APOD: The Small Cloud of Magellan (2021 Jan 05)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 4164
Joined: Fri Dec 04, 2009 3:27 am

APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by APOD Robot » Tue Jan 05, 2021 5:05 am

Image The Small Cloud of Magellan

Explanation: What is the Small Magellanic Cloud? It has turned out to be a galaxy. People who have wondered about this little fuzzy patch in the southern sky included Portuguese navigator Ferdinand Magellan and his crew, who had plenty of time to study the unfamiliar night sky of the south during the first circumnavigation of planet Earth in the early 1500s. As a result, two celestial wonders easily visible for southern hemisphere skygazers are now known in Western culture as the Clouds of Magellan. Within the past 100 years, research has shown that these cosmic clouds are dwarf irregular galaxies, satellites of our larger spiral Milky Way Galaxy. The Small Magellanic Cloud actually spans 15,000 light-years or so and contains several hundred million stars. About 210,000 light-years away in the constellation of the Tucan (Tucana), it is more distant than other known Milky Way satellite galaxies, including the Sagittarius Dwarf galaxy and the Large Magellanic Cloud. This sharp image also includes the foreground globular star cluster 47 Tucanae on the right.

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Ann
4725 Å
Posts: 11067
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by Ann » Tue Jan 05, 2021 6:35 am

Fascinating image by José Mtanous! Let's compare it with a picture of the Small Magellanic Cloud by Jason Jennings.

The Small Magellanic Cloud Jason Jennings.png
The Small Magellanic Cloud. Photo: Jason Jennings.





















The two images are not oriented exactly the same way, but a comparison between them helps clarify the shape and also colors of the Small Magellanic Cloud, I think.

But there is more to see. I'm going to "steal" alter-ego's crop (and identification of Sigma Octantis) of the APOD of January 1, 2021, by Petr Horalek and Josef Kujal, which highlights a possibly visual interaction between the Small Magellanic Cloud and its big bully of a neighbour, the Large Magellanic Cloud:

Possible Magellanic Stream.png

























This is what you can see in my clumsy annotation of the picture at right:

1) 47 Tuc, the second brightest globular cluster of the Milky Way.

2) NGC 362, another Milky Way globular.

3) A stream of stars being pulled from the Small Magellanic Cloud in the direction of the Large Magellanic Cloud?


If the stream of stars from the SMC towards the LMC that I think I can see actually exists, then it seems to start "opposite" bright globular cluster 47 Tuc. If you check out José Mtanous' and Jason Jennings's pictures of the Small Magellanic Cloud (and 47 Tuc), you can see that there is a clustering of pink or red emission nebulas on the "other" side of the main body of the Small Magellanic Cloud.

This group of emission nebulas might be the beginning of the stellar stream that I think I can see reaching from the SMC towards the LMC.

What do the rest of you think?

Ann
You do not have the required permissions to view the files attached to this post.
Color Commentator

heehaw

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by heehaw » Tue Jan 05, 2021 10:50 am

What a help for astronomers it is, that the SMC's motion has been such that 47 Tuc is not directly in front of it, messing up its image for us on Earth. Whew!

User avatar
orin stepanek
Plutopian
Posts: 5934
Joined: Wed Jul 27, 2005 3:41 pm
Location: Nebraska

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by orin stepanek » Tue Jan 05, 2021 1:32 pm

Ever wonder what Magellan thought he was looking at when he saw these clouds? :shock:

SMC_Mtanous_960.jpg

What a beauty this baby galaxy is! 8-) the globular clusters are
pretty neat also!
You do not have the required permissions to view the files attached to this post.
Orin

Smile today; tomorrow's another day!

