Iran’s space program reportedly launched its second monkey into space on a 15-minute flight on Saturday (Dec. 14).
Reports from the Islamic Republic News Agency said the ballistic flight reached as high as 75 miles (120 kilometers). That’s just beyond the Karman line of 62 miles (100 kilometers) that many authorities cite as the boundary of space.
“The President said that thank God, Iranian astronauts launched into the space the second monkey, Fargam, on the first day of the Week of Research, the ‘Pajouhesh’ explorer and landed in full safety and health,” read a dispatch on IRNA, which is the official state agency in Iran.
The United States, Soviet Union and France sent primates themselves into space in the 1960s, many of which did not survive the trip. “Ham” is among the most famous monkey space voyagers; the U.S. chimp launched into space and landed safely on Jan. 31, 1961, a few months before astronaut Al Shepard became the first American person in space that May.
Artist's conception of the SWIFT satellite in the act of capturing a gamma-ray burst. Credit: NASA
Supermassive black holes likely are behind most of the nearly 100,000 new X-ray sources plotted by the Swift X-ray Telescope, according to findings led by the University of Leicester in the United Kingdom. The results came from poring over eight years of data produced by the Swift space observatory.
“Stars and galaxies emit X-rays because the electrons in them move at extremely high speeds, either because they are very hot (over a million degrees) or because extreme magnetic fields accelerate them. The underlying cause is usually gravity; gas can be compressed and heated as it falls on to black holes, neutron stars and white dwarfs or when trapped in the turbulent magnetic fields of stars like our Sun,” the university stated.
“Most of the newly discovered X-ray sources are expected to signal the presence of super-massive black holes in the centers of large galaxies many millions of light-years from earth, but the catalog also contains transient objects (short-lived bursts of X-ray emission) which may come from stellar flares or supernovae.”
Plot points across the sky showing the new X-ray sources that the SWIFT satellite found. Blue represents higher-energy sources, and red lower-energy ones. The line represents the galactic plane, where many of the sources are concentrated. Source: Evans (University of Leicester)
Yutu rover emblazoned with Chinese Flag as seen by the Chang'e 3 lander on the moon on Dec. 15, 2013. Credit: China Space
Yutu rover emblazoned with Chinese Flag as seen by the Chang’e-3 lander on the moon on Dec. 15, 2013. Notice the rover tire tracks left behind in the loose lunar topsoil. Credit: China Space Story updated[/caption]
China’s ambitious lunar space exploration program achieved another stunning success Sunday night, Dec 15, when the countries inaugural Chang’e-3 lunar lander and rover beamed back portraits of one another snapped from the Moon’s surface – that also proudly displayed the brilliant red Chinese national flag shining atop an extraterrestrial body for the very first time in human history.
“I announce the complete success of the Chang’e-3 mission,” said Ma Xingrui, chief commander of China’s lunar program, during a live CCTV broadcast as the portraits were shown to a worldwide audience from huge screens mounted at the mission control at the Beijing Aerospace Control Center (BACC) in Beijing.
Chinese President Xi Jinping was on hand to personally witness the momentous events in real time.
A wave of cheers and high fives rocked around mission control as the startling imagery of the ‘Yutu’ rover and Chang’e-3 lander nestled atop the Moon’s soil in the Bay of Rainbows was received around 11:42 p.m. Sunday, local Beijing time, 10:42 a.m. EST, via China’s own deep space tracking network.
Xi Jinping’s presence was a clear demonstration of China’s confidence in its lunar team and the importance of this space spectacular to China’s prestige and technological prowess.
China thus became only the 3rd country in the world to successfully soft land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.
China’s ‘Yutu’ rover had just rolled majestically onto the Moon’s soil hours earlier on Sunday, Dec. 15, at 4:35 a.m. Beijing local time – barely seven hours after the Chang’e-3 mothership touched down atop the lava filled plains of the Bay of Rainbows on Dec. 14.
The rover’s wheels left behind noticeable tire tracks as it drove across the loose lunar topsoil.
Read my earlier detailed accounts of the Dec. 15 drive by Yutu onto the lunar surface illustrated with an extensive photo gallery – here; and of the stunning Dec. 14 landing – here.
CCTV showed China’s President gleefully shaking hands and extending congratulations with many members of the mission team at BACC after seeing the high resolution photos of the Chang’e-3 rover emblazoned with China’s flag for himself.
