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  • August 14, 2020 11:34 AM | Anonymous member (Administrator)

    Hot 'blob' points to a neutron star lurking in Supernova 1987A

    Astronomers have long suspected a city-sized neutron star hides within the dusty shroud of SN 1987A. And now, they’re closer than ever to proving their case.

    By Yvette Cendes  |  Published: Thursday, August 6, 2020



    Astronomers have found new, compelling evidence that Supernova 1987A harbors a neutron star (blue-white) within a newly imaged 'blob' of extremely hot dust (red), as seen in this artist’s concept.

    NRAO/AUI/NSF, B. Saxton

    On February 24, 1987, an unexpected cosmic explosion rocked the astronomical community. Dubbed Supernova 1987A (SN 1987A), the fiery event — triggered by the implosion of a massive star — was the closest observed supernova to Earth since the invention of the telescope. It didn’t occur in our galaxy, though. SN 1987A self-destructed within the Large Magellanic Cloud, which is a satellite galaxy of the Milky Way that resides some 170,000 light-years from Earth. Nonetheless, SN 1987A was still so bright that naked-eye observers could see it for several weeks.

    But the extraordinary sight of a nearby supernova lingering in Earth’s night sky isn’t the only thing SN 1987A bestowed upon us. It also gave astronomers an unprecedented opportunity to investigate what triggers supernovae, as well as how such powerful blasts ripple through their surroundings. In fact, we can see the shockwave from SN 1987A still speeding outward today, interacting with clouds of dust that encircle the original site of the cosmic explosion.

    This time-lapse shows how Supernova 1987A's shock wave explodes outward over the course of 25 years.

    Credit: Yvette Cendes/University of Toronto/Leiden Observatory

    However, an enduring mystery remains: What did SN 1987A leave behind? According to new research, the answer is likely a neutron star.

    The corpse of SN 1987A 

    For quite some time, astronomers have assumed SN 1987A initially left behind a neutron star. That’s because a few hours before the supernova’s light reached us, they detected an influx of neutrino particles washing over Earth, as would be expected if a supernova erupted nearby. These nearly unstoppable particles zip straight through the dense material present during a budding supernova — unlike light, which gets held up for a bit. In fact, SN 1987A was the very first time scientists ever detected neutrinos from beyond our solar system.

    But even though these neutrinos almost certainly came from the birth of a neutron star in SN 1987A, astronomers aren’t sure whether that neutron star lives on, or rather quickly collapsed into a black hole. And despite decades of monitoring the site, observers have yet to find convincing signs of a compact object lurking near the center of SN 1987A. At least, until now.

    In a new paper published July 30 in The Astrophysical Journal, astronomers report they’ve found compelling evidence that SN 1987a is still harboring a neutron star, which would make it the youngest such stellar corpse yet known. (The previous record holder, called Cassiopeia A, is estimated to be about 330 years old.) The astronomers carried out the study using the Atacama Large Millimeter/submillimeter Array (ALMA) — a radio telescope in Chile that’s able to peer through obscuring dust. These new, extremely high-resolution images revealed a hot “blob” lurking in the core of SN 1987A.


    The Atacama Large Millimeter/submillimeter Array (ALMA) captured high-resolution images to reveal a hot, slightly off-center “blob” (inset to left) within the core of Supernova 1987A. The material seen by ALMA in radio wavelengths is colored red and yellow. Hubble’s visible view is displayed in green, and Chandra’s X-ray view is shown in blue.

    ALMA (ESO/NAOJ/NRAO), P. Cigan and R. Indebetouw; NRAO/AUI/NSF, B. Saxton; NASA/ESA

    However, the blob itself is not the neutron star. Because neutron stars compress about 1.4 times the mass of the Sun into a sphere roughly 15 miles (25 kilometers) wide, they are impossible to see directly. Instead, the newly discovered blob seems to be a giant gas cloud that dramatically outshines its surroundings, and it’s located right where astronomers think SN 1987A’s neutron star should be.

