Cosmology - Blog Posts
Read a paper whose research was of the theoretical nature! It appears thermal physics is Very interesting and I must learn about the generalized uncertainty principle and instantons.
Ooo now I can briefly introduce something! So, the Earth isn’t expanding and infinitely large. Flatness, for the universe, means that parallel lines remain parallel, the angles of a triangle add up to 180, etc etc.
Cosmologists also came up with cosmic inflation, to explain that any curvature was smoothed out through exponential growth. For the universe to be as flat as it is now, it would have to have been even FLATTER in the past! Think about a spinning top… if there is an imperfection in the setup, it will fall over. Since we don’t observe deviations in the flatness of the universe, it follows that like the top must have been incredibly perfectly set up, the extremely early universe must have been incredibly flat!
Note that a period of inflation helps solve some other problems, but that’s beyond the scope of this post (see the “relic problem,” “horizon problem,” and “structure problem”).
the Earth is locally flat. since flatness is a local property, it follows that the Earth is flat.
Feeling stressed? Imagine being squeezed into a point smaller than an atom! 😱 That's what happens at the heart of a black hole. Swipe ➡️ through this post to learn how these cosmic wonders are formed! 🌌✨
This is Rosette Nebula — which got its nickname from its close resemblance to a flower in bloom. It's the Perseus Arm of the galaxy, about a 130 light-years-wide nebula that hosts a club of more than 10,000 young stars.
Image Credit: CalTech/Palomar
Simulation Credit: MarsWalkers
Our sun is entering into a sleepy state of inactivity— a recurring phenomenon known as Solar Minimum.
A period of minimal solar activity, during which the surface solar movement diminishes, resulting in a trough in solar eruptions and coronal mass ejections (CME) activities. Though it is a period of (relative) calm for the otherwise seething ball of energy, it doesn't hold any consequence(s) for us, as Earthlings. Sun, as we know it, will remain the same.
The Enigma of Elune & the Elements
The goddess Elune is known by many names across cultures and even planets; such as Mother Moon, White Lady, Night Warrior, Mu’sha, etc. She has a wide reach across various spheres of cosmology, and her domain seems to at least encompass the arcane, the natural, the astral, the spiritual, and in many unexpected connections–the elemental. It could be that, as Elune is considered a life goddess with some connections to the afterlife, she may have pseudo-elemental expressions of power because they are partially intertwined with spirit. This might explain the physical tangibility, and yet silvery-blue coloring that often manifests within elements of Elunian origin. The following is a collection of curiosities in which the goddess’s influence presents itself in such forms.
Water
The first, most notable link between Elune and the elements would be her thematic ties and manifestations of power within water. An iconic and central piece of Kaldorei culture is the moonwell: it is often the focal point of temples, and a place of respite in the wilds which restores mana, cleanses impurities, blesses armaments, purifies corruption, and even banishes maddened elementals. Dave Kosak, in his development of the Warcraft cosmology, describes the combination of spirit and water as one of the main vehicles for healing; both of which are linked to the outer ring of Nature. An old myth of the Kaldorei Empire described Elune sleeping inside of the Well of Eternity during the day, and rising into the sky as the moon each night. Today, moonwells are established through local wild spirits granting their blessing, a combination of natural and lunar magick, as well as a droplet of eternal waters from another purified well. All of these spheres together (spirit, water, nature, and arcane) encompass the very essence of Elune's moonwells.
Tears of Elune are one of the most recurring themes in relation to the goddess - seen in the pillar of creation, and lesser items scattered throughout the world. We do not know for certain how these tears form; however, there is an implication that they are a manifestation of Elune’s emotions, whether crying tears of sadness, or of joy. These remnants from the goddess seem to possess a myriad of properties the beholder can make use of: the Tearstone of Elune legendary ring has a chance to cast an additional regrowth on targets, Tears of the Goddess from the Hyjal raid slow the player’s falling speed, and Elune’s Tear can ease the symptoms of illness. Mu’sha’s Tears are gathered at the base of a waterfall in Highmountain, which are guarded by fiercely protective water elementals, to eventually be used during a ritual that allows us to witness the events of the War of the Ancients. Interestingly, these specific tears are said to “flow of their own accord,” entirely ignoring the rushing rapids that would normally carry away physical objects or other water currents; which may lend to the notion that Elune’s elemental manifestations are partially comprised of spirit. The Sisters’ Tear, born of Elune and the Winter Queen’s combined power, is yet another example of renewal and lifegiving springing forth from the goddess’s sorrow: which resulted in the growth of the World Tree, Amirdrassil.