Chang’e 3 lander as seen by the rover Yutu on the moon on Dec. 15, 2013. Credit: China Space
It’s been nearly four decades since the prior lunar landing was accomplished by the Soviet Union’s Luna 24 sample return spacecraft back in 1976.
America’s last visit to the Moon’s surface occurred with the manned Apollo 17 landing mission – crewed by astronauts Gene Cernan and Harrison ‘Jack’ Schmitt , who coincidentally ascended from the lunar soil on Dec. 14, 1972 – exactly 41 years ago.
“The Central Committee of the Communist Party and the Central Military Commission [responsible for China’s space program] sends congratulations to all the staff that participated in the successful completion of the mission and China’s first soft landing on the moon,” said the Chinese vice premier Ma Kai during the CCTV broadcast.
“The rover and lander are working properly and reaching the goals set.”
“Chang’e-3 is China’s most complicated space mission,” said Kai. “This shows China is dedicated to the peaceful uses of space.”
“There are many more complicated and difficult tasks ahead.”
Chang’e-3 lander imaged by the rover Yutu on the moon on Dec. 15, 2013. Note landing ramp at bottom. Credit: CCTV
Indeed so far the Chang’e-3 mission has been primarily a highly successful demonstration of the extremely challenging engineering required to accomplish China’s first lunar landing.
Now the science phase can truly begin.
Over 4600 images have already been transmitted by Chang’e-3 since the Dec. 14 touchdown.
After rolling all six wheels into the dirt, Yutu – which translates as Jade Rabbit – drove to a location about nine meters north of the lander, according to CCTV commentators.
The rover then turned around so that the red Chinese flag emblazoned on the front side would be facing the lander’s high resolution color cameras for the eagerly awaited portraits of one another.
Yutu is nearly the size of a golf cart. It measures about 1.5 m x 1 m on its sides and stands about 1.5 m (nearly 5 feet) tall – nearly human height.
The 120 kg Yutu rover will now begin driving in a circle around the right side of the 1200 kg Chang’e-3 lander – for better illumination – at a distance ranging from 10 to 18 meters.
The rover will snap further photos of the lander as it traverses about from 5 specific locations – showing the front, side and back – over the course of the next 24 hours.
See the accompanying graphic – written in Chinese. Yutu and the Chang’e 3 lander are scheduled to take photos of each other soon from locations outlined in this artists concept. Credit: China Space
Thereafter Yutu will depart the landing site forever and begin its own lunar trek that’s expected to last at least 3 months.
So the rover and lander will soon be operating independently.
They are equipped with eight science instruments including multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.
The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail, according to Ouyang Ziyuan, senior advisor of China’s lunar probe project, in an interview on CCTV.
A UV camera will study the earth and its interaction with solar wind and a telescope will study celestial objects. This is done during the lunar day.
It will also investigate the moon’s natural resources for use by potential future Chinese astronauts.
China’s first lunar rover separates from Chang’e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: CCTV
The two probes are now almost fully operational. Most of the science instruments are working including at least three cameras and the ground penetrating radar.
And although they have survived the harsh lunar environment thus far, they still face massive challenges. They must prove that they can survive the extremely cold lunar night and temperature fluctuations of more than 300 degrees Celsius – a great engineering challenge.
The rover will hibernate during the two week long lunar night.
A radioisotopic heater will provide heat to safeguard the rovers computer and electronics – including the alpha particle X-ray instrument on the rover’s robotic arm.
The Bay of Rainbows, or Sinus Iridum region, is located in the upper left portion of the moon as seen from Earth. You can see the landing site with your own eyes.
Chang’e 3 targeted lunar landing site in the Bay of Rainbows or Sinus Iridum
It was imaged in high resolution by China’s prior lunar mission – the Chang’e-2 lunar orbiter and is shown in graphics herein.
China’s Chang’e-3 probe joins NASA’s newly arrived LADEE lunar probe which entered lunar orbit on Oct. 6 following a spectacular night time blastoff from NASA’s Wallops Flight Facility in Virginia.
Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.
