of the validated planets using the JWST are required to confirm our transmission spectra analysis,” the paper concludes.
More information:
Priyashkumar Mistry et al, VaTEST III: Validation of 8 Potential Super-Earths from TESS Data, arXiv (2023). DOI: 10.48550/arxiv.2311.00688
Citation:
TESS finds eight more super-Earths (2023, November 6)
retrieved 7 November 2023
from https://phys.org/news/2023-11-tess-super-earths.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