Elune is described as having partial influence over the tides, a power that she shares with Neptulon, as evidenced by the Tablet of the Balancing Tides: "The whispers of Elune and Neptulon play on the tides, their words etched in stone are a tribute to the balance of their powers." There is additionally a brief archaeology quest in Throne of the Tides we can pick up from an ancient fountain. Delving into our historical knowledge from reading a Highborne Scroll fragment, we discover that the purpose of this fountain is to confer a blessing called “Waters of Elune,” which specifically increases our damage against the naga while inside the domain of Neptulon, further strengthening the alliance between the two. The goddess also seems to feel a responsibility, or at least have an interest, in purifying maddened water elementals. We see this demonstrated in Moon Priestess Tharill’s questline in Darkshore, who asks us to use a relic called the Orb of Elune; which has the power to soothe and permanently banish these beings back to their plane. This ultimately protects the elementals from the cycle of being resummoned, further manipulated, and driven to madness. As the orb was carried by Tharill just south of Auberdine, this may have been a prized and sacred relic of the town used in banishing angered elementals from the coasts of Darkshore. It would not be the first or only sacred artifact kept here, as Auberdine also once housed the Eye of Elune.
Elune’s aqueous blessings were also a crucial part in the battle of the Molten Front within the Firelands. It seems that somehow, the nature of Elune’s blessings can circumvent traditional interactions between elements. The very existence of a moonwell, or any body of water for that matter inside the scorching plane of Ragnaros, would reasonably evaporate. The fact that this one is able to withstand the extreme heat of the Firelands speaks to a high resistance, if not complete immunity, to the effects of fire. Ayla Shadowstorm explains that the moonwell’s waters can indeed provide some protection against flame, as well as bless the expedition’s food stores. Once the well is filled, small bushes and trees begin to sprout nearby that eventually bear eternal fruits which can be used indefinitely while inside the Molten Front. While it is unclear what role Elune plays in the existence of wisps, these spiritual beings are considered “perfectly suited” to banishing elementals (similar to the goddess herself) as seen in this quest where the wisps aid us in closing the portals of fire elementals.
In the tauren mythos of Eyes of the Earthmother, Mu’sha as she is called, is said to "dance with the waters of the tides," "flow out of shadow’s reach like water," and bind injuries with the powers of water and wind.
Fire
The satyr camp of Sargeron in Desolace, known colloquially as the Palace/Sanctuary/Cathedral/Temple of Elune, reveals an interesting relic that links Elune to the element of fire. Unearthed from the ruins of the temple here, there is a tall runestone monument known as the Ancient Vortex Runestone. It is said that the ancient Kaldorei “revered the gems created by this mystical object, claiming that they were gifts from the goddess herself. It was believed that they were weapons capable of delivering them from any enemy.” As we progress in the questline, we are able to make use of these gemstones, which summon forth a giant firestorm, whose power is strengthened “either through sustained worship of Elune, or charged by spiritual energies of the fallen.”
During the war against the scourge in Northrend, the settlement of Stars’ Rest converted their moonwell to house the liquid fire of Elune, an offshoot of traditional moonwell waters. The very nature of this substance seems to be an oxymoron, combining two opposing elements of fire and water into one. However, if we consider again Dave Kosak’s notes on the life-giving essence of spirit; he links spirit and water with healing, and spirit and fire with holy powers of retribution. The fact that Elune’s liquid fire encompasses spirit, water, and fire then becomes clearer in the goal of this quest: to pour it over the corpses of scourge-blighted animals and cleanse them of their corruption. This essentially combines Kosak’s ideas through healing their bodies and demonstrating a retribution against the unnatural state of undeath. This may also speak to the circumventing of traditional elemental interactions, as the liquid fire of this moonwell (assumedly) prevents the vessel from freezing over.
In Darkshore, a moonkin named Aroom requests our aid in cleansing their corrupted brethren. They task adventurers with slaying a ghost of their kind who wields a relic called Elune’s Torch. After retrieving the torch, Aroom creates a ritual bonfire with the flames from this item, which allows the corrupted moonkin to find rest in the afterlife and “return to Elune, finally.” It could be that these flames of Elune act as spiritual purification, essentially burning away the madness or corruption clouding the moonkin’s minds. The fact that they are able to find peace (after this torch is used to create a larger and more substantial bonfire) may indicate that Elune’s flame acts as a beacon of guidance for the dead, which allows them to more easily move on from the physical plane.