China’s first lunar rover separates from Chang’e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: Xinhua/post processing by Marco Di Lorenzo/Ken Kremer
China's first lunar rover separates from Chang'e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: Xinhua/post processing by Marco Di Lorenzo/Ken Kremer
China’s first lunar rover separates from Chang’e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: Xinhua/post processing by Marco Di Lorenzo/Ken Kremer Updated- See below Photo Gallery of Yutu’s descent to lunar surface on Dec. 15, 2013[/caption]
China’s first ever lunar rover rolled majestically onto the Moon’s soil on Sunday, Dec. 15, barely seven hours after the Chang’e-3 mothership touched down atop the lava filled plains of the Bay of Rainbows.
Check out the gallery of stunning photos and videos herein from China’s newest space spectacular atop stark lunar terrain.
The six wheeled ‘Yutu’, or Jade Rabbit, rover drove straight off a pair of ramps at 4:35 a.m. Beijing local time and sped right into the history books as it left a noticeably deep pair of tire tracks behind in the loose lunar dirt.
China’s first lunar rover separates from Chang’e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: CCTV
The stunning feat was broadcast on China’s state run CCTV using images transmitted to Earth from cameras mounted on the Chang’e-3 lander and aimed directly at the rear of the departing moon buggy.
Watch this YouTube video from CCTV showing the separation of ‘Yutu’ from the lander:
The scene was reminiscent of NASA’s Mars Sojourner rover driving of the Mars Pathfinder lander back in 1997.
Chinese space engineers based at the Beijing Aerospace Control Center (BACC) carefully extended a pair of ramps out from the lander in a complex process, drove Yutu onto the ramps and then gently lowered them onto the moon’s soil.
China’s Change’-3 mission had just safely soft landed on the Moon hours only earlier on Saturday, Dec. 14 at 9:11 p.m. Beijing time, 8:11 EST at the Sinus Iridum region, or Bay of Rainbows.
China thus became only the 3rd country in the world to successfully land a spacecraft on Earth’s nearest neighbor after the United States and the Soviet Union.
A video grab shows China’s first moon rover, Yutu, or Jade Rabbit, separating from Chang’e-3 moon lander early Dec. 15, 2013. The six-wheeled rover separated from the lander early on Sunday, several hours after the Chang’e-3 probe soft-landed on the lunar surface. Credit: Xinhua
It’s been nearly four decades since the prior lunar landing was accomplished by the Soviet Union’s Luna 24 sample return spacecraft.
Read my detailed account of the Chang’e-3 landing on Dec. 14 – here.
1st post landing image transmitted from the Moon’s surface by China’s Chang’e-3 lunar lander on Dec. 14, 2013. Credit: CCTV/post processing by Marco Di Lorenzo/Ken Kremer
Watch this YouTube video compilation of CCTV’s Dec. 14 landing coverage:
Over 4600 images have already been transmitted by Chang’e-3 in less than a day on the Moon.
Tomorrow, the 120 kg Yutu rover will begin driving in a circle around the 1200 kg lander.
And the pair of lunar explorers will snap eagerly awaited portraits of one another!
The rover and lander are equipped with 8 science instruments multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.
The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail, according to Ouyang Ziyuan, senior advisor of China’s lunar probe project, in an interview on CCTV.
China’s Chang’e-3 probe joins NASA’s newly arrived LADEE lunar probe which entered lunar orbit on Oct. 6 following a spectacular night time blastoff from NASA’s Wallops Flight Facility in Virginia.
Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.
Yutu moves towards drive off ramp still atop the Chang’e-3 lander, shown in this screen shot from early Dec. 15, 2013. Credit: CCTVYutu atop the transfer ramp to lunar surface. Credit: CCTVYutu descends down the transfer ramp to lunar surface. Credit: CCTVImage shows the trajectory of the lunar probe Chang’e-3 approaching the landing site on Dec. 14.China’s first lunar rover separates from Chang’e-3 moon lander early Dec. 15, 2013. Screenshot taken from the screen of the Beijing Aerospace Control Center in Beijing. Credit: Xinhua
Christopher Nolan, the writer and director of Memento, Inception, and the most recent Batman films, is taking up space on the big screen next year — literally. Nolan’s newest film, Interstellar, will be a space exploration adventure featuring Matthew McConaughey, Jessica Chastain, Anne Hathaway, and Michael Caine (of course) and, based on this teaser trailer, maintains a reverent awareness of the iconic missions of the Space Age.
