TYB
Webb Confirms Its First Exoplanet
January 11, 2023
Researchers confirmed an exoplanet, a planet that orbits another star, using NASA’s James Webb Space Telescope for the first time. Formally classified as LHS 475 b, the planet is almost exactly the same size as our own, clocking in at 99% of Earth’s diameter. The research team is led by Kevin Stevenson and Jacob Lustig-Yaeger, both of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.
The team chose to observe this target with Webb after carefully reviewing targets of interest from NASA’s Transiting Exoplanet Survey Satellite (TESS), which hinted at the planet’s existence. Webb’s Near-Infrared Spectrograph (NIRSpec) captured the planet easily and clearly with only two transit observations.
“There is no question that the planet is there. Webb’s pristine data validate it,” said Lustig-Yaeger. “The fact that it is also a small, rocky planet is impressive for the observatory,” Stevenson added.
“These first observational results from an Earth-size, rocky planet open the door to many future possibilities for studying rocky planet atmospheres with Webb,” agreed Mark Clampin, Astrophysics Division director at NASA Headquarters in Washington. “Webb is bringing us closer and closer to a new understanding of Earth-like worlds outside our solar system, and the mission is only just getting started.”
Among all operating telescopes, only Webb is capable of characterizing the atmospheres of Earth-sized exoplanets. The team attempted to assess what is in the planet’s atmosphere by analyzing its transmission spectrum. Although the data shows that this is an Earth-sized terrestrial planet, they do not yet know if it has an atmosphere. “The observatory’s data are beautiful,” said Erin May, also of the Johns Hopkins University Applied Physics Laboratory. “The telescope is so sensitive that it can easily detect a range of molecules, but we can’t yet make any definitive conclusions about the planet’s atmosphere.”
Although the team can’t conclude what is present, they can definitely say what is not present. “There are some terrestrial-type atmospheres that we can rule out,” explained Lustig-Yaeger. “It can’t have a thick methane-dominated atmosphere, similar to that of Saturn’s moon Titan.”
The team also notes that while it’s possible the planet has no atmosphere, there are some atmospheric compositions that have not been ruled out, such as a pure carbon dioxide atmosphere. “Counterintuitively, a 100% carbon dioxide atmosphere is so much more compact that it becomes very challenging to detect,” said Lustig-Yaeger. Even more precise measurements are required for the team to distinguish a pure carbon dioxide atmosphere from no atmosphere at all. The researchers are scheduled to obtain additional spectra with upcoming observations this summer.
Webb also revealed that the planet is a few hundred degrees warmer than Earth, so if clouds are detected, it may lead the researchers to conclude that the planet is more like Venus, which has a carbon dioxide atmosphere and is perpetually shrouded in thick clouds. “We’re at the forefront of studying small, rocky exoplanets,” Lustig-Yaeger said. “We have barely begun scratching the surface of what their atmospheres might be like.”
The researchers also confirmed that the planet completes an orbit in just two days, information that was almost instantaneously revealed by Webb’s precise light curve. Although LHS 475 b is closer to its star than any planet in our solar system, its red dwarf star is less than half the temperature of the Sun, so the researchers project it still could have an atmosphere.
The researchers’ findings have opened the possibilities of pinpointing Earth-sized planets orbiting smaller red dwarf stars. “This rocky planet confirmation highlights the precision of the mission’s instruments,” Stevenson said. “And it is only the first of many discoveries that it will make.” Lustig-Yaeger agreed. “With this telescope, rocky exoplanets are the new frontier.”
LHS 475 b is relatively close, at only 41 light-years away, in the constellation Octans.
https://exoplanets.nasa.gov/news/1722/webb-confirms-its-first-exoplanet/
https://exoplanets.nasa.gov/news/1720/second-earth-sized-world-found-in-systems-habitable-zone/
Nice, thanks
Japan’s Prime Minister, US Secretary of State to Visit NASA
Jan 11, 2023
NASA Administrator Bill Nelson and Deputy Administrator Pam Melroy will welcome Japan’s Prime Minister Kishida Fumio, U.S. Secretary of State Antony J. Blinken, and other U.S. and Japanese leaders to NASA Headquarters in Washington at 4:30 p.m. EST Friday, Jan. 13.
The visit will air on NASA Television, NASA app, and the agency’s website, as well as flagship Twitter and YouTube channels.
Blinken and Japan’s Minister for Foreign Affairs Hayashi Yoshimasa are expected to sign an agreement at NASA that will build on the nations’ commitment to the peaceful, transparent exploration of space.
