According to the most widely-accepted cosmological models, the first galaxies began to form between 13 and 14 billion years ago. Over the course of the next billion years, the cosmic structures we’ve all come to know emerged. These include things like galaxy clusters, superclusters, and filaments, but also galactic features like globular clusters, galactic bulges, and Supermassive Black Holes (SMBHs).
However, like living organisms, galaxies have continued to evolve ever since. In fact, over the course of their lifetimes, galaxies accrete and eject mass all the time. In a recent study, an international team of astronomers calculated the rate of inflow and outflow of material for the Milky Way. Then the good folks at astrobites gave it a good breakdown and showed just how relevant it is to our understanding of galactic formation and evolution.
Ever since the project was first conceived, scientists have been eagerly awaiting the day that the James Webb Space Telescope (JWST) will take to space. As the planned successor to Hubble, the JWST will use its powerful infrared imaging capabilities to study some of the most distant objects in the Universe (such as the formation of the first galaxies) and study extra-solar planets around nearby stars.
However, there has been a lot of speculation and talk about which targets will be the JWST’s first. Thankfully, following the recommendation of the Time Allocation Committee and a thorough technical review, the Space Telescope Science Institute (STScI) recently announced that it has selected thirteen science “early release” programs, which the JWST will spend its first five months in service studying.
As part of the JWST Director’s Discretionary Early Release Science Program (DD-ERS), these thirteen targets were chosen by a rigorous peer-review process. This consisted of 253 investigators from 18 counties and 106 scientific institutions choosing from over 100 proposals. Each program has been allocated 500 hours of observing time, once the 6-month commissioning period has ended.
As Ken Sembach, the director of the Space Telescope Science Institute (STScI), said in an ESA press statement:
“We were impressed by the high quality of the proposals received. These programmes will not only generate great science, but will also be a unique resource for demonstrating the investigative capabilities of this extraordinary observatory to the worldwide scientific community… We want the research community to be as scientifically productive as possible, as early as possible, which is why I am so pleased to be able to dedicate nearly 500 hours of director’s discretionary time to these early release science observations.”
The thirteen programs selected include “Through the looking GLASS“, which will rely on the astronomical community’s experience using Hubble to conduct slitless spectroscopy and previous surveys to gather data on galaxy formation and the intergalactic medium, from the earliest epochs of the Universe to the present day. The Principal Investigator (PI) for this program is Tommaso Treu of the University of California Los Angeles.
Another is the Cosmic Evolution Early Release Science (CEERS) program, which will conduct overlapping observations to create a coordinated extragalactic survey. This survey is intended to let astronomers see the first visible light of the Universe (ca. 240,000 to 300,000 years after the Big Bang), as well as information from the Reionization Epoch (ca. 150 million to 1 billion years after the Big Bang) and the period when the first galaxies formed. The PI for this program is Steven Finkelstein of the University of Texas at Austin.
However, compared to earlier missions, the JWST will be able to study transiting planets in unprecedented detail, which is anticipated to reveal volumes about their respective atmospheric compositions, structures and dynamics. This program, for which the PI is Imke de Pater from the University of California Berkeley, is therefore expected to revolutionize our understanding of planets, planet formation, and the origins of life.
Also focused on the study of exoplanets is the High Contrast Imaging of Exoplanets and Extraplanetary Systems program, which will focus on directly imaged planets and circumstellar debris disks. Once again, the goal is to use the JWST’s enhanced capabilities to provide detailed analyses on the atmospheric structure and compositions of exoplanets, as well as the cloud particle properties of debris disks.
But of course, not all the programs are dedicated to the study of things beyond our Solar System, as is demonstrated by the program that will focus on Jupiter and the Jovian System. Adding to the research performed by the Galileo and Juno missions, the JWST will use its suite of instruments to characterize and produce maps of Jupiter’s cloud layers, winds, composition, auroral activity, and temperature structure.
This program will also focus on some of Jupiter’s largest moons (aka. the “Galilean Moons”) and the planet’s ring structure. Data obtained by the JWST will be used to produce maps of Io’s atmosphere and volcanic surface, Ganymede’s tenuous atmosphere, provide constrains on these moons thermal and atmospheric structure, and search for plumes on their surfaces. As Alvaro Giménez, the ESA Director of Science, proclaimed:
“It is exciting to see the engagement of the astronomical community in designing and proposing what will be the first scientific programs for the James Webb Space Telescope. Webb will revolutionize our understanding of the Universe and the results that will come out from these early observations will mark the beginning of a thrilling new adventure in astronomy.”