    “There has to be something in the cloud that has heated up the dust and which makes it shine,” explained coauthor Mikako Matsuura of Cardiff University in a press release. At its longest, the blob spans about 4,000 astronomical units — where one astronomical unit is the average Earth-Sun distance — and it’s estimated to have a temperature of some 9 million degrees Fahrenheit (5 million degrees Celsius). “That’s why we suggest that there is a neutron star hiding inside the dust cloud,” Matsuura added.

    This blob is not exactly at the center of SN 1987A, though; it’s slightly offset. But that’s not a bug in the theory, that’s a feature. Astronomers have long suspected that SN 1987A exploded asymmetrically, flinging more material in one direction than the other. Per Newton’s third law of motion, such an asymmetric blast would have “kicked away” the neutron star in the opposite direction at hundreds of miles per second. So, by simply calculating how far the neutron star traveled through space during the past 30-some years, the astronomers can predict its offset from the center of SN 1987A. As it turns out, it’s precisely where they found the blob in the ALMA images.

    Want to learn more about pulsars and other extreme objects in our universe? Check out our free downloadable eBook: Exotic objects: Black holes, pulsars, and more.

    Now that astronomers have likely found the location of the neutron star within SN 1987A — and nicknamed it “NS 1987A” — the real quest for understanding can begin.

    For starters, researchers really want to know whether NS 1987A is a pulsar, which is a neutron star that emits a powerful beam of radio radiation as it rotates. (Remember, all pulsars are neutron stars. But not all neutron stars are pulsars). While astronomers aren’t exactly sure what mechanism produces a pulsar’s radio jet, they think it’s related to factors like the star’s spin and magnetic field. But so far, astronomers haven’t detected any such radio pulses from the direction of SN 1987A. Plus, the blob’s current amount of energy doesn’t seem to allow for extra energy coming from pulses within.

    To definitively determine whether NS 1987A is a pulsar or just a run-of-the-mill neutron star, astronomers must continue to refine the estimated mass and temperature of the blob. Then, by closely seeking out periodic variations in the blob’s brightness, they might be able to tie any flickers to the consistent rhythm of a pulsar within.

    Until then, however, researchers are simply happy that a decades-old mystery about what lurks in the core of SN 1987A is likely laid to rest. But even so, you can bet astronomers won’t stop tracking the aftermath of the cosmic explosion anytime soon.

  • August 14, 2020 11:31 AM | Anonymous member (Administrator)

    Aug. 13, 2020

    Hubble Finds That Betelgeuse's Mysterious Dimming Is Due to a Traumatic Outburst

    Observations by NASA's Hubble Space Telescope are showing that the unexpected dimming of the supergiant star Betelgeuse was most likely caused by an immense amount of hot material ejected into space, forming a dust cloud that blocked starlight coming from Betelgeuse's surface.

    Hubble researchers suggest that the dust cloud formed when superhot plasma unleashed from an upwelling of a large convection cell on the star's surface passed through the hot atmosphere to the colder outer layers, where it cooled and formed dust grains. The resulting dust cloud blocked light from about a quarter of the star's surface, beginning in late 2019. By April 2020, the star returned to normal brightness.

    Betelgeuse is an aging, red supergiant star that has swelled in size due to complex, evolving changes in its nuclear fusion furnace at the core. The star is so huge now that if it replaced the Sun at the center of our solar system, its outer surface would extend past the orbit of Jupiter.

    The unprecedented phenomenon for Betelgeuse's great dimming, eventually noticeable to even the naked eye, started in October 2019. By mid-February 2020, the monster star had lost more than two-thirds of its brilliance.

    four illustrations of a red-hued star expelling gas, bringing the star into slight shadow

    This four-panel graphic illustrates how the southern region of the rapidly evolving, bright, red supergiant star Betelgeuse may have suddenly become fainter for several months during late 2019 and early 2020. In the first two panels, as seen in ultraviolet light with the Hubble Space Telescope, a bright, hot blob of plasma is ejected from the emergence of a huge convection cell on the star's surface. In panel three, the outflowing, expelled gas rapidly expands outward. It cools to form an enormous cloud of obscuring dust grains. The final panel reveals the huge dust cloud blocking the light (as seen from Earth) from a quarter of the star's surface.