There is also a unique type of silvery blue and purple fire found in Kaldorei settlements, old ruins, and temples that is vastly different from traditional orange, red, and yellow flame. The most intriguing are the braziers found in Azsuna and Tel’anor of Suramar, a necropolis assumed to be abandoned by its groundskeepers. Yet, all throughout the area there are braziers still burning brightly as if just fed with wooden kindling. It is unclear how they are sustained, but this may reinforce the idea that it is not true fire in the typical understanding of the element, but a mixture of fire and spirit together.
Earth
While Elune seems to be more distant from the element of earth than its counterparts, it is interesting to consider her manifestations that appear in traditionally earthbound mediums.
The first is Elunite Ore - ore in general being a naturally occurring rock or stone with valuable minerals inside. Elunite is described as being a fine material to work with, and directly blessed by Elune herself. The nature of Elunite is unclear; we do not know if it is an ore that is blessed by the goddess after its formation, or if Elune has a hand in its creation within the earth. It is not a usable material by miners and blacksmiths, perhaps implying that crafting with Elunite is a rare technique known only to select artisans, Elanaria (the questgiver) being one of them. It could also be that the privilege of shaping Elunite requires performing an act in defense of the goddess’s domain; as Elanaria tells us that in order to make our weapon, we must slay a satyr corrupting a moonwell, and defeat the shade of Elura who has cursed herself to guard her shipment of Elunite ore beneath the waves for all eternity.
The next earthly manifestations of Elune come in the form of gemstones, which traditionally find their origin from “deep in the earth, brought to the surface by explosions of molten rock.” Some are also “crystallized slowly from hot fluids and gases, formed from liquids filtered into cracks and pockets in rock, formed when rocks were heated and pressurized by earth movements, and recombined to form new, different minerals.” It is unclear whether Elunian gems are created similarly, or whether they are perhaps crystallized magic of some kind. As mentioned in the section of Fire, the Ancient Vortex Runestone was said to produce gemstones that Elune bequeathed to her followers here to defend themselves with. Additionally in Winterspring, there is an old altar that once housed a precious relic called the Gem of Elune that allowed direct communication with Her, and through which she “channeled her infinite wisdom.” In Outland, there are also rare jewels called Stars of Elune that can be prospected from various native ores, and dropped by random enemies.
In the Legend of Elun’Ahir, the goddess is said to be one who gifted Eonar with a branch of G’Hanir, a Mother Tree that once existed inside the Emerald Dream. After Aman’thul ripped it from the earth, its roots still grew below ground, nourished by Eonar’s tears: “Below ground, the roots fed upon the tears of Eonar and grew strong. The war was long, but in the end, the titans claimed victory. And Eonar was pleased, knowing Elune's legacy would endure. It is said that much later, as the world entered a new age, mysterious guardians arrived who dedicated their lives to protecting the roots.”
There are also several flowers said to be touched by Elune. One grows in the shadows of Duskwood, called Elune's Grace, which glows with the intensity of the moon and attracts wolves to its location. The flowers required to craft various Blossom Crowns during the Lunar Festival supposedly hold a strong connection to the goddess as well, imbued with a "solemn peace," "Elune's might," "happiness," and "great fortune." Myrael Lunarbloom also wields a staff whose flowers bloom during this time of year, greatly empowered by a moonwell pilgrimage ritual. She even says, "Flowers flourish under Elune's light. She was always known to cherish them."
Air
The Eyes of the Earthmother tells of the goddess’s early mythological origins, and her sphere of influence includes both water and wind. It seems that Elune (Mu’sha in this story) works with the wind most commonly as a means to communicate, and to deliver thoughts, words, and feelings. While the Earthmother slumbers, Mu’sha’s powers were said to be diminished, and she could no longer harness the winds' power since they “whipped up in storms and blizzards.” She is also described as “sharing secrets” with the winds, later sending upon them a plea to the Earthmother. Eventually, the Earthmother is able to find her way back to Mu’sha, because “the winds pulled at her hands, and guided her swiftly to find her Sun and Moon.” After the Earthmother’s sacrifice, Mu’sha pays homage to her by carrying her last words on the breeze for the tauren to hear, as well as setting the winds across the tides so that her voice could always be followed. Mu’sha’s favored weaponry was also said to be the bow and arrow, the efficacy of which is highly dependent on wind flow. Her movements are described as “quick as the wind,” and when her brother, An’she, is severely wounded, she calls upon these forces in an attempt to heal his injury: “Mu'sha tried to bind her brother's wound with water and wind, but no matter what she did, he continued to bleed.”
