Astronomy

What will the mass of the new galaxy be?

What will the mass of the new galaxy be?


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When the Milky Way galaxy collides with the Andromeda galaxy, what will the mass and volume of the new galaxy be?


The mass will be slightly less than the combine masses of the 2 galaxies since some of the stars will be hurled away.

Since the disks of the galaxies are at an angle to each other, the volume would be (roughly) the volume of the 2 galaxies as they collide. Eventually, the volume will decrease (I'm guessing to between 60 to 70%) as the stars adapt to their new environment and the central massive black holes combine.


Samsung Galaxy Z Flip3 has reportedly entered mass production

Earlier this month, we heard the Samsung Galaxy Z Fold3 entered mass production, and now a new report by FrontPageTech claims the mass production of the Galaxy Z Flip3 has also kicked off.

The source also claims that Samsung has ordered the production of 50,000-70,000 units of Galaxy Z Fold3 and Galaxy Z Flip3 a day since it is aiming to produce a combined seven million units of both devices and wants to be ready in time for their launch.

Samsung Galaxy Z Flip3 in leaked promo

Samsung hasn't divulged anything about the Galaxy Z Fold3 or Z Flip3 yet, but the company is rumored to announce these devices on August 3, with the launch reportedly set for August 27.


These two phones are expected to fill the Galaxy Note series void in 2021

On top of that, a &lsquoGalaxy Note&rsquo handset won&rsquot be coming this year, so something needs to fill the void. That&rsquos where the Galaxy Z Fold 3 and Z Flip 3 are expected to step in, alongside the Galaxy S21 FE.

It remains to be seen how interested will people be in Samsung&rsquos new foldables. Samsung probably did some market research to prepare for the launch, but you can never know how will people react.

These two phones will be positioned as high-end devices, and they won&rsquot be cheap, but their price tags are expected to be considerably lower than those of their predecessors. Check out our Galaxy Z Fold 3 and Z Flip 3 previews for more information.


Milky Way’s Supermassive Black Hole is Spinning Slowly, Astronomers Say

Supermassive black holes are characterized by just two numbers: mass and spin, but have a critical influence on the formation and evolution of galaxies. The spin of Sagittarius A*, a 4-million-solar-mass black hole at the center of our Milky Way Galaxy, has been poorly constrained so far. In a new paper published in the Astrophysical Journal Letters, a team of U.S. astronomers placed an upper limit on the spin of Sagittarius A* based on the distribution of the S-stars in its vicinity.

Supermassive black holes at the cores of galaxies blast radiation and ultra-fast winds outward, as illustrated in this artist’s conception. Image credit: NASA / JPL-Caltech.

“Black holes release a huge amount of energy that removes gas from galaxies and therefore shapes their star formation history,” said Harvard University’s Professor Avi Loeb, co-author of the study.

“While scientists know that the mass of central black holes has a critical influence on their host galaxy, measuring the impact of their spin isn’t easy.”

“The effect of black hole spin on the orbits of nearby stars is subtle and difficult to measure directly.”

To get a better understanding of how Sagittarius A* has impacted formation and evolution of the Milky Way, Professor Loeb and his colleague, Dr. Giacomo Fragione from the Center for Interdisciplinary Exploration & Research in Astrophysics and Northwestern University, studied instead the stellar orbits and spatial distribution of the S-stars to place limits on the spin of the supermassive black hole.

“We concluded that the supermassive black hole in the center of our Galaxy is spinning slowly,” Dr. Fragione said.

“This can have major implications for the detectability of activity in the center of our galaxy and the future observations of the Event Horizon Telescope.”

This simulation shows the orbits of stars very close to Sagittarius A*, a supermassive black hole at the heart of the Milky Way. One of these stars, S2, orbits every 16 years and is passing very close to the black hole in May 2018. Image credit: ESO / L. Calçada / Spaceengine.org.

The S-stars appear to be organized into two preferred planes.

