Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
Amazing sights abound all across the Universe.
This densely populated region of space is focused on galaxy cluster SDSS J1004+4112, and showcases several objects that appear multiply imaged owing to gravitational lensing. Once called a “five star” lens, the star-like appearances seen near the cluster’s center are actually the same quasar imaged five times in the same field-of-view: a deceptive trick of light and gravity.
But these ten examples are very different from what their appearances indicate.
Galaxy NGC 105, face-on and with many spectacular features, appears to be merging and overlapping with a smaller galaxy shown to its upper-left: PGC 212515. However, this appearance is deceptive; these galaxies are not related and are not even in the same vicinity as one another.
10.) Apparently “merging” galaxy NGC 105.
The “background” galaxy found very close to NGC 105, PGC 212515, is not interacting with its larger neighbor. In fact, these are not neighboring galaxies at all, but are separated by over 100 million light-years; they just happen to be along the same line-of-sight. The lack if tidal distortion and stellar streams is a telltale sign of this cosmic coincidence.
The “smaller” galaxy, PGC 212515, is 100+ million light-years separated from NGC 105.
Globular clusters are round, symmetric collections of stars filled primarily with older stars: formed in bursts many billions of years ago. This object, although it looks like a globular cluster visually, is some ~200,000 light-years away and consists exclusively of young stars; it is instead an open star cluster, but one that has not yet begun to dissociate.
9.) “Globular cluster” NGC 411.
While globular clusters are always round and typically consist of very old stars, open star clusters are newly formed and have a variety of concentrations and shapes. Two open star clusters are shown here: one older and more spherical (at left), NGC 265, and one younger and more irregular (at right), NGC 290. Like NGC 411, both of these open clusters are present in the Small Magellanic Cloud.
This spherical stellar collection is a young open star cluster, not a globular.
The dark nebula Barnard 68, now known to be a molecular cloud called a Bok globule, has a temperature of less than 20 K. It’s still quite warm when compared with the temperatures of the cosmic microwave background, however, and is definitely not a hole in the Universe.
8.) “Hole in the Universe” Barnard 68.
This animation shows the Bok globule Barnard 68 in a variety of visible and infrared wavelengths. As the longer wavelengths reveal, this is not a hole in the Universe but simply a dusty cloud of gas, where the longer (redder) wavelengths of light penetrate and pass through the dust. As dust clouds form and dissipate, the dust density can be revealed by examining the light blocked and transmitted by fixed, background objects.
This dark molecular cloud blocks visible, but transmits infrared, wavelengths.
The dying red giant star, R Sculptoris, exhibits a very unusual set of ejecta when viewed in millimeter and submillimeter wavelengths: revealing a spiral structure. This is thought to be due to the presence of a binary companion: something our own Sun lacks but that approximately half of the stars in the universe possess. Stars lose approximately half of their mass — some more, and some less — as they evolve through the red giant and AGB phases and into an eventual planetary nebula/white dwarf combination.
7.) “Spiral structure” R Sculptoris.
A carbon-rich star on the asymptotic giant branch, R Sculptoris is blowing off its outer layers. The close-up view of the central star, in infrared light (at right), shows that giant clumps of stellar dust are “peeling away” from the shedding star, a strong indication of a (yet unseen) binary companion.
This non-galaxy is a dying, giant star orbiting a massive, hidden companion star.
The galaxy shown here, DDO 68 (UGC 5340), was once thought to be a newly-formed galaxy located very close by in our cosmic neighborhood: just 39 million light-years away. However, by studying the galaxy in great detail, an older population of stars was found inside, disproving the notion that this galaxy formed recently in cosmic history.
6.) “Newborn” nearby galaxy DDO 68.
The dwarf galaxy DDO 68 (UGC 5340) is only about 40 million light-years away, and contains a huge, bright population of recently-formed stars. In 2019, new Hubble Space Telescope data detected a previously unseen merging companion, which confirms the picture of hierarchical mergers, even at late times, on the scales of dwarf galaxies.
An infalling dark, low-mass companion has triggered new, recent star-formation in this dwarf galaxy.
This composite image of the Pulsar Wind Nebula, PSR B1509-58, was created with NuSTAR and Chandra data. The expelled material arising from a now-exploded star is heated and accelerated by the rapidly-spinning pulsar and its associated magnetic field, causing the surrounding environment to emit high-energy X-rays. The red region is a nearby cloud of material known as RCW 89.
