Tag: Hubble

The tangled view of astronomers

11:06 am

A protostar in formation
Click for original image.

The uncertainty of science: The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of young stars surrounded by an edge-on dust disk. From the caption:

FS Tau is a multi-star system made up of FS Tau A, the bright star-like object near the middle of the image, and FS Tau B (Haro 6-5B), the bright object to the far right that is partially obscured by a dark, vertical lane of dust. The young objects are surrounded by softly illuminated gas and dust of this stellar nursery. The system is only about 2.8 million years old, very young for a star system. Our Sun, by contrast, is about 4.6 billion years old.

The blue lines on either side of that vertical dust lane are jets moving out from FS Tau B. The caption says their asymetrical lengths are likely due to ” mass is being expelled from the object at different rates,” but it just as easily be caused by the angle in which we see this object, making the nearer jet seem longer than the one behind.

That astronomers cannot move around such an object and see it from many angles explains the headline of this post. We can only see astronomical objects from one angle, and when they are complex objects such as this one, a large part of the research problem is disentangling the shapes we see into a coherent picture. Spectroscopy helps a lot, as it provides information about the speed and direction of different parts of the object, but even this can be enormously complicated and difficult to interpret.

Remember these facts when you read news reports about astronomical research. No matter how certain the press release sounds, its certainty is always tempered by many unknowns, some very pedestrian but fundamental.

0 comments

Hubble and Webb confirm decade-long conflict in universe’s expansion rate

8:58 am

The uncertainty of science: New data from both the Hubble and Webb space telescopes has confirmed Hubble’s previous measurement of the rate of the Hubble constant, the rate in which the universe is expanding. The problem is that these numbers still differ significantly from the expansion rate determined by the observations of the cosmic microwave background by the Planck space telescope.

Hubble and Webb come up with a rate of expansion 73 km/s/Mpc, while Planck found an expansion rate of 67 km/s/Mpc. Though this difference appears small, the scientists in both groups claim their margin of error is much smaller than that difference, which means both can’t be right.

You can read the paper for these new results here.

The bottom line mystery remains: The data is clearly telling us one of two things: 1) the many assumptions that go into these numbers might be incorrect, explaining the difference, or 2) there is something fundamentally wrong about the Big Bang theory that cosmologists have been promoting for more than a half century as the only explanation for the formation of the universe.

The solution could also be a combination of both. Our data and our theories are wrong.

3 comments

Is this really a spiral galaxy?

10:16 am

Is this really a spiral galaxy?

The uncertainty of science: The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope and released on March 4, 2024 by the PR department of the European Space Agency (ESA) as part of its Hubble Picture of the Week program. It shows what the press release claims is a spiral galaxy about 55 million light years away, seen edge on.

In this image NGC 4423 appears to have quite an irregular, tubular form, so it might be surprising to find out that it is in fact a spiral galaxy. Knowing this, we can make out the denser central bulge of the galaxy, and the less crowded surrounding disc (the part that comprises the spiral arms).

If NGC 4423 were viewed face-on it would resemble the shape that we most associate with spiral galaxies: the spectacular curving arms sweeping out from a bright centre, interspersed with dimmer, darker, less populated regions. But when observing the skies we are constrained by the relative alignments between Earth and the objects that we are observing: we cannot simply reposition Earth so that we can get a better face-on view of NGC 4423!

This picture provides a great example of the amount of assumptions that are often contained in astronomical observations. Though the data strongly suggests this is spiral, we must remember this is merely an educated guess, based on that central bulge and the dust lanes visible along the galaxy’s profile. There is actually no guarantee that this is so. As the press release also notes, astronomers are constrained by our viewpoint, and cannot change that viewpoint to get a better view to confirm this guess. For all we know, a face on veiw of this flat galaxy would reveal it has no spiral arms, but instead is mottled and chaotic, a rare type that does exist.

Astronomers do the best they can, but it is important that they (and we) always recognize the limitations.

3 comments

A galaxy with a tail of star-forming clusters

10:34 am

A galaxy with a tail of newborn stars
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of twelve different galaxies that have long tails. In this case, the galaxy is named Arp-Madore 1054-325, and the tail that trails off in the upper left is caused by the gravity of the nearby neighboring galaxy, which I think is the patch of stars just below it. Within it are many star clusters where new stars are forming. From the caption:

A team of astronomers used a combination of new observations and archival data to get ages and masses of tidal tail star clusters. They found that these clusters are very young — only 10 million years old. And they seem to be forming at the same rate along tails stretching for thousands of light-years. “It’s a surprise to see lots of the young objects in the tails. It tells us a lot about cluster formation efficiency,” said lead author Michael Rodruck of Randolph-Macon College in Ashland, Virginia.

Before the mergers, the galaxies were rich in dusty clouds of molecular hydrogen that may have simply remained inert. But the clouds got jostled and bumped into each other during the encounters. This compressed the hydrogen to the point where it precipitated a firestorm of star birth.