The authors showed that if Sagittarius A* had a significant spin, the preferred orbital planes of the stars at birth would become misaligned by the present time.

“For our study we used the recently-discovered S-stars to show that the spin of Sagittarius A* must be smaller than 10% of its maximal value, corresponding to a black hole spinning at the speed of light,” Professor Loeb said.

“Otherwise, the common orbital planes of these stars would not stay aligned during their lifetime, as seen today.”

The team’s results also point to another important detail about Sagittarius A*: it is unlikely to have a jet.

“Jets are thought to be powered by spinning black holes, which act as giant flywheels,” Professor Loeb said.

“Indeed there is no evidence of jet activity in Sagittarius A*,” Dr. Fragione added.

“Upcoming analysis of data from the Event Horizon Telescope will shed more light on this issue.”

Giacomo Fragione & Abraham Loeb. 2020. An Upper Limit on the Spin of SgrA* Based on Stellar Orbits in Its Vicinity. ApJL 901, L32 doi: 10.3847/2041-8213/abb9b4


Mass Effect 2's Galaxy Map Makes Interstellar Travel Interactive

The galaxy map in the first Mass Effect was little more than a glorified menu. Players simply move a cursor around to select star systems and planets. Mass Effect 2's galaxy map is not really all that different, but some added flair essentially turns it into a satisfactory mini-game. The cursor is replaced by a miniature version of the new Normandy SR-2 ship, which the player controls as it flies around the cosmos. Instead of zooming in and out, players fly to the edge of a star system in order for the perspective to widen, allowing other systems to become visible.

Although it's never truly difficult, some extra strategy is needed thanks to the addition of fuel. When traveling between systems, the Normandy burns through its fuel reserves, meaning players will have to spend credits to purchase fuel and plan their routes. Each cluster has a limited number of Mass Effect's iconic Mass Relays, meaning traveling large distances require the player to actually approach a Relay much like the Normandy actually would. The revamped galaxy map isn't as significant an upgrade as the combat in Mass Effect 2, but the added immersion from personally flying around the stars is a nice touch, even if it is overshadowed by a burdensome resource farming system.


We could get a glimpse at the Samsung Galaxy Watch 4 as soon as next week courtesy of MWC

2021 seems to be flying by much quicker than 2020. Mobile World Congress is already fast-approaching and Samsung is going the virtual route for its session. Earlier today, Samsung announced that it would be hosting a Samsung Galaxy session on June 28th. While not much information was shared, Samsung did state that it will be &ldquoshowcasing&rdquo how the Galaxy ecosystem can enrich your lifestyle. But the more interesting aspect of this event comes via the following:

&ldquoSamsung will also be unveiling its vision for the future of smartwatches at the event&hellip&rdquo

Ever since Google and Samsung announced the new version of Wear OS coming this Fall, we really haven&rsquot seen too much. We know that both Samsung and Fitbit&rsquos next smartwatches will be powered by this new collaboration. But there are still many questions that have been left unanswered. It&rsquos unlikely that Samsung will answer everything at this event, but what we could end up seeing is the Galaxy Watch 4 series.

Recent leaks suggest that Samsung&rsquos Galaxy Watch 4 lineup has gone into mass-production, meaning that an official release is coming soon. What will be interesting to see is how many new Galaxy Watch models are introduced. It&rsquos possible that Samsung just shows off the software, or we could end up seeing a new Galaxy Watch 4, and the highly-anticipated successor to the Galaxy Watch Active 2.

June 28th is just a week away, so we don&rsquot have too much longer to wait. Let us know what you think about this announcement, and whether Samsung will use this as an opportunity to introduce its new smartwatches, or if it will just be teasing the upcoming software changes.