An in-game connection between Elune and the realm of wind is from a side quest in Darkshore just following the events of the Cataclysm. Sentinel Selarin, at the Auberdine refugee camp, leads the endeavor to eradicate the Twilight’s Hammer wind elementals overtaking the ruins of the town. An arduous process that requires an intricate solution, as the Twilight’s Hammer can continuously resummon the elementals at their command. In order to put an end to this, the elementals must be “slain;” after which we take their bracers, thought to be physical bindings anchoring them to this plane. The way to stop this cycle once and for all is to place the bracers into a moonwell. This act is said to not only prevent the elementals from being resummoned, but completely destroying the bracers as well. While this is not said to “soothe” them like the Orb of Elune, this seems to accomplish the same goal of freeing the enslaved elementals and the remaining Kaldorei.
While not a manifestation of elemental power per se, Elune’s influence upon the winds is also demonstrated in priestesses who channel her power through song; as well as relics like the Chimes of the Moon in Tel’anor: “The Sisters say that Elune sings a song, notes pure and beautiful. The Chime does not ring often, but when it does it is the same note as the one She is singing.” During the War of the Ancients especially, the strengthening magic utilized by the Sisters was invaluable to the war effort, notably through battle chants: “Then, another welcome surprise—chanting came from the center of the advance. The Sisterhood of Elune, resplendent in their battle armor, strengthened the fighters further. Day might have held precedence at the moment, but the priestesses’ rhythmic singing literally fed the nocturnal warriors. It was as if the moon herself suddenly hung over the host.” (Demon Soul, Ch. 8)
While we may think of this magic as under the strict purview of the elementals, it has been said that "Elune’s true nature is not fully understood," and the breadth of her power and influence may be even more vast and complex than initial impressions.
We went to the local observatory tonight but when we got there, there was a HUGE line of people. Whoops. It’s was still really pretty and we got to see an amazing view of the stars.
These are my attempts to take a picture of the sky with my phone but they didn’t turn out very well. I don’t even remember what I was trying to photograph. Next time, I’ll try to bring an actual camera.
I think the brightest one in the left picture might be Jupiter???? lol 🥲
Thor's Helmet taken by Chris DeCosta and Martin Pugh on February 28 2019
NGC 2359, also referred to as Thor's Helmet, is an emission nebula in the constellation Canis Major. At the heart of this nebula is a Wolf-Rayet star WR7, which is in this phase briefly before a supernova occurs.
The bubble appearance of this nebula is due to the strong stellar winds coming from WR7. These winds contribute to forming a complex structure, with a huge mass of ionized material. The high energy radiation coming from the star ionizes hydrogen to produce red light and doubly ionizes oxygen to produce blue light.
The gas absorbs and then reemits this light, leading to the name of "emission nebula".
Star Trails taken by Rob on February 24 2024
Star trails are photographs taken over long exposures, where the rotation of the Earth causes the stars to appear as arcs in the sky instead of points. The Earth rotates around its axis every 23 hours and 56 minutes.
Typically, star trails are focused on Polaris in the northern hemisphere, but I found this photo unique because it opted for a different composition. It also really highlights how dense the sky is with stars.
It begs the question, why isn't the sky infinitely bright with infinite stars? This is actually the observation that helped cosmologists find theories for the age of the universe. For a young universe, not enough time has passed for the light from incredibly distant stars to reach us, leading to the dark sky we see when we look up at night.
Dolphin Head Nebula taken by Ben Brown on February 23 2024
The Dolphin Head Nebula, Sh 2-308, is an emission nebula caused by the Wolf-Rayet star EZ Canis Majoris. WR stars have completed fusion of hydrogen and are now fusing heavier elements such as helium and carbon. They have unique emission spectrums for this reason, with no hydrogen emission lines.
The temperature of WR stars is much higher than typical stars, reaching 20,000 K to 210,000 K. WR stars are some of the most luminous stars due to their high temperatures, but most of their output is in the ultraviolet spectrum, meaning we can't see it with the naked eye.
This UV radiation ionizes the gas around it, leading to the emission nebula you can see in the photograph.
my new favorite poem ✨
The Large Magellanic Cloud taken by Rory Broesder on Februrary 18 2023
The LMC is a satellite galaxy to the Milky Way, set to collide in 2.4 billion years. It is an easily observable object from the southern hemisphere and is the fourth brightest galaxy in the local group. Within this galaxy is the Tarantula Nebula, a very active star forming region.
