Tag Archive : Space telescope


Spitzer Space Telescope retired

NASA decommissioned the Spitzer Space Telescope on Thursday (30th January 2020). The signals with the commands to decommission were sent to the telescope on Thursday by the Jet Propulsion Laboratory in Pasadena, California.

“We leave behind a powerful scientific and technological legacy,” said Spitzer project manager Joseph Hunt, who declared the telescope’s end at 5:34 p.m. EST (2234 GMT) after engineers confirmed that the spacecraft was placed in safe mode, ceasing all science operations. “Everyone who has worked on this mission should be extremely proud today. There are literally hundreds of people who contributed directly to Spitzer’s success, and thousands who used its scientific capabilities to explore the universe.”

Four years back, NASA decided to decommission the Spitzer. This was based on a review of the agency’s current missions by then, and the future missions. The researches which used the telescope will continue with the James Webb Space Telescope when it’s launched in March 2021. Spitzer was originally planned to be shut down in 2018, but it got an extension of two years because the James Webb got delayed.

Spitzer was launched on 2003 August. The telescope was originally named the Space Infrared Telescope facility and was renamed Spitzer Space Telescope after the astronomer Lyman Spitzer. It was his idea to operate telescopes above earth atmosphere in space. The Spitzer was used to make discoveries inside the solar system as well as close to the edge of the universe.

“Spitzer taught us how important infrared light is to understanding our universe, both in our cosmic neighborhood and as far away as the most distant galaxies. The advances we make across many areas in astrophysics in the future will be because of Spitzer’s extraordinary legacy,” Paul Hertz, NASA’s director of astrophysics, said in a statement.

Spitzer collected data about the interstellar dust and exoplanets. Some discoveries like the exoplanets were not originally intended goals. Spitzer was used to finding many Earth-sized exoplanets in the Trappist-1 star system making it the largest batch of Earth-like planets found around a single star. It also was the first to detect molecules in the atmosphere of an exoplanet. It also provided the first measurements of wind and temperature of an exoplanet atmosphere.

“When Spitzer was being designed, scientists had not yet found a single transiting exoplanet, and by the time Spitzer launched, we still knew about only a handful,” said Sean Carey, manager of the Spitzer Science Center at IPAC at the California Institute of Technology (Caltech) in Pasadena. “The fact that Spitzer became such a powerful exoplanet tool when that wasn’t something the original planners could have possibly prepared for, is really profound. And we generated some results that absolutely knocked our socks off”

The Spitzer was one of the four observatories of NASA. With the decommissioning of Spitzer and Compton Gamma Ray Observatory (decommissioned in 2000), only two more remain in operation. They are the Hubble Telescope and Chandra X-Ray Observatory.

Read more about Spitzer Space Telescope


NASA Kepler telescope detects a vampire star system

The Kepler telescope is designed to detect exoplanets by observing stars. When a planet passes in front of a star the light from the star gets dimmed because of the obstruction caused by the planet. This method can be used to detect astronomical objects other than the exoplanets too. Objects which brighten or dim can be studied to identify astronomical objects which pass the stars. A new search in Kepler’s archived data has revealed an unusual brightening of a dwarf nova. It brightened 1600 times in less than a day and slowly faded back.

Scientists say that the star system may consist of a white dwarf star and a brown dwarf companion about one tenth the mass of white dwarf.

A white dwarf, also called a degenerate dwarf, is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to that of the Sun, while its volume is comparable to that of Earth. (Source: Wikipedia)

A brown dwarf is a type of sub-stellar object occupying the mass range between the heaviest gas giant planets and the lightest stars, having a mass between approximately 13 and 75–80 times that of Jupiter or approximately 2.5×1028 kg to about 1.5×1029 kg. Below this range are the sub-brown dwarfs (sometimes referred to as rogue planets), and above it are the lightest red dwarfs. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth.Unlike the stars in the main sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen (1H) to helium in their cores. (Source: Wikipedia)

The brown dwarf orbits the white dwarf every 83 minutes and the distance between stars is about 250000 miles. That distance is nearly the distance between earth and moon. The white dwarfs strong gravity pulls material from brown dwarf like a vampire sucking blood from its victim. The material stripped from the brown dwarf forms a disk around the white dwarf.

It was a very rare chance that Kepler was pointed in the right direction when the system had a super outburst more than 1000 times brighter. Kepler’s rapid observations take data every 30 minutes. This data was very important to catch the details of this outburst.

The data was hidden in Kepler’s data archive until it was identified by Ryan Ridden Harper and his team of the Space Telescope Science Institute (STScl), Baltimore, Maryland and the Australian National University in Canberra, Australia.”In a sense, we discovered this system accidentally. We weren’t specifically looking for a super-outburst. We were looking for any sort of transient,” said Ridden-Harper.

Kepler recorded the entire event observing a slow rise in brightness followed by a rapid intensification. The sudden brightness can be explained by theories. But the cause of the slow start remains a mystery. Standard physics theories do not explain this phenomenon. This phenomenon has been observed in two other dwarf nova outbursts also.

“These dwarf nova systems have been studied for decades, so spotting something new is pretty tricky,” said Ridden-Harper. “We see accretion disks all over—from newly forming stars to supermassive black holes—so it’s important to understand them.”

Some theories suggest that a super outburst is triggered when the accretion disk reaches a tipping point. As it gathers material, it grows in size until the outer edge experiences gravitational resonance with the orbiting brown dwarf. As a result, the disk might get super heated due to the thermal instability triggered. Observations show that the temperatures rise from 5000 Fahrenheit to 10000 Fahrenheit in its normal state and 17000 to 21000 Fahrenheit at the peak state of the super outburst.

These types of dwarf nova systems are very rare. Only about 100 are known yet. The time between outbursts may be years or decades. So it’s a challenge to observe one.

“The detection of this object raises hopes for detecting even more rare events hidden in Kepler data,” said co-author Armin Rest of STScI.

Team expect to continue analyzing data of Kepler and data from another exoplanet hunter, Transiting Exoplanet Survey Satellite (TESS) mission to search if there were such undetected incidents.

“The continuous observations by Kepler/K2, and now TESS, of these dynamic stellar systems allows us to study the earliest hours of the outburst, a time domain that is nearly impossible to reach from ground-based observatories,” said Peter Garnavich of the University of Notre Dame in Indiana.

The work was published on 21st October 2019 in the Royal Astronomical Society.

Source : Royal Astronomical Society