Strong gravitational lenses are a rare and instructive type of astronomical object. Identification has long relied on serendipity, but different strategies—such as mixed spectroscopy of multiple galaxies along the line of sight, machine-learning algorithms, and citizen science—have been employed to identify these objects as new imaging surveys become available. We report on the comparison between spectroscopic, machine-learning, and citizen-science identification of galaxy–galaxy lens candidates from independently constructed lens catalogs in the common survey area of the equatorial fields of the Galaxy and Mass Assembly survey. In these, we have the opportunity to compare high completeness spectroscopic identifications against high-fidelity imaging from the Kilo Degree Survey used for both machine-learning and citizen-science lens searches. We find that the three methods—spectroscopy, machine learning, and citizen science—identify 47, 47, and 13 candidates, respectively, in the 180 square degrees surveyed. These identifications barely overlap, with only two identified by both citizen science and machine learning. We have traced this discrepancy to inherent differences in the selection functions of each of the three methods, either within their parent samples (i.e., citizen science focuses on low redshift) or inherent to the method (i.e., machine learning is limited by its training sample and prefers well-separated features, while spectroscopy requires sufficient flux from lensed features to lie within the fiber). These differences manifest as separate samples in estimated Einstein radius, lens stellar mass, and lens redshift. The combined sample implies a lens candidate sky density of ∼0.59 deg −2 and can inform the construction of a training set spanning a wider mass–redshift space. A combined approach and refinement of automated searches would result in a more complete sample of galaxy–galaxy lens candidates for future surveys.

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Galaxy and mass assembly : a comparison between galaxy⇓galaxy lens searches in KiDS/GAMA. / Knabel, Shawn Steele, Rebecca L. Holwerda, Benne W. Bridge, Joanna S. Jacques, Alice Hopkins, Andrew M. Bamford, Stephen P. Brown, Michael J.I. Brough, Sarah Kelvin, Lee Bilicki, Maciej Kielkopf, John.

Research output : Contribution to journal › Article › Research › peer-review


Unraveling Clyde's Spot

The storm that was Clyde's Spot has folded in on itself over the course of a year.
NASA / JPL-Caltech / SwRI / MSSS Image processing by Kevin M. Gill © CC BY­­

Clyde’s Spot, a distinctive white spot southeast of the Great Red Spot, received its nickname in honor of amateur astronomer Clyde Foster of Centurion, South Africa. He discovered it using his 14-inch Schmidt-Cassegrain telescope on May 31, 2020, two days before NASA's Juno mission was able to swing by for a closer look.

The initial white spot was a plume of methane-poor cloud material erupting above the top layers of the Jovian atmosphere. Later, the white spot faded and left behind a dark spot still visible in amateur scopes.

Now, a new image from Juno taken on April 15, 2021, shows that winds have stretched and pleated the spot into a folded filamentary region. These features are typically short-lived, disappearing quickly into the cloud decks, but due to its size this one might stick around for a while.

Read more about the latest image in NASA’s press release.


New Mass Estimate for Milky Way Galaxy: 1.54 Trillion Suns

The Milky Way contains an estimated 200 billion stars. But that’s just the bare tip of the iceberg — the Galaxy is surrounded by vast amounts of an unknown material called dark matter. Astronomers know it exists because, dynamically, the Milky Way would fly apart if dark matter didn’t keep a gravitational lid on things. Still, astronomers would like to have a precise measure of the Galaxy’s mass to better understand how the myriad galaxies throughout the Universe form and evolve. A team of researchers from ESO, the Space Telescope Science Institute, the Johns Hopkins University Center for Astrophysical Sciences and the University of Cambridge combined observations from the NASA/ESA Hubble Space Telescope and ESA’s Gaia satellite to study the motions of globular star clusters that orbit our Galaxy. The faster the clusters move under the entire Galaxy’s gravitational pull, the more massive it is. The team concluded the Milky Way has a mass of 1.54 trillion solar masses, most of it locked up in dark matter.