During its mission, which will last for a minimum of five years (barring extensions), the JWST will also address many other key topics in modern astronomy, probing the Universe beyond the limits of what Hubble has been capable of seeing. It will also build on observations made by Hubble, examining galaxies whose light has been stretched into infrared wavelengths by the expansion of space.
Beyond looking farther back in time to chart cosmic evolution, Webb will also examine the Supermassive Black Holes (SMBH) that lie at the centers of most massive galaxies – for the purpose of obtaining accurate mass estimates. Last, but not least, Webbwill focus on the birth of new stars and their planets, initially focusing on Jupiter-sized worlds and then shifting focus to study smaller super-Earths.
John C. Mather, the Senior Project Scientist for the JWST and a Senior Astrophysicist at NASA’s Goddard Space Flight Center, also expressed enthusiasm for the selected programs. “I’m thrilled to see the list of astronomers’ most fascinating targets for the Webb telescope, and extremely eager to see the results,” he said. “We fully expect to be surprised by what we find.”
For years, astronomers and researchers have been eagerly awaiting the day when the JWST begins gathering and releasing its first observations. With so many possibilities and so much waiting to be discovered, the telescope’s deployment (which is scheduled for 2019) is an event that can’t come soon enough!
It’s been over a century since Einstein firs proposed his Theory of General Relativity, his groundbreaking proposal for how gravity worked on large scales throughout the cosmos. And yet, after all that time, experiments are still being conducted that show that Einstein’s field equations were right on the money. And in some cases, old experiments are finding new uses, helping astronomers to unlock other astronomical mysteries.
Case in point: using the Hubble Space Telescope, NASA astronomers have repeated a century-old test of General Relativity to determine the mass of a white dwarf star. In the past, this test was used to determine how it deflects light from a background star. In this case, it was used to provide new insights into theories about the structure and composition of the burned-out remnants of a star.
White dwarfs are what become of a star after it has exited the Main Sequence of its lifespan after exhausting their nuclear fuel. This is followed by the star expelling most of its outer material, usually through a massive explosion (aka. a supernova). What is left behind is a small and extreme dense (second only to a neutron star) which exerts an incredible gravitational force.
This attribute is what makes white dwarfs a good means for testing General Relativity. By measuring how much they deflect the light from a background star, astronomers are able to see the effect gravity has on the curvature of spacetime. This is precisely similar to what British astronomer Sir Arthur Eddington did in 1919, when he led an expedition to determine how much the Sun’s gravity deflected the light of a background star during a solar eclipse.
Known as gravitational microlensing, this same experiment was repeated by the NASA team. Using the Hubble Space Telescope, they observed Stein 2051B – a white dwarf located just 17 light-years from Earth – on seven different occasions during a two-year period. During this period, it passed in front of a background star located about 5000 light-years distant, which produced a visible deviation in the path of the star’s light.
The resulting deviation was incredibly small – only 2 milliarseconds from its actual position – and was only discernible thanks to the optical resolution of Hubble’s Wide Field Camera 3 (WFC3). Such a deviation would have been impossible to detect using instruments that predate Hubble. And more importantly, the results were consistent with what Einstein predicted a century ago.
As Kailash Sahu, an astronomer at the Space Telescope Science Institute (STScI) and the lead researcher on the project, explained in a NASA press release, this method is also an effective way to test a star’s mass. “This microlensing method is a very independent and direct way to determine the mass of a star,” he said. “It’s like placing the star on a scale: the deflection is analogous to the movement of the needle on the scale.”
The deflection measurement yielded highly-accurate results concerning the mass of the white dwarf star – roughly 68 percent of the Sun’s mass (aka. 0.68 Solar masses) – which was also consistent with theoretical predictions. This is highly significant, in that it opens the door to a new and interesting method for determining the mass of distant stars that do not have companions.
In the past, astronomers have typically determined the mass of stars by observing binary pairs and calculating their orbital motions. Much in the same way that radial velocity measurements are used by astronomers to determine if a planet has a system of exoplanets, measuring the influence two stars have on each other is used to determine how much mass each possesses.
This was how astronomers determined the mass of the Sirius star system, which is located about 8.6 light years from Earth. This binary star system consists of a white supergiant (Sirius A) and a white dwarf companion (Sirius B) which orbit each other with a radial velocity of 5.5 km/s. These measurements helped astronomers determine that Sirius A has a mass of about 2.02 Solar masses while Sirius B weighs in at 0.978 Solar masses.
