by neufer » Fri Jan 25, 2019 3:27 am
Nitpicker wrote: ↑Thu Jan 24, 2019 11:24 pm
Neufer, the 4th "m" can be found in "dimmmed". Mere minor mistake methinks.
- The "manger" M44 is the only truly "astronomical" object in the APOD
https://en.wikipedia.org/wiki/Beehive_Cluster wrote:
<<
Praesepe (Latin for "manger"), M44, NGC 2632, or Cr 189), is an open cluster in the constellation Cancer. Ancient Greeks and Romans saw this object as a manger from which two donkeys, the adjacent stars Asellus Borealis and Asellus Australis, are eating; these are the donkeys that Dionysos and Silenus rode into battle against the Titans. Aratus (c.260-270 BC) calls the cluster Achlus or "Little Mist" in his poem Phainomaina. Hipparchus (c.130 BC) refers to the cluster as Nephelion ("Little Cloud") in his star catalog. Ancient Chinese skywatchers saw this as a ghost or demon riding in a carriage and likened its appearance to a "cloud of pollen blown from willow catkins". It was also known by the somewhat less romantic name of Jishi qi, the "Exhalation of Piled-up Corpses". Claudius Ptolemy's Almagest includes Praesepe as one of seven "nebulae" (four of which are real), describing it as "The Nebulous Mass in the Breast (of Cancer)." It was among the first objects that Galileo studied with his telescope and was able to resolve it into 40 stars. Charles Messier added it to his famous catalog in 1769.
Age and proper motion coincide with those of the Hyades, suggesting they may share similar origins. Both clusters also contain red giants and white dwarfs, which represent later stages of stellar evolution, along with many main sequence stars. Age estimates of around 600 million years, equivalent to about 625 million years, for the Hyades. The diameter of the bright inner cluster core is about 7.0 parsecs.
Like many star clusters of all kinds, Praesepe has experienced mass segregation. This means that bright massive stars are concentrated in the cluster's core, while dimmer and less massive stars populate its halo (sometimes called the corona). Altogether, the cluster contains at least 1000 gravitationally bound stars, for a total mass of about 500-600 Solar masses. A recent survey counts 1010 members, of which 68% are M dwarfs, 30% are Sun-like stars of spectral classes F, G, and K, and about 2% are bright stars of spectral class A. Also present are five giant stars, four of which have spectral class K0 III and the fifth G0 III. So far, eleven white dwarfs have been identified, representing the final evolutionary phase of the cluster's most massive stars, which originally belonged to spectral type B. Brown dwarfs, however, are extremely rare in this cluster, probably because they have been lost by tidal stripping from the halo.>>
[quote=Nitpicker post_id=289265 time=1548372244 user_id=141578]
Neufer, the 4th "m" can be found in "dimmmed". Mere minor mistake methinks.[/quote]
[list]The "[b][color=#0000FF]manger[/color][/b]" M44 is the only truly "astronomical" object in the APOD :!: [/list]
[quote=" https://en.wikipedia.org/wiki/Beehive_Cluster"]
[float=left][img3="The donkeys Dionysos & Silenus rode into battle against the Titans"]https://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/Bf64580dfb9f301a0949e60106526057.1824x0_q100_watermark_watermark_opacity-10_watermark_position-6_watermark_text-Copyright_Intihuatana.jpg/800px-Bf64580dfb9f301a0949e60106526057.1824x0_q100_watermark_watermark_opacity-10_watermark_position-6_watermark_text-Copyright_Intihuatana.jpg[/img3][img3="Silenus on a donkey (c. 1500) by Piero di Cosimo"]https://upload.wikimedia.org/wikipedia/commons/e/e1/Piero_di_Cosimo_-_La_D%C3%A9couverte_du_miel.jpg[/img3][/float]
<<[b][color=#0000FF]Praesepe (Latin for "manger"), M44, NGC 2632, or Cr 189), is an open cluster in the constellation Cancer. Ancient Greeks and Romans saw this object as a manger from which two donkeys, the adjacent stars Asellus Borealis and Asellus Australis, are eating; these are the donkeys that Dionysos and Silenus rode into battle against the Titans.[/color][/b] Aratus (c.260-270 BC) calls the cluster Achlus or "Little Mist" in his poem Phainomaina. Hipparchus (c.130 BC) refers to the cluster as Nephelion ("Little Cloud") in his star catalog. Ancient Chinese skywatchers saw this as a ghost or demon riding in a carriage and likened its appearance to a "cloud of pollen blown from willow catkins". It was also known by the somewhat less romantic name of Jishi qi, the "Exhalation of Piled-up Corpses". Claudius Ptolemy's Almagest includes Praesepe as one of seven "nebulae" (four of which are real), describing it as "The Nebulous Mass in the Breast (of Cancer)." It was among the first objects that Galileo studied with his telescope and was able to resolve it into 40 stars. Charles Messier added it to his famous catalog in 1769.
Age and proper motion coincide with those of the Hyades, suggesting they may share similar origins. Both clusters also contain red giants and white dwarfs, which represent later stages of stellar evolution, along with many main sequence stars. Age estimates of around 600 million years, equivalent to about 625 million years, for the Hyades. The diameter of the bright inner cluster core is about 7.0 parsecs.
Like many star clusters of all kinds, Praesepe has experienced mass segregation. This means that bright massive stars are concentrated in the cluster's core, while dimmer and less massive stars populate its halo (sometimes called the corona). Altogether, the cluster contains at least 1000 gravitationally bound stars, for a total mass of about 500-600 Solar masses. A recent survey counts 1010 members, of which 68% are M dwarfs, 30% are Sun-like stars of spectral classes F, G, and K, and about 2% are bright stars of spectral class A. Also present are five giant stars, four of which have spectral class K0 III and the fifth G0 III. So far, eleven white dwarfs have been identified, representing the final evolutionary phase of the cluster's most massive stars, which originally belonged to spectral type B. Brown dwarfs, however, are extremely rare in this cluster, probably because they have been lost by tidal stripping from the halo.>>[/quote]