Photo taken on Dec. 14, 2013 shows a picture of the moon surface taken by the on-board camera of lunar probe Chang'e-3 on the screen of the Beijing Aerospace Control Center in Beijing. This marks the first time that China has sent a spacecraft to soft land on the surface of an extraterrestrial body. Credit: Xinhua/CCTV
Photo taken on Dec. 14, 2013 shows a picture of the moon surface taken by the on-board camera of lunar probe Chang’e-3 on the screen of the Beijing Aerospace Control Center in Beijing. This marks the first time that China has sent a spacecraft to soft land on the surface of an extraterrestrial body. Credit: Xinhua/CCTV Story updated[/caption]
China scored a stunning, history making success with the successful touchdown of the ambitious Chang’e-3 probe with the ‘Yutu’ rover on the surface of the Moon today, Dec. 14, on the country’s first ever attempt to conduct a landing on an extraterrestrial body.
The dramatic Chang’e-3 soft landing on the lava filled plains of the Bay of Rainbows occurred at about 8:11 am EST, 9:11 p.m. Beijing local time, 1311 GMT today.
The monumental feat is the first landing on the Moon by any entity in nearly four decades. It was broadcast live on CCTV, China’s state run television network.
Note: Read my related new story with a photo gallery of Yutu’s 6 wheels rolling onto lunar soil – here
This maiden Chinese moon landing marks a milestone achievement for China and clearly demonstrates the country’s technological prowess.
A tidal wave of high fives was unleashed by the huge teams of Chinese space engineers teams controlling the flight from the Beijing Aerospace Control Center (BACC).
There was also a huge sense of relief from the nail biting tension upon confirmation of the successful soft landing following many years of hard work and intense planning.
The Chang’e-3 mission entails the first soft landing on the Moon by anyone since the Soviet Union’s unmanned Luna 24 sample return vehicle touched down back in 1976.
Artists concept of the rocket assisted landing of China’s lunar probe Chang’e-3.
China now joins an elite club of three, including the United States, who have mastered the critical technology required to successfully touch down on Earth’s nearest neighbor.
China’s space vision also stands in total contrast to the utter lack of vision emanating from so called political leaders in Washington, DC who stymie NASA and US science at every opportunity!
‘Yutu’ could very well serve as a forerunner for testing the key technologies required for a Chinese manned lunar landing in the next decade.
In one of its first acts from the surface, the landers life giving solar panels were deployed as planned within minutes of touchdown
The Chang’e-3 mission is comprised of China’s ‘Yutu’ lunar lander riding piggyback atop a much larger four legged landing vehicle.
The Chang’e-3 lander transmitted its first images of the moon in real time during its approach to the lunar surface during the final stages of the ongoing landing operation carried live by CCTV.
A total of 59 images were received instead of the 10 expected, said a CCTV commentator.
The voyage from the Earth to the Moon began 12 days ago with the flawless launch of Chang’e-3 atop China’s Long March 3-B booster at 1:30 a.m. Beijing local time, Dec. 2, 2013 (12:30 p.m. EST, Dec. 1) from the Xichang Satellite Launch Center, in southwest China.
Chang’e-3 made a rocket powered descent to the Moon’s surface today by firing the landing thrusters starting at the altitude of 15 km (9 mi) for a soft landing targeted to a preselected area on the Bay of Rainbows.
The powered descent was autonomous and took about 12 minutes.
The variable thrust engine can continuously vary its thrust power between 1,500 to 7,500 newtons. It was the biggest ever used by China in space said a commentator on CCTV.
The variable thrust engine enabled Chang’e-3 to reduce its deceleration as it approached the moon.
The descent was preprogrammed and controlled by the probe itself, not from the ground.
A descent camera was mounted on the lander’s belly
The 1200 kg lander is equipped with unprecedented terrain recognition equipment and software to hover above the landing site and confirm it was safe. This enabled the craft to avoid rock and boulder fields that could spell catastrophe even in the final seconds before touchdown if the vehicle were to land directly on top of them.
The descent engine fired until the lander was about hovering 100 meters above the lunar surface.
After determining it was safe to proceed, the lander descended further to about 3 meters. The engine then cut off and the lander free fell the remaining distance. The impact was cushioned by shock absorbers.
The solar panels soon unfurled. They are the most efficient Chinese solar panels available, said a CCTV commentator.
The Bay of Rainbows, or Sinus Iridum region, is located in the upper left portion of the moon as seen from Earth. You can see the landing site with your own eyes.
It was imaged in high resolution by China’s prior lunar mission – the Chang’e-2 lunar orbiter – and is shown in graphics herein.