This artist’s impression shows a computer generated model of the Milky Way Galaxy and the accurate positions of the globular clusters used in this study surrounding it. Watkins et al used the measured velocities of these 44 globular clusters to determine the total mass of the Milky Way. Image credit: NASA / ESA / Hubble / L. Calçada.

The new mass estimate puts our Milky Way Galaxy on the beefier side, compared to other galaxies in the Universe.

The lightest galaxies are around a billion solar masses, while the heaviest are 30 trillion, or 30,000 times more massive. The Milky Way’s mass of 1.5 trillion solar masses is fairly normal for a galaxy of its brightness.

Previous estimates of the Milky Way’s mass ranged from 500 billion to 3 trillion solar masses. This huge uncertainty arose primarily from the different methods used for measuring the distribution of dark matter — which makes up about 90% of the mass of the Galaxy.

“We just can’t detect dark matter directly. That’s what leads to the present uncertainty in the Milky Way’s mass — you can’t measure accurately what you can’t see,” said Dr. Laura Watkins, an astronomer at ESO.

Given the elusive nature of the dark matter, the team had to use a clever method to weigh the Milky Way, which relied on measuring the velocities of globular clusters — dense star clusters that orbit the spiral disk of the Galaxy at great distances.

“The more massive a galaxy, the faster its clusters move under the pull of its gravity,” said Dr. N. Wyn Evans, from the University of Cambridge.

“Most previous measurements have found the speed at which a cluster is approaching or receding from Earth, that is the velocity along our line of sight. However, we were able to also measure the sideways motion of the clusters, from which the total velocity, and consequently the galactic mass, can be calculated.”

The scientists used Gaia’s second data release — which includes measurements of globular clusters as far as 65,000 light-years from Earth — as a basis for their study.

“Globular clusters extend out to a great distance, so they are considered the best tracers astronomers use to measure the mass of our Galaxy,” said Dr. Tony Sohn, an astronomer at the Space Telescope Science Institute.

Observations from Hubble allowed faint and distant globular clusters, as far as 130,000 light-years from Earth, to be added to the study. As Hubble has been observing some of these objects for a decade, it was possible to accurately track the velocities of these clusters as well.

“We were lucky to have such a great combination of data. By combining Gaia’s measurements of 34 globular clusters with measurements of 12 more distant clusters from Hubble, we could pin down the Milky Way’s mass in a way that would be impossible without these two space telescopes,” said Dr. Roeland P. van der Marel, also from the Space Telescope Science Institute.

Laura L. Watkins et al. 2019. Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions. ApJ, in press arXiv: 1804.11348


Free-Floating Planet-Mass Objects are Common in Galaxies

Using a technique called quasar microlensing, a team of astronomers at the University of Oklahoma has detected populations of free-floating planet-mass objects — exoplanets and/or primordial black holes — in two extragalactic systems: a lensing galaxy called Q J0158-4325 and the lensing galaxy cluster SDSS J1004+4112. These are only the second and third such detections in galaxies beyond our own.

X-ray image of the gravitational lens system SDSS J1004+4112 taken by NASA’s Chandra X-ray Observatory the central red extended emission is from the hot gas in the foreground lens galaxy cluster and the four blue point sources are the lensed images of the background quasar. Image credit: University of Oklahoma.

Q J0158-4325 is a galaxy-quasar lensing system, where a background quasar at a distance of 8.8 billion light-years is gravitationally lensed by a foreground galaxy at a distance of 3.6 billion light-years.

The lensing system SDSS J1004+4112 consists of a massive galaxy cluster at a distance of 6.3 billion light-years and a source quasar at a distance of 9.9 billion light-years.

Dr. Xinyu Dai from the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma and colleagues analyzed decade-long observations of these systems from NASA’s Chandra X-ray Observatory.

The evidence for planet-mass objects — with masses ranging from Moon to Jupiter mass — in the foreground galaxies was derived from the microlensing signals that appear as shifts in the X-ray emission line of the background quasars.