    Illustration credit: NASA, ESA, and E. Wheatley (STScI)

    This sudden dimming has mystified astronomers, who scrambled to develop several theories for the abrupt change. One idea was that a huge, cool, dark "star spot" covered a wide patch of the visible surface. But the Hubble observations, led by Andrea Dupree, associate director of the Center for Astrophysics | Harvard & Smithsonian (CfA), Cambridge, Massachusetts, suggest a dust cloud covering a portion of the star.

    Several months of Hubble's ultraviolet-light spectroscopic observations of Betelgeuse, beginning in January 2019, yield a timeline leading up to the darkening. These observations provide important new clues to the mechanism behind the dimming.

    Hubble captured signs of dense, heated material moving through the star's atmosphere in September, October, and November 2019. Then, in December, several ground-based telescopes observed the star decreasing in brightness in its southern hemisphere.

    “With Hubble, we see the material as it left the star’s visible surface and moved out through the atmosphere, before the dust formed that caused the star to appear to dim,” Dupree said. “We could see the effect of a dense, hot region in the southeast part of the star moving outward.

    "This material was two to four times more luminous than the star's normal brightness," she continued. "And then, about a month later, the south part of Betelgeuse dimmed conspicuously as the star grew fainter. We think it is possible that a dark cloud resulted from the outflow that Hubble detected. Only Hubble gives us this evidence that led up to the dimming."

    The team's paper will appear online Aug. 13 in The Astrophysical Journal.

    Massive supergiant stars like Betelgeuse are important because they expel heavy elements such as carbon into space that become the building blocks of new generations of stars. Carbon is also a basic ingredient for life as we know it.

    Tracing a Traumatic Outburst

    Dupree's team began using Hubble early last year to analyze the behemoth star. Their observations are part of a three-year Hubble study to monitor variations in the star's outer atmosphere. Betelgeuse is a variable star that expands and contracts, brightening and dimming, on a 420-day cycle.

    Hubble's ultraviolet-light sensitivity allowed researchers to probe the layers above the star's surface, which are so hot — more than 20,000 degrees Fahrenheit — they cannot be detected at visible wavelengths. These layers are heated partly by the star's turbulent convection cells bubbling up to the surface.

    Hubble spectra, taken in early and late 2019, and in 2020, probed the star's outer atmosphere by measuring magnesium II (singly ionized magnesium) lines. In September through November 2019, the researchers measured material moving about 200,000 miles per hour passing from the star's surface into its outer atmosphere.

    Related: NASA Satellite’s Lone View of Betelgeuse Reveals More Strange Behavior

    For several weeks in summer 2020, NASA’s STEREO had the solar system’s best view of the star Betelgeuse, revealing more unexpected dimming by the star.

    This hot, dense material continued to travel beyond Betelgeuse's visible surface, reaching millions of miles from the seething star. At that distance, the material cooled down enough to form dust, the researchers said.

    This interpretation is consistent with Hubble ultraviolet-light observations in February 2020, which showed that the behavior of the star's outer atmosphere returned to normal, even though visible-light images showed that it was still dimming.

    Although Dupree does not know the outburst's cause, she thinks it was aided by the star's pulsation cycle, which continued normally though the event, as recorded by visible-light observations. The paper's co-author, Klaus Strassmeier, of the Leibniz Institute for Astrophysics Potsdam, used the institute's automated telescope called STELLar Activity (STELLA), to measure changes in the velocity of the gas on the star's surface as it rose and fell during the pulsation cycle. The star was expanding in its cycle at the same time as the upwelling of the convective cell. The pulsation rippling outward from Betelgeuse may have helped propel the outflowing plasma through the atmosphere.