Japanese Ambassador to the U.S. Tomita Koji, Japan Aerospace Exploration Agency President (JAXA) Yamakawa Hiroshi, and U.S. Ambassador to Japan Rahm Emanuel, also will be in attendance.
The signing and visit come on the heels of a November 2022 agreement by NASA and the Government of Japan outlining further contributions by Japan to Gateway, a key component of the agency’s Artemis missions for long-term lunar exploration.
https://www.nasa.gov/press-release/japan-s-prime-minister-us-secretary-of-state-to-visit-nasa
Green comet tomorrow
Astronomers Dig Out Buried Black Holes with NASA's Chandra
Jan 11, 2023
Hundreds of black holes previously hidden, or buried, have been found using NASA’s Chandra X-ray Observatory. This result helps give astronomers a more accurate census of black holes in the universe.
The black holes in this new study are the supermassive variety that contain millions or even billions of times the mass of the Sun. While astronomers think that almost all large galaxies harbor giant black holes in their centers, only some of the black holes will be actively pulling in material that produces radiation, and some will be buried underneath dust and gas.
By combining data from the Chandra Source Catalog – a public repository including hundreds of thousands of X-ray sources detected by the observatory over its first 15 years – and optical data from the Sloan Digital Sky Survey (SDSS), a team of astronomers was able to identify hundreds of black holes that had previously been hidden. They are in galaxies not previously identified to contain quasars, extremely bright objects with rapidly growing supermassive black holes.
“Astronomers have already identified huge numbers of black holes, but many remain elusive,” said Dong-Woo Kim of the Center for Astrophysics | Harvard & Smithsonian (CfA), who led the study. “Our research has uncovered a missing population and helped us understand how they are behaving.”
For about 40 years scientists have known about galaxies that look normal in optical light – with light from stars and gas but not the distinctive optical signatures of a quasar – but shine brightly in X-rays. They refer to these objects as “X-ray bright optically normal galaxies” or “XBONGs.”
By systematically combing through the deep Chandra Source Catalog and comparing to SDSS optical data, the researchers identified 817 XBONG candidates, more than ten times the number known before Chandra was in operation. Chandra’s sharp images, matching the quality of those from SDSS, and the large amount of data in the Chandra Source Catalog made it possible to detect this many XBONG candidates. Further study revealed that about half of these XBONGs represent a population of previously hidden black holes.
“These results show how powerful it is to compare X-ray and optical data mines,” said co-author Amanda Malnati, an undergraduate student at Smith College in Northampton, Massachusetts. “The Chandra Source Catalog is a growing treasure that will help astronomers make discoveries for years to come.”
X-rays are particularly useful to search for rapidly growing black holes because material swirling around them is superheated to millions of degrees and glows strongly in X-ray wavelengths. A thick cocoon of gas and dust surrounding a black hole will block most or all the light at optical wavelengths. X-rays, however, pass through the cocoon much more easily to be detected by Chandra.
After studying the amount of X-rays detected at different energies for each source, the team concluded that about half the XBONG candidates involve X-ray sources that are buried under thick gas because relatively small amounts of low- energy X-rays were detected. Such X-rays are blocked more easily by layers of surrounding gas than higher- energy ones.
These X-ray sources are so bright that almost all of them must be from material surrounding rapidly growing supermassive black holes. Data from NASA's Wide-Field Infrared Survey Explorer provides additional evidence that about half of the XBONGs are buried, growing supermassive black holes. These black holes range in distances between 550 million and 7.8 billion light-years from Earth.
“It’s not every day that you can say you discovered a black hole,” said co-author Alyssa Cassity, a graduate student at the University of British Columbia, “so, it’s very exciting to realize that we have discovered hundreds of them.”
The explanation for the XBONGs that are not buried underneath thick gas is less clear. About 100 of the X-ray sources may not be single points of X-rays sources, but instead appear spread out. Some of these may be galaxies in previously unidentified groups or clusters of galaxies, which are known to contain large quantities of hot, X-ray emitting gas. No more than about 20% of the XBONGs can be categorized this way. The remaining 30% may contain some supermassive black holes located in galaxies where the optical signals from the supermassive black holes are diluted by relatively bright light from stars. Scientists will need additional research to sort out the true nature of these XBONGs.
https://www.nasa.gov/mission_pages/chandra/news/astronomers-dig-out-buried-black-holes-with-nasas-chandra.html