User avatar
neufer
Vacationer at Tralfamadore
Posts: 17749
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by neufer » Tue Jan 05, 2021 3:43 pm

https://en.wikipedia.org/wiki/Ferdinand_Magellan wrote: <<Born around 1480 into a family of minor Portuguese nobility, Ferdinand Magellan became a skilled sailor and naval officer and was in service of the Portuguese crown in Asia. After King Manuel I of Portugal refused to support his plan to reach India by a new route, by sailing around the southern end of the South American continent, he was eventually selected by King Charles I of Spain to search for a westward route to the Maluku Islands (the "Spice Islands").

Five vessel fleet left Spain on 20 September 1519, sailing west across the Atlantic toward South America. In December, they made landfall at Rio de Janeiro. From there, they sailed south along the coast, searching for a way through or around the continent. After three months of searching (including a false start in the estuary of Río de la Plata), weather conditions forced the fleet to stop their search to wait out the winter. They found a sheltered natural harbor at the port of Saint Julian, and remained there for five months. Shortly after landing at St. Julian, there was a mutiny attempt led by the Spanish captains Juan de Cartagena, Gaspar de Quesada and Luis de Mendoza. Magellan barely managed to quell the mutiny, despite at one point losing control of three of his five ships to the mutineers. Mendoza was killed during the conflict, and Magellan sentenced Quesada and Cartagena to being beheaded and marooned, respectively. Lower-level conspirators were made to do hard labor in chains over the winter, but later freed.

During the winter, one of the fleet's ships, the Santiago, was lost in a storm while surveying nearby waters, though no men were killed. Following the winter, the fleet resumed their search for a passage to the Pacific in October 1520. Three days later, they found a bay which eventually led them to a strait, now known as the Strait of Magellan, which allowed them passage through to the Pacific. While exploring the strait, one of the remaining four ships, the San Antonio, deserted the fleet, returning east to Spain. The fleet reached the Pacific by the end of November 1520. Based on the incomplete understanding of world geography at the time, Magellan expected a short journey to Asia, perhaps taking as little as three or four days. In fact, the Pacific crossing took three months and twenty days. The long journey exhausted their supply of food and water, and around 30 men died, mostly of scurvy. Magellan himself remained healthy, perhaps because of his personal supply of preserved quince.

On 6 March 1521, the exhausted fleet made landfall at the island of Guam and were met by native Chamorro people who came aboard the ships and took items such as rigging, knives, and a ship's boat. The Chamorro people may have thought they were participating in a trade exchange (as they had already given the fleet some supplies), but the crew interpreted their actions as theft. Magellan sent a raiding party ashore to retaliate, killing several Chamorro men, burning their houses, and recovering the 'stolen' goods. On 16 March, the fleet reached the Philippines, where they would remain for a month and a half. Magellan befriended local leaders on the island of Limasawa, and on 31 March, held the first Mass in the Philippines, planting a cross on the island's highest hill. Magellan set about converting the locals to Christianity. Magellan had converted as many as 2,200 locals to Christianity, including Rajah Humabon of Cebu and most leaders of the islands around Cebu. However, Lapulapu, the leader of Mactan, resisted conversion. In order to gain the trust of Rajah Humabon, Magellan sailed to Mactan with a small force on the morning of 27 April 1521. During the resulting battle against Lapulapu's troops, Magellan was struck by a bamboo spear, and later surrounded and finished off with other weapons.