The Yutu rover is also unfurling its solar panels and mast today.
Yutu, which translates as Jade Rabbit, stands 150 centimeters high, or nearly 5 feet – human height.
It weighs approximately 120 kilograms and sports a robotic arm equipped with advanced science instruments.
On Sunday, the six-wheeled ‘Yutu’ rover with a rocker bogie suspension similar to NASA’s Mars rovers will be lowered in stages to the moon’s surface in a complex operation and then drive off a pair of landing ramps to explore the moon’s terrain for at least three months.
In what promises to be a space spectacular, the lander and rover are expected to photograph one another soon after Yutu rolls onto the Bay of Rainbows.
They will work independently.
The rover and lander are equipped with multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.
The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail, according to Ouyang Ziyuan, senior advisor of China’s lunar probe project, in an interview on CCTV.
The Chang’e-3 lander is powered by a combination of solar arrays and a nuclear battery said CCTV, in order to survive the two week long lunar nights.
Chinese space officials expect the lander will function a minimum of 1 year.
ESA’s network of tracking stations are providing crucial support to China for Chang’e-3 from launch to landing.
China’s Chang’e-3 probe joins NASA’s newly arrived LADEE lunar probe which entered lunar orbit on Oct. 6 following a spectacular night time blastoff from NASA’s Wallops Flight Facility in Virginia.
Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.
China's lunar probe Chang'e-3 is expected to land on Sinus Iridum (Bay of Rainbows) of the moon in mid-December 2013. Credit: Xinhua
All systems appear to be “GO” for the world’s first attempt to soft land a space probe on the Moon in nearly four decades.
China’s maiden moon landing probe – Chang’e-3 – is slated to attempt the history making landing this weekend on a lava plain in the Bay of Rainbows, or Sinus Iridum region.
Chinese space engineers at the Beijing Aerospace Control Center (BACC) paved the way for the historic touchdown by successfully commanding Chang’e-3 to descend from the 100 km-high lunar circular orbit it reached just one week ago on Dec. 6, to “an elliptical orbit with its nearest point about 15 km away from the moon’s surface”, according to a statement from China’s State Administration of Science, Technology and Industry for National Defense (SASTIND).
UPDATE: CCTV is providing live landing coverage
The first pictures taken from the alien lunar surface in some 37 years are expected to be transmitted within days or hours of touchdown planned as early as Saturday, Dec. 14, at 9:40 p.m. Beijing local time, 8:40 a.m. EST.
CCTV, China’s state run network, carried the launch live. It remains to be seen whether they will have live coverage of the landing since there have been no programming announcements.
SASTIND said the orbit lowering thruster firing was “conducted above the dark side of the moon at 9:20 p.m.” on Dec. 10, Beijing local time.
Confirmation of the Chang’e-3 probes new, lower orbit was received four minutes later.
China’s lunar probe Chang’e-3 entered an orbit closer to the moon on Dec. 10, 2013. Credit: Xinhua
If successful, the Chang’e-3 mission will mark the first soft landing on the Moon since the Soviet Union’s unmanned Luna 24 sample return vehicle landed back in 1976.
China would join an elite club of three, including the United States, who have mastered the critical technology to successfully touch down on Earth’s nearest neighbor.
The Chang’e-3 mission is comprised of China’s ‘Yutu’ lunar lander riding piggyback atop a much larger four legged landing probe.
Artists concept of the Chinese Chang’e-3 lander and rover on the lunar surface. Credit: Beijing Institute of Spacecraft System Engineering
The voyage from the Earth to the Moon began 12 days ago with the flawless launch of Chang’e-3 atop China’s Long March 3-B booster at 1:30 a.m. Beijing local time, Dec. 2, 2013 (12:30 p.m. EST, Dec. 1) from the Xichang Satellite Launch Center, in southwest China.
Chang’e-3 will make a powered descent to the Moon’s surface on Dec. 14 by firing the landing thrusters at the altitude of 15 km (9 mi) for a soft landing in a preselected area on the Bay of Rainbows.
The powered descent will take about 12 minutes.
The variable thrust engine can continuously vary its thrust power between 1,500 to 7,500 newtons, according to Xinhua.
The Bay of Rainbows is located in the upper left portion of the moon as seen from Earth. It was imaged in high resolution by China’s prior lunar mission – the Chang’e-2 lunar orbiter.