“These unbound objects are either free-floating planets or primordial black holes,” the researchers said.

“Free-floating planets were ejected or scattered during stellar/planetary formation. Primordial black holes are formed in the early phase of the Universe due to quantum fluctuation.”

“We are very excited about the detections in two news systems,” said Saloni Bhatiani, a Ph.D. student at the University of Oklahoma.

“We can consistently extract signals from planet mass objects in distant galaxies. This opens a new window in astrophysics.”

The team also found that planet-mass objects in Q J0158-4325 and SDSS J1004+4112 systems account for about 0.03% and 0.01% of the total mass of the system, respectively.

“The detection of planet-mass objects, either free-floating planets or primordial black holes, are extremely valuable for modeling of star/planet formation or the early Universe,” Dr. Dai said.

“Even without decomposing the two populations, our limit on the primordial black hole population are already a few orders of magnitude below previous limits in this mass range.”

“The results are of significant importance as they confirm that planet-mass objects are indeed universal in galaxies,” the scientists concluded.

Their work was published in the Astrophysical Journal.

Saloni Bhatiani et al. 2019. Confirmation of Planet-mass Objects in Extragalactic Systems. ApJ 885, 77 doi: 10.3847/1538-4357/ab46ac


What is the mass of the Milky Way?

A weird thing about astronomy is that one of the hardest things in the entire Universe to understand is the Milky Way galaxy.

It’s like knowing a lot about your neighborhood, the nearby city, and even your state, but not really knowing much about your own house.

To be fair, it’s like trying to understand your house but not being allowed to leave your closet. We’re inside the Milky Way, stuck about halfway out from the center, and everything we learn about it we learn from right here. The good news is we humans are really, really clever.

We invented telescopes! And we figured out how to observe the galaxy in different ways, and we learned that it’s a flat disk with spiral arms, surrounding a bulgy sphere of stars, surrounding a nucleus with a whopping great black hole in the center. There’s also a halo of stars surrounding the whole thing. We even have decent numbers on how big each component is, and even the mass for most of it.

Most… but not all. The disk, bulge, and nucleus are all made of what we call normal matter, atoms and electrons and protons and neutrons and stuff like that. Over the years we’ve been able to determine the mass of these components, mostly because we can see them and measure them.

But that halo is a problem. It has normal matter in it too, mostly in the form of stars, but the fact is the majority of it is made up of dark matter, stuff we can’t see, and can only infer.

The good news is that dark matter is still matter, and that means it has mass, and that means it has gravity. And that means (I may be getting too many “that means” deep here, but that’s the last one) we can determine its mass by how its gravity affects other stuff inside it.

And there is stuff inside the halo we can see, namely globular clusters. By combining data from the Hubble Space Telescope with new measurements using the phenomenal Gaia observatory, astronomers have now figured out the mass of the Milky Way halo: It’s 1.54 trillion times the mass of the Sun.

That’s a lot. It’s a big galaxy! But the fun is in how they did this.

The most current map of the Milky Way is shown in an artist’s representation. The Sun is directly below the galactic center, near the Orion Spur. The Scutum-Centaurus arms sweeps out to the right and above, going behind the center to the far side. The maser observed is almost directly opposite the Sun from the center in the S-C arm, 65,000 light years away. Credit: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)

An example: In our solar system, the overwhelmingly largest mass is the Sun. If you measure how fast a planet orbits the Sun, combined with its distance, you can determine the mass of the Sun (because the planet’s orbital speed is determined by the Sun’s gravity, which depends on its mass).

It’s more complicated for the galaxy, where the mass is more spread out, but the principle is the same. Isaac Newton showed that the gravity you feel from an object is the total mass between you and it. It doesn’t matter if the Sun is a teeny point or fills the orbit of the planet, the gravity felt by the planet is the same. Only the mass interior to the planet’s orbit matters.