5.) The “Hand of God” in space.
A small, dense object only twelve miles in diameter is responsible for this X-ray nebula that spans ~150 light-years. This pulsar is spinning around almost 7 times a second and has a magnetic field at its surface estimated to be 15 trillion times stronger than the Earth’s magnetic field. This pulsar wind nebula exhibits spectacular details that are revealed with NASA’s Chandra X-ray observatory, with the different colors highlighting different X-ray energies: the red color, at top-right, indicates the nearby presence of a cloud of gas unrelated to the pulsar itself.
Credit: NASA/CXC/CfA/P. Slane et al.
These heated cloud emit high-energy X-rays, showcasing energetic winds created by a young pulsar.
This view show’s the famous Cat’s eye nebula, as seen by Hubble (L) and JWST’s MIRI instrument (R). Although the JWST image was used in calibration and commissioning, both images reveal an intricate set of knotted, asymmetrical shapes within the nebula. Although no visual binary companion is observable, the shapes of these features strongly suggest that a massive one is present.
Credit: Team MIRI
4.) The “Cat’s Eye” Nebula.
The Cat’s Eye Nebula is a visually spectacular example of the fate of Sun-like stars: blowing off their outer layers and then contracting, where they heat up and ionize the surrounding material. Here, the intricate, layered, asymmetrical shape of this nebula suggests a binary companion’s presence, even though the companion is unseen. Previously expelled hydrogen creates a much larger spatial structure than the ionized material itself.
Credit: Nordic Optical Telescope and Romano Corradi (Isaac Newton Group of Telescopes, Spain)
A bright planetary nebula with an unseen binary companion, its expelled material extends across multiple light-years.
La Flaca, the “skinny” counterpart to the “fat” cluster that lenses it, El Gordo, is the longest, straightest arc ever seen due to gravitational lensing. JWST data has revealed several new point-like features within the line of La Flaca that also experience and contribute to the cumulative gravitational lensing effect.
3.) The long, thin “La Flaca” galaxy.
This image shows the most interesting regions of the El Gordo galaxy cluster as imaged by JWST and the PEARLS collaboration: the regions where gravitational lensing effects are strongest. Although the light from the main galaxy cluster comes to us from 7.6 billion years ago, even more distant background objects have their light stretched, distorted, and magnified by the foreground cluster. El Gordo, for its time in the Universe, is the largest, most massive galaxy cluster known, with “La Flaca” prominently visible to the left of center.
This normal spiral galaxy experiences the most severe linear distortion from foreground gravitational lensing.
This image showcases the massive, distant galaxy cluster Abell S1063. As part of the Hubble Frontier Fields program, this is one of six galaxy clusters to be imaged for a long time in many wavelengths at high resolution. The diffuse, bluish-white light shown here is actual intracluster starlight, which was captured for the first time only in 2018: it traces out the dark matter. Both strong lensing, which creates arcs and multiple images, and weak lensing, which distorts the shapes of background galaxies, are on display here.
Credit: NASA, ESA, and M. Montes (University of New South Wales)
2.) Circularly surrounded galaxy cluster Abell S1063.
Gravitational lensing comes in two varieties. There’s strong lensing, which severely moves apparent positions, can create multiple images of the same object, and magnifies and distorts shape and position, especially close to the greatest mass concentration. And there’s also weak lensing, which re-orients the apparent shapes of galaxies to be elongated in circular paths surrounding the largest source(s) of mass.
Distorted foreground galaxy shapes are phantasmal: arising from weak and strong gravitational lensing.
This multi-panel image showcases the optically observable star that’s the visible part of the binary Gaia BH1 system. Located ~1500 light years away, the star is observed to display a helical motion, implying the existence of a central, more massive black hole, making Gaia BH1 the closest known black hole to Earth since the time of its discovery in 2022/2023.
1.) Helically-moving star Gaia BH1.
Overview of the radial velocities for Gaia-BH1 as obtained by the LAMOST survey and from follow-up observations with the MagE, GMOS, XSHOOTER, ESI, FEROS and HIRES spectrographs. Points with error bars are measurements, gray lines are drawn from the posterior when jointly fitting thse radial velocity spectra and the Gaia astrometric constraints.
Our closest known black hole orbits an observable, Sun-like star.
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.
Sign up for the Starts With a Bang newsletter
Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all.