Antonio Pigafetta and Ginés de Mafra provided written documents of the events culminating in Magellan's death:
  • When morning came forty-nine of us leaped into the water up to our thighs, and walked through water for more than two crossbow flights before we could reach the shore. The boats could not approach nearer because of certain rocks in the water. The other eleven men remained behind to guard the boats. When we reached land, those men had formed in three divisions to the number of more than one thousand five hundred persons. When they saw us, they charged down upon us with exceeding loud cries ... The musketeers and crossbowmen shot from a distance for about a half-hour, but uselessly; for the shots only passed through the shields ... Recognizing the captain, so many turned upon him that they knocked his helmet off his head twice ... An Indian hurled a bamboo spear into the captain's face, but the latter immediately killed him with his lance, which he left in the Indian's body. Then, trying to lay hand on sword, he could draw it out but halfway, because he had been wounded in the arm with a bamboo spear. When the natives saw that, they all hurled themselves upon him. One of them wounded him on the left leg with a large cutlass, which resembles a scimitar, only being larger. That caused the captain to fall face downward, when immediately they rushed upon him with iron and bamboo spears and with their cutlasses, until they killed our mirror, our light, our comfort, and our true guide. — Antonio Pigafetta[33]:173–177
Nothing of Magellan's body survived, that afternoon the grieving rajah-king, hoping to recover his remains, offered Mactan's victorious chief a handsome ransom of copper and iron for them but Datu Lapulapu refused. He intended to keep the body as a war trophy. Since Magellan's wife and child died in Seville before any member of the expedition could return to Spain, it seemed that every evidence of Ferdinand Magellan's existence had vanished from the earth.>>
Art Neuendorffer

User avatar
johnnydeep
Science Officer
Posts: 360
Joined: Sun Feb 20, 2011 8:57 pm

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by johnnydeep » Tue Jan 05, 2021 5:42 pm

Ann wrote:
Tue Jan 05, 2021 6:35 am
If the stream of stars from the SMC towards the LMC that I think I can see actually exists, then it seems to start "opposite" bright globular cluster 47 Tuc. If you check out José Mtanous' and Jason Jennings's pictures of the Small Magellanic Cloud (and 47 Tuc), you can see that there is a clustering of pink or red emission nebulas on the "other" side of the main body of the Small Magellanic Cloud.

This group of emission nebulas might be the beginning of the stellar stream that I think I can see reaching from the SMC towards the LMC.

What do the rest of you think?

Ann
Seems plausible. From various searching, apparently the LMC and SMC orbit each other with a period of 900 million years, and are both responsible for the much larger Magellanic Stream, so your conjectured smaller stream from the SMC to the LMC is either exactly that or perhaps just a "filament" of the Magellanic Stream.

From https://apod.nasa.gov/apod/ap980826.html:
"To Boldly Go......Beyond The Fields We Know."

heehaw

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by heehaw » Tue Jan 05, 2021 11:46 pm

We're so lucky to have LMC and SMC dancing before us, and also having Andromeda, splayed beautifully before our very eyes (and also, easily visible to the naked eye!). Imagine if we had found that we were in the middle of some mess of colliding galaxies! What a shemozzle!

User avatar
rj rl
Ensign
Posts: 52
Joined: Tue Jul 23, 2013 3:37 am

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by rj rl » Wed Jan 06, 2021 10:08 am

The APOD says SMC is 15kly across, wikipedia says 7kly, who's right?

User avatar
Ann
4725 Å
Posts: 11067
Joined: Sat May 29, 2010 5:33 am

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by Ann » Wed Jan 06, 2021 10:50 am

rj rl wrote:
Wed Jan 06, 2021 10:08 am
The APOD says SMC is 15kly across, wikipedia says 7kly, who's right?
I would guess the APOD is wrong. The diameter of the SMC is, indeed, 7,000 light-years according to Wikipedia.

The LMC, by contrast, is 14,000 ly according to Wikipedia. Maybe the APOD has mixed them up somehow?

Ann
Color Commentator

VictorBorun
Ensign
Posts: 73
Joined: Fri Oct 16, 2020 10:25 pm

Re: APOD: The Small Cloud of Magellan (2021 Jan 05)

Post by VictorBorun » Thu Jan 07, 2021 11:56 pm

How to guess the size of a distorted barred disk galaxy when the dark part is elusive?
For now we have light matter sizes: SMC 7 kly, LMC 14 kly, with 75 kly between these binary system galaxies.
Then again, some suppose SMC is in fact teared in two, with 30 kly between foreground and background shreds.

As our Sun orbits the Milky Way's center the GAIA and like would get some parallaxes.
Or maybe we get better on dark matter and gas halos.

What is a galaxy boundary by the way? A surface of maximal gravity?