It was once a barred spiral galaxy before it was disrupted through tidal interactions with the Milky Way galaxy and Small Magellanic Cloud. In fact, there is a bridge of hot gas showing the connection between the LMC and SMC which is also an active star forming region.
The LMC is one of around sixty other satellite galaxies orbiting the Milky Way.
i went to the local library to pick up some books today :) i'm literally so dumb because i was in the wrong row for the nonfiction section (looking for spacefarers) and i did not even stop to question why all the books around me were on the culinary arts.
i heard the master of djinn is a really good book and would be good for people that liked arcane. IF I MAKE IT THROUGH THE BOOK, maybe i'll write a review. hopefully i can because it looks really interesting...
i have a lot of random stuff to do these next two days since i wasn't productive for the first three days of break :(
study for computer science midterm
calculus unit 4 problem sets
magnetostatics FRQ
read literature for research project
update astrophysics notes
work on cosmology simulation
Flame Nebula taken by Hubble Space Telescope
This nebula is an emission nebula— a star forming region in the Orion constellation. The nebula is filled with young stars; however, dense gas obscures the majority of the cluster.
In this cluster, it contains at least one O-type star that emits light, exciting the gas around it.
O-type stars are huge blue stars that are easily seen from Earth, even from farther distances. They have extremely high surface temperatures, causing them to lose energy at a much faster rate than other stars. These massive stars live for much smaller lifetimes, before resulting in supernova explosions and eventually forming a neutron star or black hole.
Vela Supernova Remnant taken on February 6 2021 by jeff2011 on Astrobin
The supernova remnant resides within the Vela constellation, having exploded over ten thousand years ago. It is the closes supernova remnant to Earth. Observational data from this remnant provided proof that supernova’s can produce neutron stars.
Supernovas occur at the end of a star’s life. Stars with mass over eight solar masses finish burning the hydrogen in their core and become a red supergiant. Successive fusion then occurs until the core contains iron. Fusion can no longer occur at iron since it is not energetically favorable. Gravity then takes over leading to a supernova explosion— expelling a huge amount of stellar material.
Neutron stars can form as a result of this, as protons and electrons collide to combine into neutrons. The neutron stars are stable by neutron degeneracy pressure. This pressure is caused the Pauli Exclusion principal which prevents neutrons from having the same positions.
The Soul Nebula taken by Kurt Wallberg on Februrary 1 2024
This image depicts The Soul Nebula (IC 1848) on the left and Westhout 5 (IC 1848) on the right. Westhout 5 is part of the bigger Soul Nebula. It’s an emission nebula— consisting of the star forming regions with ionized hydrogen gas and dark nebula. Dark nebulas are when the stellar medium is so dense that the light from objects behind it cannot pass through.
As you can see in the image, there are cavities in the gas. These were carved out by stars due to radiation and stellar winds. There is a theory of triggered star formation, which describes that these cavities compress the gas around it to trigger star formation. Images such as these have been used to help prove this theory, showing that the closer the star is to the cavity, the younger it is.
International Space Station transit of the Moon taken by Quinn Groessl on January 31 2023.
The ISS orbits the Earth at a typical velocity of 28000 km/h (very fast) and at a typical altitude of 400 km. Gravitational forces keep the ISS in constant freefall, but with the forward velocity of the ISS, the overall distance to Earth and velocity stays pretty much the same.
These transits are pretty infrequent. The angle of the moon from the orbital plane can vary over time, and any small changes in the ISS orbit can have major effects on its path. In the sky, they are both fairly small objects, leading to smaller probabilities as well.
An important factor that allows these events to occur is that the ISS is traveling much faster relative to our perspective on Earth compared to the moon. The ISS orbits the Earth around 16 times a day, while the moon takes around a month (27.3 days).
You can see the video of it at this link. It's incredible how precise astronomers have to be with how short of a timespan there is to record this.
NGC 2403 taken by John C. Yu on January 30 2024
NGC 2403 is a intermediate spiral galaxy. There are typically two types of spiral galaxies: barred and regular spirals. This galaxy falls between the two, denoted as SAB.
The bar in spiral galaxies forms due to gravitational instability. However, this bar can help with star formation as it funnels material to the center of the galaxy.
Interactions with neighboring galaxies or having greater instability can lead to a greater bar shape in the galaxy. However, dark matter halos also play a big role in having the opposite effect, often preventing the bar from forming. These combined factors lead to the median shape of this galaxy.