And while Stein 2051B has a companion (a bright red dwarf), astronomers cannot accurately measure its mass because the stars are too far apart – at least 8 billion km (5 billion mi). Hence, this method could be used in the future wherever companion stars are unavailable or too distant. The Hubble observations also helped the team to independently verify the theory that a white dwarf’s radius can be determined by its mass.
This theory was first proposed by Subrahmanyan Chandrasekhar in 1935, the Indian-American astronomer whose theoretical work on the evolution of stars (and black holes) earned him the Nobel Prize for Physics in 1983. They could also help astronomers to learn more about the internal composition of white dwarfs. But even with an instrument as sophisticated as the WFC3, obtaining these measurements was not without its share of difficulties.
As Jay Anderson, an astronomer with the STScI who led the analysis to precisely measure the positions of stars in the Hubble images, explained:
“Stein 2051B appears 400 times brighter than the distant background star. So measuring the extremely small deflection is like trying to see a firefly move next to a light bulb. The movement of the insect is very small, and the glow of the light bulb makes it difficult to see the insect moving.”
Dr. Sahu presented his team’s findings yesterday (June 7th) at the American Astronomical Society meeting in Austin, Texas. The team’s result will also appear in the journal Science on June 9th. And in the future, the researchers plan to use Hubble to conduct a similar microlensing study on Proxima Centauri, our solar system’s closest stellar neighbor and home to the closest exoplanet to Earth (Proxima b).
It is important to note that this is by no means the only modern experiment that has validated Einstein’s theories. In recent years, General Relativity has been confirmed through observations of rapidly spinning pulsars, 3D simulations of cosmic evolution, and (most importantly) the discovery of gravitational waves. Even in death, Einstein is still making valued contributions to astrophysics!
Five time space shuttle astronaut and current NASA science chief John Grunsfeld – best known as the ‘Hubble Hugger’ for three critical and dramatic servicing and upgrade missions to the iconic Hubble Space Telescope – his decided to retire from the space agency he faithfully served since being selected as an astronaut in 1992.
“John Grunsfeld will retire from NASA April 30, capping nearly four decades of science and exploration with the agency. His tenure includes serving as astronaut, chief scientist, and head of NASA’s Earth and space science activities,” NASA announced.
Indeed, Grunsfeld was the last human to touch the telescope during the STS-125 servicing mission in 2009 when he served as lead spacewalker.
The STS-125 mission successfully upgraded the observatory to the apex of its scientific capability during five spacewalks by four astronauts and extended the life of the aging telescope for many years. Hubble remains fully operable to this day!
In April 2015, Hubble celebrated 25 years of operations, vastly outperforming its planned lifetime of 15 years.
“Hubble has given us 25 years of great service. Hopefully we’ll get another 5 to 10 years of unraveling the mysteries of the Universe,” Grunsfeld told me during a recent interview at NASA Goddard.
In his most recent assignment, Grunsfeld was NASA’s Science Chief working as the Associate Administrator for the Science Mission Directorate (SMD) at NASA Headquarters in Washington, D.C. since January 2012.
“John leaves an extraordinary legacy of success that will forever remain a part of our nation’s historic science and exploration achievements,” said NASA Administrator Charlie Bolden, in a statement.
“Widely known as the ‘Hubble Repairman,’ it was an honor to serve with him in the astronaut corps and watch him lead NASA’s science portfolio during a time of remarkable discovery. These are discoveries that have rewritten science textbooks and inspired the next generation of space explorers.”
Grunsfeld was inducted into the U.S. Astronaut Hall of Fame in 2015.
He received his PhD in physics in 1988 and conducted extensive research as an astronomer in the fields of x-ray and gamma ray astronomy and high-energy cosmic ray studies.
NASA said that Grunsfeld’s deputy Geoff Yoder will serve as SMD acting associate administrator until a successor is named.
“After exploring strange new worlds and seeking out new life in the universe, I can now boldly go where I’ve rarely gone before – home,” said Grunsfeld.
“I’m grateful to have had this extraordinary opportunity to lead NASA science, and know that the agency is well-positioned to make the next giant leaps in exploration and discovery.”
During his tenure as science chief leading NASA’s Science Mission Directorate Grunsfeld was responsible for managing over 100 NASA science missions including the Mars orbital and surface assets like the Curiosity and Opportunity Mars rovers, New Horizons at Pluto, MESSENGER, upcoming Mars 2020 rover and OSIRIS-Rex as well as Earth science missions like the Deep Space Climate Observatory, Orbiting Carbon Observatory-2, and Global Precipitation Measurement spacecraft -which resulted numerous groundbreaking science, findings and discoveries.