    Dupree estimates that about two times the normal amount of material from the southern hemisphere was lost over the three months of the outburst. Betelgeuse, like all stars, is losing mass all the time, in this case at a rate 30 million times higher than the Sun.

    Betelgeuse is so close to Earth, and so large, that Hubble has been able to resolve surface features – making it the only such star, except for our Sun, where surface detail can be seen.

    Hubble images taken by Dupree in 1995 first revealed a mottled surface containing massive convection cells that shrink and swell, which cause them to darken and brighten.

    A Supernova Precursor?

    The red supergiant is destined to end its life in a supernova blast. Some astronomers think the sudden dimming may be a pre-supernova event. The star is relatively nearby, about 725 light-years away, which means the dimming would have happened around the year 1300. But its light is just reaching Earth now.

    "No one knows what a star does right before it goes supernova, because it's never been observed," Dupree explained. "Astronomers have sampled stars maybe a year ahead of them going supernova, but not within days or weeks before it happened. But the chance of the star going supernova anytime soon is pretty small."

    Dupree will get another chance to observe the star with Hubble in late August or early September. Right now, Betelgeuse is in the daytime sky, too close to the Sun for Hubble observations. But NASA's Solar Terrestrial Relations Observatory (STEREO) has taken images of the monster star from its location in space. Those observations show that Betelgeuse dimmed again from mid-May to mid-July, although not as dramatically as earlier in the year.

    Dupree hopes to use STEREO for more follow-up observations to monitor Betelgeuse's brightness. Her plan is to observe Betelgeuse again next year with STEREO when the star has expanded outward again in its cycle to see if it unleashes another petulant outburst.

    Claire Andreoli
    NASA's Goddard Space Flight Center, Greenbelt, Md.

    Donna Weaver / Ray Villard
    Space Telescope Science Institute, Baltimore
    410-338-4493 / 410-338-4514 /

    Andrea Dupree
    CfA | Harvard & Smithsonian, Cambridge, Mass.

  • July 12, 2020 1:19 PM | Anonymous member (Administrator)

    I got to see the current bright comet (Neowise) this morning.  The attached file documents how it appeared.  

    Comet Neowise.pdf

  • July 01, 2020 3:45 PM | Anonymous member (Administrator)

    For those interested in Citizen Science, I did a presentation for the club a couple of years ago. In case you missed it, here is the link to the slideshow, with some excellent projects that you can participate in:

  • June 28, 2020 7:26 PM | Anonymous member

    Check out the contest winners of the International Dark Sky Associations "Capture the Dark Photography" Contest.

  • May 24, 2020 10:44 AM | Anonymous member

    Nancy Roman Made Hubble Happen, And Its Successor Is Named For Her - Forbes 

  • May 23, 2020 1:49 PM | Anonymous member

    Star Gazing Guide

    May 22-28, 2020

    Bare Dark Sky Observatory

    Greetings Fellow StarGazers!

    It’s hard to believe we’re closing in on summer. The nights are getting warmer, which makes for even more motivation to get outside under a star-filled night sky. The Bare Dark Sky Observatory is still six weeks away from re-opening, but our initial July 10 & 11 community evening events are filling up fast. While we usually allow a capacity of up to 25 people per event, we have opted to cap them at 20 for the time being. At that number we believe that we can safely adhere to the social distancing guidelines. Click HERE for access to BDSO tickets through Eventbrite.