So it goes for the Milky Way. If you want to get the mass of the Milky Way, you need to spot some very distant orbiting object, then measure its velocity around the galaxy to calculate all the galactic mass inside its orbit. This is pretty hard, because an object tens of thousands of light years away can be screaming through space, but it’s so far away that the apparent motion is small.

But: We have really good telescopes. And that motion can sometimes be measured.

The spectacular globular cluster NGC 1466. Credit: ESA/Hubble & NASA

Enter globular clusters. These are collections of hundreds of thousands or millions of stars held together by their own gravity, and they look like sparkling bees circling a hive. The Milky Way has at least 157 of these clusters, all orbiting the galactic center. Many are close by, and so not much use in getting the galaxy’s mass (the more distant, the more is enclosed by the orbit, so the better), but quite a few are very far away indeed.

The European Space Agency observatory Gaia was designed to look at over a billion stars in our galaxy, and determine their position, colors, and motion. It doesn’t discriminate it looks at every star it can, and many of those are in globulars. That means we have the motion across the sky of many of these clusters. Combined with careful measurements of their light to get their Doppler shift, that gives us a three-dimensional velocity of those clusters!

An animated image showing the motion of the globular cluster NGC 5466 (left) seen by Hubble Space Telescope over ten years. The close-up (right) shows the stars moving as a group with much more distant background galaxies appearing stationary. Credit: NASA, ESA, and S.T. Sohn and J. DePasquale (STScI)

The astronomers who did this work used 34 such clusters out of 75 measured by Gaia that fit what they needed, and they ranged in distance from 6,500 to almost 70,000 light years away from the galactic center. They also did this with clusters even farther away (out to nearly 130,000 light years) measured by Hubble. That added 16 more to their tally.

They were able to get everything they needed to then work out the mass of the galaxy. It’s still not easy, though! For example, the inner clusters seen by Gaia were more numerous, and so they got better statistics with them, but they’re not out far enough to get the total mass of the galaxy the galactic halo extends past them, and they can’t measure its mass with them. The Hubble clusters helped, but there were fewer of them, so the statistics were a bit dicier (although they got different total mass estimates using the two different cluster populations, the two numbers were within the statistical uncertainty of each other, which means that they’re indistinguishable statistically).

A simulation of the Milky Way galaxy surrounded by globular clsuters, using actual positional data. Credit: ESA/Hubble, NASA, L. Calçada, M.Kormesser

In the end they had to extrapolate out past these clusters given what we know about the shape and size of the halo, but again the numbers they got were consistent. To be fair, what they got was 1.54 trillion times the mass of the Sun, with an uncertainty of +0.75 trillion and -0.44 trillion… so it could be anything between 0.79 and 2.29 trillion.

This puts the Milky Way among the big galaxies in the Universe (which we knew). Many are larger, but most are much smaller.

So why do this? Does it matter what our total mass is?

Yes! For example, the mass of our galaxy is important in understanding the satellites that orbit it. There’s some argument over the behavior of the two biggest, the Large and Small Magellanic Clouds. Will they eventually collide? Are they truly orbiting us or just passing by? Our mass plays a part in that.

Illustration of a cosmic train wreck: The Milky Way/Andromeda galaxy collision, four billion years from now. Credit: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

Eventually the Andromeda galaxy will collide with us (in about 4.6 billion years). How that happens depends very much on our mass. The mass determination of the Milky Way also tells us about the structure of our galaxy, and even how it plays into the larger scale structure of the Universe. And it also tells us, simply enough, is our galaxy typical? Are we like other galaxies in some ways, different in others? We use our local surroundings as a template to understand what lies beyond — whether it’s our house in a neighborhood of hundreds of others or our galaxy among trillions.

It’s a bit parochial, sure, but it’s a good place to start. And, as we’ve found over and again, the Universe has a way of adjusting our initial outlook, diminishing our prejudices and strengthening our appreciation of diversity in the cosmos.