The Webb Telescope’s cool view of how stars and planets form


Simulated MIRI spectrum of a protoplanetary disk as it may appear in a number of Cycle 1 science programs. The spectrum shows many features that indicate the presence of water, methane, and many other chemicals. Photo credit: NASA, STScI.

The continued success of the multi-instrument optics alignment for the near-infrared instruments on NASA’s Webb Telescope drew the attention of the commissioning team Relax while we carefully monitor the cooling of the Mid-Infrared Instrument (MIRI) to its final operating temperature of less than 7 Kelvin (-447 degrees Fahrenheit or -266 degrees Celsius). During this slow cooldown, we continue other activities, including monitoring the near-infrared instruments. As MIRI cools, other major components of the observatory, such as the rear wall and mirrors, continue to cool and approach their operating temperatures.

Last week, the Webb team performed a stationary engine burn to maintain Webb’s position in orbit around the second Lagrange point. This was the second burn since Webb’s arrival on its last orbit in January; These burns will continue periodically throughout the life of the mission.

Over the past few weeks, we’ve shared some of the scientific discoveries Webb has anticipated, beginning with the study of the first stars and galaxies in the early Universe. Today we’ll see Webb peering within our own Milky Way at places where stars and planets are forming. Klaus Pontoppidan, Space Telescope Science Institute project scientist for Webb, shares the Cool Science planned for star and planet formation with Webb:

“We expect that in the first year of scientific operation, Webb will write entirely new chapters in the history of our origins – the formation of stars and planets. It is the study of star and planet formation with Webb that allows us to connect observations of mature exoplanets to their natal environments and our solar system to its own origins. Webb’s infrared capabilities are ideal for revealing how stars are, for three reasons and planets form: Infrared light is great at seeing through opaque dust, it picks up the thermal signatures of young stars and planets, and it reveals the presence of important chemical compounds like water and organic chemistry,” said Klaus Pontoppidan, Webb project scientist, Space Telescope Science Institute, Baltimore, Maryland.

“Let’s take a closer look at each reason. We often hear infrared light penetrating through obscuring dust, revealing newborn stars and planets still embedded in their parent clouds. Indeed, as seen by MIRI, mid-infrared light can go through clouds 20 times thicker than visible light. Since young stars are formed rapidly (at least by cosmic standards) – in just a few 100,000 years – their natal clouds did not have time to to resolve what’s obscuring what’s going on inside critical stage visible view Webb’s infrared sensitivity allows us to understand what’s happening in those very first stages, when gas and dust are actively collapsing to form new stars.

“The second reason has to do with the young stars and giant planets themselves. Both begin life as large, bloated structures that contract over time. While young stars tend to get hotter as they mature and giant planets cool, both typically emit more light in the infrared than visible wavelengths. This means Webb is excellent at discovering new young stars and planets and can help us understand the physics of their earliest formation. Earlier infrared observatories like the Spitzer Space Telescope used similar techniques for the nearest star forming cluster, but Webb will be discovering new young stars throughout the galaxy, the Magellanic Clouds and beyond.

“Finally, the infrared range (sometimes called ‘molecular fingerprinting range’) is ideal for identifying the presence of a range of chemicals, particularly water and various organics. All four of Webb’s science instruments can use their spectroscopic modes to detect a variety of important molecules. They are particularly sensitive to molecular ice, which is present in cold molecular clouds before stars are formed, and NIRCam and NIRSpec will for the first time comprehensively map the spatial distribution of ice to help us understand their chemistry. MIRI will also observe warm molecular gas near many young stars where rocky, potentially habitable planets may be forming. These observations will be sensitive to most bulk molecules and allow us to develop a chemical count at the earliest stages of planet formation. It’s no surprise that a significant amount of Webb’s early scientific investigations aim to measure how planetary systems make up the molecules that might be important to the origin of life as we know it.

“We will be watching MIRI closely as it cools. As the only mid-infrared instrument on Webb, MIRI will be particularly important in understanding the origins of stars and planets.”

The James Webb Space Telescope is the world’s largest, most powerful, and most complex space telescope ever built.

Video: Science with Webb: The Close Cosmos

Provided by NASA’s Goddard Space Flight Center

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