Dr. Grunsfeld is a veteran of five spaceflights: STS-67 (1995), STS-81 (1997), STS-103 (1999) STS-109 (2002) and STS-125 (2009), during which time he logged more than 58 days in space, including 58 hours and 30 minutes of EVA in 8 spacewalks.
He briefly retired from NASA in December 2009 to serve as Deputy Director of the Space Telescope Science Institute, in Baltimore, Maryland. He then returned to NASA in January 2012 to serve as SMD head for over four years until now.
From his NASA bio, here is a summary of John Grunsfeld’s space flight experience during five shuttle flights:
STS-67/Astro-2 Endeavour (March 2 to March 18, 1995) launched from Kennedy Space Center, Florida, and landed at Edwards Air Force Base, California. It was the second flight of the Astro observatory, a unique complement of three ultraviolet telescopes. During this record-setting 16-day mission, the crew conducted observations around the clock to study the far ultraviolet spectra of faint astronomical objects and the polarization of ultraviolet light coming from hot stars and distant galaxies. Mission duration was 399 hours and 9 minutes.
STS-81 Atlantis (January 12 to January 22, 1997) was a 10-day mission, the fifth to dock with Russia’s Space Station Mir and the second to exchange U.S. astronauts. The mission also carried the Spacehab double module, providing additional middeck locker space for secondary experiments. In 5 days of docked operations, more than 3 tons of food, water, experiment equipment and samples were moved back and forth between the two spacecraft. Grunsfeld served as the flight engineer on this flight. Following 160 orbits of the Earth, the STS-81 mission concluded with a landing on Kennedy Space Center’s Runway 33, ending a 3.9-million-mile journey. Mission duration was 244 hours and 56 minutes.
STS-103 Discovery (December 19 to December 27, 1999) was an 8-day mission, during which the crew successfully installed new gyroscopes and scientific instruments and upgraded systems on the Hubble Space Telescope (HST). Enhancing HST scientific capabilities required three spacewalks (EVAs). Grunsfeld performed two spacewalks, totaling 16 hours and 23 minutes. The STS-103 mission was accomplished in 120 Earth orbits, traveling 3.2 million miles in 191 hours and 11 minutes.
STS-109 Columbia (March 1 to March 12, 2002) was the fourth HST servicing mission. The crew of STS-109 successfully upgraded the HST, installing a new digital camera, a cooling system for the infrared camera, new solar arrays and a new power system. HST servicing and upgrades were accomplished by four crewmembers during a total of five EVAs in 5 consecutive days. As Payload Commander on STS-109, Grunsfeld was in charge of the spacewalking activities and the Hubble payload. He also performed three spacewalks totaling 21 hours and 9 minutes, including the installation of the new Power Control Unit. STS-109 orbited the Earth 165 times and covered 3.9 million miles in over 262 hours.
STS-125 Atlantis (May 11 to May 24, 2009) was the fifth and final Hubble servicing mission. After 19 years in orbit, the telescope received a major renovation that included the installation of a new wide-field camera, a new ultraviolet telescope, new batteries, a guidance sensor, gyroscopes and other repairs. Grunsfeld served as the lead spacewalker in charge of the spacewalking and Hubble activities. He performed three of the five spacewalks on this flight, totaling 20 hours and 58 minutes. For the first time while in orbit, two scientific instruments were surgically repaired in the telescope. The STS-125 mission was accomplished in 12 days, 21 hours, 37 minutes and 09 seconds, traveling 5,276,000 miles in 197 Earth orbits.
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Learn more about Hubble, NASA Mars rovers, Orion, SLS, ISS, Orbital ATK, ULA, SpaceX, Boeing, Space Taxis, NASA missions and more at Ken’s upcoming outreach events:
Apr 9/10: “NASA and the Road to Mars Human Spaceflight programs” and “Curiosity explores Mars” at NEAF (NorthEast Astronomy and Space Forum), 9 AM to 5 PM, Suffern, NY, Rockland Community College and Rockland Astronomy Club – http://rocklandastronomy.com/neaf.html
Apr 12: Hosting Dr. Jim Green, NASA, Director Planetary Science, for a Planetary sciences talk about “Ceres, Pluto and Planet X” at Princeton University; 7:30 PM, Amateur Astronomers Assoc of Princeton, Peyton Hall, Princeton, NJ – http://www.princetonastronomy.org/
Apr 17: “NASA and the Road to Mars Human Spaceflight programs”- 1:30 PM at Washington Crossing State Park, Nature Center, Titusville, NJ – http://www.state.nj.us/dep/parksandforests/parks/washcros.html
In about 4 billion years, scientists estimate that the Andromeda and the Milky Way galaxies are expected to collide, based on data from the Hubble Space Telescope. And when they merge, they will give rise to a super-galaxy that some are already calling Milkomeda or Milkdromeda (I know, awful isn’t it?) While this may sound like a cataclysmic event, these sorts of galactic collisions are quite common on a cosmic timescale.