    What’s Up

    Most seasoned amateur astronomers will tell you that May is kinda one of those transitional months. The planets aren’t coming into view until the wee hours, and the most fun deep sky objects require a telescope. However, a pair of binoculars and a comfortable lawn chair can definitely make for some memorable star and constellation hopping. Side note: Finding objects by “jumping off” nearby stars is called star hopping, and is a great way to learn the night sky without a computerized telescope. We suggest you keep your favorite night sky app or sky map close at hand. The good news is it looks like we’re in for a special treat …

    Comet Swan Update

    In last week’s Star Gazing Guide we mentioned the arrival of Comet Swan (pictured below) as it continues to make its visible journey into the northern hemisphere. Hopefully, several of you will make an effort to check it out. Our first best opportunity to see Comet Swan may be an hour after sundown beginning Monday, May 25 as it cruises through the Perseus constellation towards Auriga in the northwest sky. On May 27 Swan will reach its perihelion (closest point to our Sun – 40 million miles) and will supposedly reach its optimal brightness. If you miss seeing it in the early evenings, try catching it about an hour before sunrise in the north-northeast sky. Hopefully, you will see a nice green fireball with a long blue-green coma or tail of gas and dust. We would love to hear about any sightings and see any photos that you can share. As a heads up, comets are very unpredictable and Swan may deliver a surprise or two. In other words, it could brighten beyond expectations or quickly fizzle out on us. While telescopes and binoculars should provide easy viewing of Comet Swan, we’re hopeful for some rare magnitude 4 or 5 naked eye vistas. The last naked eye comet sighting in our area was Hale-Bopp back in 1997.


    One major class of deep sky objects is star clusters. Star clusters are basically groups of stars that come in two distinct types: openclusters and globularclusters.

    Open Clusters are loose groups of several thousand stars or less. Many can be easily seen with the naked eye, like Pleiades (M45), and the Beehive (M44) (pictured below) in the constellation Cancer. Some are so easily seen that our BDSO guests will notice them before we even point them out. Those with telescopes usually find that viewing open star clusters with lower power eyepieces is preferable to higher power eyepieces because the wider field of view helps us see the most stars. Furthermore, binoculars help us more easily see the entire star cluster.

    The stars in an open cluster are similar in age since they form out of the same stellar nursery within giant molecular clouds. So far, over a thousand open clusters have been discovered. One open star cluster (which is actually a constellation) you might want to check out with your binoculars is Coma Berenices, located next to Leo the Lion. The story behind Berenices is worth looking up since she was an actual Egyptian queen whose beautiful blond hair was sacrificially cut off to make good on a promise when her husband returned victorious from a war against Syria. Folklore has it that it was Berenices’s locks of hair that Zeus supposedly decided to display in the night sky for all time.

    Globular Clusters are immense groups of stars tightly bound by gravitational attraction. Besides Saturn, Jupiter, Moon craters, and the Milky Way, viewing globular clusters is also a major crowd-pleaser at BDSO. Although several theories exist, the origin of globular clusters still remains a mystery. Many globular clusters can be spotted through binoculars, though very few with the naked eye. Since these clusters contain from ten thousand up to several million stars, without the magnification of a telescope most resemble blurry fuzz balls.

    Our favorite, which is pictured below, the Hercules Great Globular (M13), is considered by many to be the most spectacular globular cluster visible in the northern hemisphere. It is only second in popularity to Omega Centauri, the largest globular cluster in the Milky Way which is only visible from the southern hemisphere. If you can find the Hercules constellation, either with a sky map app or otherwise, then M13 is pretty easy to locate. It sits about one-third of the way between two bright stars in the easily recognizable “keystone” trapezoid-shaped asterism, often referred to as Hercules’s head. Currently, M13 is in the top side of the keystone, but because everything moves over the course of the year it can be helpful to remember that M13 is always on the westernmost side.

    As we close this edition, we leave you with this thought: Every star you gaze at in the night sky has incredible stories, mysteries, and histories to tell. As your eyes dance from one star’s point of light that left in 50 B.C. while Cleopatra sailed a moonlit Nile, to another star that winked at you from the 15th century as Leonardo da Vinci was painting The Last Supper … remember to seize the moment with awe and wonder.

    The renowned writer, Alan Moore, has suggested, “All we ever see of stars are their old photographs.” You think about that …

    Keep Looking UP! 

    Jeremy & Steve

    BDSO Staff



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