Astronomy Archives

March 22, 2021March 22, 2021 by Matt Williams

Rocks and Other Features at Perseverance’s Landing Site are Getting Navajo Names

On Feb. 18th, 2021, after spending six months in transit, the Perseverance rover landed in the Jezero Crater on Mars. By March 4th, it began driving short distances and calibrating its instruments in preparation for all the science operations it will conduct. Most recently, Perseverance began studying its first scientific target, a rock that has been named “Máaz” – the Navajo word for “Mars.”

March 22, 2021March 23, 2021 by David Dickinson

New Binocular Nova Cas 2021 Flares in Cassiopeia

A ‘new star’ erupted into visibility over the past weekend, and continues to brighten.

It began, as all modern astronomical alerts seem to, with one tweet, then two. Early on the morning of Friday, March 19^th, we started seeing word that a nova was spotted in the constellation of Cassiopeia the Queen, near its border with Cepheus. At the time, the nova was at magnitude +10 ‘with a bullet,’ and still brightening. A formal notice came that same night from the American Association of Variable Star Observers (AAVSO) with Alert Notice 735 on the discovery of the first nova in Cassiopeia for 2021, Nova Cassiopeiae 2021, or N Cas 2021.

March 19, 2021March 19, 2021 by Matthew Cimone

An All-Sky X-Ray Survey Finds the Biggest Supernova Remnant Ever Seen

Composite Image of radio and x-ray observations of the Hoinga Supernova Remnant Credit: eROSITA/MPE (X-ray), CHIPASS/SPASS/N. Hurley-Walker, ICRAR-Curtin (Radio)

Our sky is missing supernovas. Stars live for millions or billions of years. But given the sheer number of stars in the Milky Way, we should still expect these cataclysmic stellar deaths every 30-50 years. Few of those explosions will be within naked-eye-range of Earth. Nova is from the Latin meaning “new”. Over the last 2000 years, humans have seen about seven “new” stars appear in the sky – some bright enough to be seen during the day – until they faded after the initial explosion. While we haven’t seen a new star appear in the sky for over 400 years, we can see the aftermath with telescopes – supernova remnants (SNRs) – the hot expanding gases of stellar explosions. SNRs are visible up to a 150,000 years before fading into the Galaxy. So, doing the math, there should be about 1200 visible SNRs in our sky but we’ve only managed to find about 300. That was until “Hoinga” was recently discovered. Named after the hometown of first author Scientist Werner Becker, whose research team found the SNR using the eROSITA All-Sky X-ray survey, Hoinga is one of the largest SNRs ever seen.

Composite of the X-ray (pink) and radio (blue) image of Hoinga. The X-rays discovered by eROSITA are emitted by the hot debris of the exploded progenitor star. Radio antennae on Earth detect radiation emission from electrons in the outer shell of the supernova
Credit: eROSITA/MPE (X-ray), CHIPASS/SPASS/N. Hurley-Walker, ICRAR-Curtin (Radio)

March 18, 2021March 19, 2021 by Matt Williams

Oumuamua Isn’t an Alien Probe, Because Aliens can Learn Everything They Need About us With Telescopes

Artist’s impression of the interstellar object, `Oumuamua, experiencing outgassing as it leaves our Solar System. Credit: ESA/Hubble, NASA, ESO, M. Kornmesser

In the Fall of 2017, the first known interstellar object passed through the Solar System, triggering a revolution in astronomy. Because of the amonolous nature of the object, astronomers from all over the world were at a loss to explain what it was. Neither comet, nor asteroid, nor any other conventional object appeared to fit the bill, leading to all kinds of “exotic” explanations.

A particularly exotic explanation was offered by Harvard Professor Avi Loeb and his former postdoc (Dr. Shmuel Bialy), who hypothesized that ‘Oumuamua could have been an extraterrestrial lightsail. Whereas most rebuttal papers questioned the evidence presented, a new study by astrophysicist and UCLA emeritus professor Ben Zuckerman questioned something else: why would an extraterrestrial civilization want to send a probe our way?

March 18, 2021March 18, 2021 by David Dickinson

Tracking Satellites Through GEOSat Eclipse Season

You can spot ‘GEOSat’ satellites in far-flung orbits… if you know exactly where and when to look.