In some ways this galaxy portends one possible future of the Milky Way, after it collides with the nearby Andromeda galaxy in the far future.

2 comments

A soft but dim spiral

10:51 am

A soft but dim spiral
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of nearby galaxies in which supernovae had previously been detected.

This softly luminous galaxy — lying in the constellation Hercules, about 110 million light-years from Earth — seems outshone by the sparkling foreground stars that surround it. The type II supernova which took place in this galaxy in 2019, while no longer visible in this image, definitely outshone the galaxy at the time!

What amazes me about this somewhat dim spiral galaxy is its beautiful structure, its two spiral arms coiling outward in perfect symmetry. And yet, we are looking at a object that is almost entirely empty space, hundreds of thousands of light years across. Somehow the almost infinitesimal force of gravity at those distances is still able to shape the arms, and the spirals.

3 comments

The future of astronomy, as seen by PBS News in 1991

6:01 pm

An evening pause: Today is the 75th anniversary of the moment astonomers took the lens cap off the Hale Telescope at Palomar, what astronomers call “first light.” In honor of this anniversary, tonight’s evening pause is a somewhat well-done news piece produced by PBS in 1991, describing the state of ground-based astronomy at that time, which was actually another key moment in the history of astronomy. After decades of no advancement following the Hale telescope, the field was about to burst out with a whole new set of telescopes exceeding it significantly, based on new technologies. We today have become accustomed to those new telescopes, but in 1991 they were still incomplete or on the drawing board.

This was also after the launch of Hubble but before it was fixed, so this moment was also a somewhat dark time for astronomy in general. Watching this news piece gives you a sense of history, as seen by those living at that time. It also lets you see some good examples of the standard tropes of reporters as well as some astronomers. They always say this new telescope (whatever and whenever it is) is going to allow us to discover the entire history of the universe, even though it never can, and never will.

Hat tip Mike Nelson.

15 comments

Merging galaxies

10:02 am

Merging galaxies
Click for original image.

Time for another cool image from the Hubble Space Telescope. The picture to the right, cropped, reduced, and sharpened to post here, was taken by Hubble to study “the overall physical characteristics of galaxies and their star formation.”

What the picture however reveals best is the ongoing merger of three galaxies.

Arp 300 consists of two interacting galaxies, UGC 05028 (the smaller face-on spiral galaxy) and UGC 05029 (the larger face-on spiral). Likely due to its gravitational dance with its larger partner, UGC 05028 has an asymmetric, irregular structure, which is not as visible from ground-based telescopes but is quite distinct in this new image from NASA’s Hubble Space Telescope. The bright knot visible to the southeast of the center of UGC 05028 may be the remnant of another small galaxy that is in the process of merging with that galaxy.

As always with Hubble galaxy images, there are a plethora of other background galaxies scattered about, including what appears to be another merger in the center right of two elliptical galaxies. In fact, except for one star in the lower right (with the four spikes), every other object in this photo is a galaxy of many shapes and distances.

0 comments

Webb confirms the unusual shape of early galaxies as seen by Hubble

9:52 am

Earth galaxies shapes, as seen by Webb in infrared
Click for original image.

The uncertainty of science: The infrared view of the Webb Space Telescope appears to have confirmed and even underlined the unusual shapes of many early galaxies as previously seen by the Hubble Space Telescope.

Researchers analyzing images from NASA’s James Webb Space Telescope have found that galaxies in the early universe are often flat and elongated, like surfboards and pool noodles – and are rarely round, like volleyballs or frisbees. “Roughly 50 to 80% of the galaxies we studied appear to be flattened in two dimensions,” explained lead author Viraj Pandya, a NASA Hubble Fellow at Columbia University in New York. “Galaxies that look like pool noodles or surfboards seem to be very common in the early universe, which is surprising, since they are uncommon nearby.”

The team focused on a vast field of near-infrared images delivered by Webb, known as the Cosmic Evolution Early Release Science (CEERS) Survey, plucking out galaxies that are estimated to exist when the universe was 600 million to 6 billion years old.

While most distant galaxies look like surfboards and pool noodles, others are shaped like frisbees and volleyballs. The “volleyballs,” or sphere-shaped galaxies, appear the most compact type on the cosmic “ocean” and were also the least frequently identified. The frisbees were found to be as large as the surfboard- and pool noodle-shaped galaxies along the “horizon,” but become more common closer to “shore” in the nearby universe.

The galaxies also appear generally far less massive than galaxies in the near universe, which fits with the Big Bang theory that says they had less time to grow.

The press release notes that the sample size is still very small, and further observations will be required to confirm whether these shapes are common in the early universe.