Intermediate spiral galaxies can eventually evolve into either regular spiral galaxies or barred spiral galaxies, but we won't be there to see the final form of NGC 2403.
Rosette Nebula taken by Suzanne Beers on January 29 2024
The Rosette Nebula is part of the Milky Way Galaxy and is located 5,000 light years away from Earth. The Rosette Nebula is an emission nebula (not to be confused with planetary nebula).
These kinds of nebula are formed around massive, hot stars, whose ultraviolet radiation ionizes the surrounding gas. The excited atoms in the nebula also emit radiation, causing the nebula's glow.
The Rosette Nebula is also home to star forming regions, as observed by the Chandra X-ray Observatory. These are especially concentrated in the bottom of the nebula, although it is difficult to see in this image. Note that this photo uses the Hubble color palette.
Messier 66 taken by Hubble Space Telescope on January 28 2021
In this picture, it showcases the star forming regions of the galaxies, which can be seen in red. Star forming regions are vulnerable to disturbances, which can cause the gas in the interstellar medium to collapse into dense clumps of material. These are called protostars.
During the formation of these protostars, gravitational energy is converted into thermal energy. If there is enough thermal energy produced, it is enough to spark nuclear fusion. The star then joins the main sequence.
Due to nature of the star forming regions, it often yields the creation of star clusters, since many stars are being created in close proximity. Large stars especially can emit radiation and produce stellar winds, which pushes the star away from these regions.
Comet C/2022 E3 (ZTF) taken by Auvo Korpi on January 27 2023.
During the formation of the sun, there was a protoplanetary disk (cloud of debris and gas) that orbited around it. The farthest parts of this disk were far from the heat emitted, and cooled down. The cold material clumped with frozen gasses and water, creating icy rocks.
These rocks orbit far away from the sun in huge elliptical orbits, in the Kuiper belt and Oort cloud. At one point, the icy rocks get closer to the sun. The ice is heated and releases dust, known as the comet’s trail.
Comet ZTF was first discovered in March 2022, but came closest to Earth in a long time in January of 2023. At first, the comet was believed to be an asteroid, but when it got closer to the sun, it was observed to have its signature green glow.
The green comes from the diatomic carbon, which is part of the comet’s atmosphere. As it got closer to the sun, the molecules became excited and radiate green light. This is also why the green color doesn’t extend to the tail, instead it is happening in the comet’s nucleus.
I remember going out with my telescope around this time to view the comet. At that point I think it was just above the Taurus constellation, and I had a lot of trouble angling the lens to point that high up.
I don’t remember being able to see the tail, but just with the naked eye, I could see the comet’s light. I can’t believe it’s already been two years since then. Time really flies.
NGC 1316 taken by Hubble Space Telescope on January 26 2021
NGC 1316 is an elliptical galaxy formed by the collisions of multiple galaxies near the constellation Forax in the southern hemisphere. What makes this galaxy unique is the dark lanes of dust visible around the galaxy. These are indicative that they galaxies NGC 1316 was formed by were spiral galaxies.
What helped scientists determine that this galaxy was created due to a "recent" collision where different types of images taken of NGC 1316. Hubble's images helped to reveal huge collisional shells and a small number of globular clusters. Collisional shells are formed from debris of the parent galaxy, which under the effects of gravity and tidal forces. These tails last for a long time, before eventually being reabsorbed into the progenitor (object of origin). Globular clusters are a group of stars bound by gravity.
These two events were indicative of a merger that occurred within the past couple billion years.
Sirius A and B taken on 13th December 2005 by Hubble Space Telescope
Sirius A is well known for being the brightest star in the night sky and a part of the constellation Canis Major. However, its binary partner, Sirius B was only discovered in 1862.
Ever since the creation of Newton’s law of universal gravitation, star mechanics became not only descriptive, but also predictive. Sirius A’s path across the night sky was unexpected. It wasn’t a straight line, but rather oscillated across its path. This caused many scientists to suspect that Sirius A had a binary partner.
Sirius B was first observed by Alvan Clark, who was testing a new telescope at the time. This was later on confirmed by other telescopes.
Sirius B is a white dwarf, while Sirius A is a main sequence star, meaning it is much larger and much brighter. 1000x brighter than Sirius B, in fact.
In the photo, Sirius A is in the center (although there are some effects due to the instruments) and Sirius B can be seen in the lower left.