Watch the sky long enough, and you’re bound to see one.

Seasoned observers are very familiar with seeing satellites in low Earth orbit, as these modern artificial sky apparitions lit by sunlight grace the dawn or dusk sky. Occasionally, you might even see a flare from a passing satellite, as a reflective solar panel catches the last rays of sunlight passing overhead just right…

March 16, 2021March 16, 2021 by Ralph Crewe

Do Supermassive Black Holes Come From Supermassive Stars?

Colors reveal complex interactions of oxygen abundance driving a supernova in a 55,000 solar mass star.

The gargantuan supermassive black holes at the center of seemingly every galaxy are among the most fascinating and extreme objects known to modern astronomy and cosmology. With masses well in excess of millions, and sometimes billions that of our Sun, it is nearly impossible to comprehend the extraordinary size of these celestial leviathans. One of the great mysteries of modern astrophysics is answering how such enormous objects got started. In a press release published on March 10th, researchers propose that the origins of supermassive black holes may lie with long since extinct, first-generation stars with masses far above the most massive stars in the modern Universe. Not only do they propose such giants existed, but also they suggest that they’ve found a way to detect a particular subset of these stars. This breakthrough is thanks to our old friend, Einstein’s General Theory of Relativity.

March 15, 2021March 15, 2021 by Brian Koberlein

Wormholes Could Allow Travel Across the Universe, as Long as Your Spacecraft is Microscopic

Artist rendering of a wormhole connecting two galaxies. Credit: Davide and Paolo Salucci

In my last post, I talked about the idea of warp drive and whether it might one day be possible. Today I’ll talk about another faster-than-light trick: wormholes.

March 14, 2021March 14, 2021 by Matt Williams

There Should be About 7 Interstellar Objects Passing Through the Inner Solar System Every Year

A Hubble image of Comet 2IBorisov from October 2019. Image Credit: By NASA, ESA, and D. Jewitt (UCLA) - https://imgsrc.hubblesite.org/hvi/uploads/image_file/image_attachment/31897/STSCI-H-p1953a-f-1106x1106.png, Public Domain, https://commons.wikimedia.org/w/index.php?curid=83146132

In October 19th, 2017, the first interstellar object ever detected flew past Earth on its way out of the Solar System. Less than two years later, a second object was detected, an easily-identified interstellar comet designated as 2I/Borisov. The appearance of these two objects verified earlier theoretical work that concluded that interstellar objects (ISOs) regularly enter our Solar System.

The question of how often this happens has been the subject of considerable research since then. According to a new study led by researchers from the Initiative for Interstellar Studies (i4is), roughly 7 ISOs enter our Solar System every year and follow predictable orbits while they are here. This research could allow us to send a spacecraft to rendezvous with one of these objects in the near future.

March 12, 2021March 12, 2021 by Matt Williams

The Giant Magellan Telescope’s 6th Mirror has Just Been Cast. One More to Go

By 2029, the Giant Magellan Telescope (GMT) in northern Chile will begin collecting its first light from the cosmos. As part of a new class of next-generation instruments known as “extremely large telescopes” (ELTs), the GMT will combine the power of sophisticated primary mirrors, flexible secondary mirrors, adaptive optics (AOs), and spectrometers to see further and with greater detail than any optical telescopes that came before.

At the heart of the telescope are seven monolithic mirror segments, each measuring 8.4 m (27.6 ft) in diameter, which will give it the resolving power of a 24.5 m (80.4 ft) primary mirror. According to recent statements from the GMT Organization (GMTO), the University of Arizona’s Richard F. Caris Mirror Lab began casting the sixth and seventh segments for the telescope’s primary mirror (which will take the next four years to complete).

March 12, 2021March 9, 2021 by Paul M. Sutter

Measuring the Temperatures of Red Giants is Actually Pretty Tricky

Artist's impression of a red giant star. If the star is in a binary pair, what happens to its sibling? Credit:NASA/ Walt Feimer

Red giant stars are, well, red and giant. But astronomers have always had difficulty estimating their temperatures, due to their complex and turbulent atmospheres. Without an accurate gauge of their temperatures, it’s difficult to tell when they will end their lives in gigantic supernova explosions. Now a team of astronomers have developed a more effective technique for taking the temperature of red giants, based on the amount of iron in the stars.