0 comments

One spiral galaxy eating another

9:51 am

One spiral galaxy eating another
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of an on-going survey of known pecular-looking galaxies. This pair is believed to be 570 million light years away. From the caption:

Galaxies are composed of stars and their solar systems, dust and gas. In galactic collisions, therefore, these constituent components may experience enormous changes in the gravitational forces acting on them. In time, this completely changes the structure of the two (or more) colliding galaxies, and sometimes ultimately results in a single, merged galaxy. That may well be what results from the collision pictured in this image. Galaxies that result from mergers are thought to have a regular or elliptical structure, as the merging process disrupts more complex structures (such as those observed in spiral galaxies). It would be fascinating to know what Arp 122 will look like once this collision is complete . . . but that will not happen for a long, long time.

From our viewpoint, the spiral galaxy at the top appears warped by the gravitational pull of the face-on spiral at the bottom, as if it is being sucked into the bottom galaxy. In truth, both galaxies are pulling on each other. If we could circle around and see them in three dimensions we would almost certainly see distortions in the bottom spiral as well.

10 comments

Hubble detects changes in atmosphere of exoplanet

10:16 am

Using data from collected in 2016, 2018, and 2019 combined with computer simulations, scientists now believe they have detected changes in the atmosphere of the exoplanet WASP-121b, also nicknamed Tylos.

The Jupiter-sized planet orbits a star about 880 light years away.

WASP-121 b is so close to its parent star that the orbital period is only 1.27 days. This close proximity means that the planet is tidally locked so that the same hemisphere always faces the star, in the same way that our Moon always has the same side pointed at Earth. Daytime temperatures approach 3,450 degrees Fahrenheit (2,150 degrees Kelvin) on the star-facing side of the planet.

The team used four sets of Hubble archival observations of WASP-121 b. The complete data-set included observations of WASP-121 b transiting in front of its star (taken in June 2016); WASP-121 b passing behind its star, also known as a secondary eclipse (taken in November 2016); and the brightness of WASP-121 b as a function of its phase angle to the star (the varying amount of light received at Earth from an exoplanet as it orbits its parent star, similar to our Moon’s phase-cycle). These data were taken in March 2018 and February 2019, respectively.

A computer model was then used to fill in the gaps and provide a simulation of the hot temperatures of that exoplanet’s atmosphere over time. Two videos of that simulation are available at the link.

There of course is a lot of uncertainty in this result, though the fundamental discovery of changes is important. This data proves there is weather on such alien planets, even if that weather is so alien we really don’t understand it in the slightest based on the available data on hand.

2 comments

Galaxies galore, near and far

9:08 am

Galaxies galore, and near and far

Cool image for the day after Christmas! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope, and shows a cluster of galaxies that all seem near each other. However, as the caption notes,

[W]hilst NGC 1356 [the largest spiral] and LEDA 95415 [close by its left] appear to be so close that they must surely be interacting, the former is about 550 million light-years from Earth and the latter is roughly 840 million light-years away, so there is nearly a whopping 300 million light-year separation between them. That also means that LEDA 95415 is likely nowhere near as [small] as it appears to be.

On the other hand, whilst NGC 1356 and IC 1947 [farthest to the left] seem to be separated by a relative gulf in this image, IC 1947 is only about 500 million light-years from Earth. The angular distance apparent between them in this image only works out to less than four hundred thousand light-years, so they are actually much much closer neighbours in three-dimensional space than NGC 1356 and LEDA 95415!

The two galaxies farthest apart in this image are actually close enough together to interact significantly. Though this picture doesn’t have the resolution to see it, there is likely a stream of stars between the two.

Note also the numerous tiny other galaxies scatterered throughout the picture. In fact, except for three stars (the objects with the north-south-east-west spikes), every object is a galaxy holding stars too numerous to count.

1 comment

New Hubble image of Saturn

10:04 am

Saturn and its rings, as seen by Hubble

The annotated image above was taken by the Hubble Space Telescope on October 22, 2023, showing Saturn, its glorious rings, and several of its dozens of moons from a distance of about 850 million miles. For the unannotated version, go here. Of all the features, the spokes in the rings are the most intriguing.

Saturn’s spokes are transient features that rotate along with the rings. Their ghostly appearance only persists for two or three rotations around Saturn. During active periods, freshly-formed spokes continuously add to the pattern. In 1981, NASA’s Voyager 2 first photographed the ring spokes. Hubble continues observing Saturn annually as the spokes come and go. This cycle has been captured by Hubble’s Outer Planets Atmospheres Legacy (OPAL) program that began nearly a decade ago to annually monitor weather changes on all four gas-giant outer planets.

Hubble’s crisp images show that the frequency of spoke apparitions is seasonally driven, first appearing in OPAL data in 2021 but only on the morning (left) side of the rings. Long-term monitoring shows that both the number and contrast of the spokes vary with Saturn’s seasons. Saturn is tilted on its axis like Earth and has seasons lasting approximately seven years.

This year, these ephemeral structures appear on both sides of the planet simultaneously as they spin around the giant world. Although they look small compared with Saturn, their length and width can stretch longer than Earth’s diameter!

Though the origin of the spokes remains unsolved, the leading theory proposes they are caused by interactions between Saturn’s magnetic field and the seasonal changes in solar radiation.

0 comments
1 … 6 7 8 9 10 … 15