The 1200 kg lander is equipped with terrain recognition equipment and software to avoid rock and boulder fields that could spell catastrophe even in the final seconds before touchdown if the vehicle were to land directly on top of them.
Chang’e-3 is powered by a combination of solar arrays and a nuclear device in order to survive the two week long lunar nights.
The six-wheeled ‘Yutu’ rover, with a rocker bogie suspension, will be lowered in stages to the moon’s surface in a complex operation and then drive off a pair of landing ramps to explore the moon’s terrain.
Yutu measures 150 centimeters high and weighs approximately 120 kilograms and sports a robotic arm equipped with science instruments.
The rover and lander are equipped with multiple cameras, spectrometers, an optical telescope, ground penetrating radar and other sensors to investigate the lunar surface and composition.
The radar instrument installed at the bottom of the rover can penetrate 100 meters deep below the surface to study the Moon’s structure and composition in unprecedented detail.
China’s Chang’e-3 probe joins NASA’s newly arrived LADEE lunar probe which entered lunar orbit on Oct. 6 following a spectacular night time blastoff from NASA’s Wallops Flight Facility in Virginia.
Stay tuned here for Ken’s continuing Chang’e-3, LADEE, MAVEN, MOM, Mars rover and more news.
Artist's impression of a Y-dwarf, the coldest known type of brown dwarf star. (NASA/JPL-Caltech)
When it’s a brown dwarf — but where do we draw the line?
Often called “failed stars,” brown dwarfs are curious cosmic creatures. They’re kind of like swollen, super-dense Jupiters, containing huge amounts of matter yet not quite enough to begin fusing hydrogen in their cores. Still, there has to be some sort of specific tipping point, and astronomers (being the scientists that they are) would like to know: when does a brown dwarf stop and a star begin?
Researchers from Georgia State University now have the answer.
From a press release issued Dec. 9 from the National Optical Astronomy Observatory (NOAO):
For most of their lives, stars obey a relationship referred to as the main sequence, a relation between luminosity and temperature – which is also a relationship between luminosity and radius. Stars behave like balloons in the sense that adding material to the star causes its radius to increase: in a star the material is the element hydrogen, rather than air which is added to a balloon. Brown dwarfs, on the other hand, are described by different physical laws (referred to as electron degeneracy pressure) than stars and have the opposite behavior. The inner layers of a brown dwarf work much like a spring mattress: adding additional weight on them causes them to shrink. Therefore brown dwarfs actually decrease in size with increasing mass.
As Dr. Sergio Dieterich, the lead author, explained, “In order to distinguish stars from brown dwarfs we measured the light from each object thought to lie close to the stellar/brown dwarf boundary. We also carefully measured the distances to each object. We could then calculate their temperatures and radii using basic physical laws, and found the location of the smallest objects we observed (see the attached illustration, based on a figure in the publication). We see that radius decreases with decreasing temperature, as expected for stars, until we reach a temperature of about 2100K. There we see a gap with no objects, and then the radius starts to increase with decreasing temperature, as we expect for brown dwarfs. “
Dr. Todd Henry, another author, said: “We can now point to a temperature (2100K), radius (8.7% that of our Sun), and luminosity (1/8000 of the Sun) and say ‘the main sequence ends there’ and we can identify a particular star (with the designation 2MASS J0513-1403) as a representative of the smallest stars.”
The relation between size and temperature at the point where stars end and brown dwarfs begin (based on a figure from the publication) Image credit: P. Marenfeld & NOAO/AURA/NSF.
“We can now point to a temperature (2100K), radius (8.7% that of our Sun), and luminosity (1/8000 of the Sun) and say ‘the main sequence ends there’.”
Aside from answering a fundamental question in stellar astrophysics about the cool end of the main sequence, the discovery has significant implications in the search for life in the universe. Because brown dwarfs cool on a time scale of only millions of years, planets around brown dwarfs are poor candidates for habitability, whereas very low mass stars provide constant warmth and a low ultraviolet radiation environment for billions of years. Knowing the temperature where the stars end and the brown dwarfs begin should help astronomers decide which objects are candidates for hosting habitable planets.
The data came from the SOAR (SOuthern Astrophysical Research) 4.1-m telescope and the SMARTS (Small and Moderate Aperture Research Telescope System) 0.9-m telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile.