As an international group of researchers from Japan and California have found, galactic “hookups” were quite common during the early universe. Using data from the Hubble Space Telescope and the Subaru Telescope at in Mauna Kea, Hawaii, they have discovered that 1.2 billion years after the Big Bang, galactic clumps grew to become large galaxies by merging. As part of the Hubble Space Telescope (HST) “Cosmic Evolution Survey (COSMOS)”, this information could tell us a great about the formation of the early universe.
Since it was first launched in 1990, the Hubble Space Telescope has provided people all over the world with breathtaking views of the Universe. Using its high-tech suite of instruments, Hubble has helped resolve some long-standing problems in astronomy, and helped to raise new questions. And always, its operators have been pushing it to the limit, hoping to gaze farther and farther into the great beyond and see what’s lurking there.
And as NASA announced with a recent press release, using the HST, an international team of astronomers just shattered the cosmic distance record by measuring the farthest galaxy ever seen in the universe. In so doing, they have not only looked deeper into the cosmos than ever before, but deeper into it’s past. And what they have seen could tell us much about the early Universe and its formation.
Due to the effects of special relativity, astronomers know that when they are viewing objects in deep space, they are seeing them as they were millions or even billions of years ago. Ergo, an objects that is located 13.4 billions of light-years away will appear to us as it was 13.4 billion years ago, when its light first began to make the trip to our little corner of the Universe.
This is precisely what the team of astronomers witnessed when they gazed upon GN-z11, a distant galaxy located in the direction of the constellation of Ursa Major. With this one galaxy, the team of astronomers – which includes scientists from Yale University, the Space Telescope Science Institute (STScI), and the University of California – were able to see what a galaxy in our Universe looked like just 400 million years after the Big Bang.
Prior to this, the most distant galaxy ever viewed by astronomers was located 13.2 billion light years away. Using the same spectroscopic techniques, the Hubble team confirmed that GN-z11 was nearly 200 million light years more distant. This was a big surprise, as it took astronomers into a region of the Universe that was thought to be unreachable using the Hubble Space Telescope.
In fact, astronomers did not suspect that they would be able to probe this deep into space and time without using Spitzer, or until the deployment the James Webb Space Telescope – which is scheduled to launch in October 2018. As Pascal Oesch of Yale University, the principal investigator of the study, explained:
“We’ve taken a major step back in time, beyond what we’d ever expected to be able to do with Hubble. We see GN-z11 at a time when the universe was only three percent of its current age. Hubble and Spitzer are already reaching into Webb territory.”
In addition, the findings also have some implications for previous distance estimates. In the past, astronomers had estimated the distance of GN-z11 by relying on Hubble and Spitzer’s color imaging techniques. This time, they relied on Hubble’s Wide Field Camera 3 to spectroscopically measure the galaxies redshift for the first time. In so doing, they determined that GN-z11 was farther way than they thought, which could mean that some particularly bright galaxies who’s distanced have been measured using Hubble could also be farther away.
The results also reveal surprising new clues about the nature of the very early universe. For starters, the Hubble images (combined with data from Spitzer) showed that GN-z11 is 25 times smaller than the Milky Way is today, and has just one percent of our galaxy’s mass in stars. At the same time, it is forming stars at a rate that is 20 times greater than that of our own galaxy.
As Garth Illingworth – one of the team’s investigator’s from the University of California, Santa Cruz – explained:
“It’s amazing that a galaxy so massive existed only 200 million to 300 million years after the very first stars started to form. It takes really fast growth, producing stars at a huge rate, to have formed a galaxy that is a billion solar masses so soon. This new record will likely stand until the launch of the James Webb Space Telescope.”
Last, but not least, they provide a tantalizing clue as to what future missions – like the James Webb Space Telescope – will be finding. Once deployed, astronomers will likely be looking ever farther into space, and farther into the past. With every step, we are closing in on seeing what the very first galaxies that formed in our Universe looked like.