Skip to comments.Astronomers Find Two-Planet System in Beehive Cluster
Posted on 09/11/2018 10:21:47 AM PDT by ETL
The newly-discovered exoplanets, called EPIC 211964830b and c, are both mini-Neptunes gaseous planets smaller than our Solar Systems Uranus and Neptune.
The inner planet has a radius of around 2.3 times that of Earth, and the outer planet has a radius of 2.8 Earth radii. They orbit their parent star extremely closely, with periods of 5.8 and 19.7 days.
Designated EPIC 211964830, the star is an M2.5 dwarf, with a radius and a mass of about 47% that of the Sun.
It lies on the periphery of the central core of the Beehive Cluster (also known as Messier 44, NGC 2632 and Praesepe), a tightly packed collection of about 1,000 stars located approximately 550 light-years away in the constellation Cancer.
The Beehive stars were born out of the same cloud and have remained together for the past 650 million years.
EPIC 211964830b and c were discovered via the transit method used by NASAs Kepler space telescope, i.e. by detecting a small dip in the flux of the star, caused by the planet passing in front of it and blocking a small fraction of the stellar light.
The EPIC 211964830 system is currently the second known multi-transit system in open clusters younger than one billion years.
There are now several detected transiting planets in young open clusters and associations observed by K2, though EPIC 211964830 is one of only two multiple-planet systems, the other being K2-136, a three transiting-planet system in the Hyades open cluster, said Dr. Aaron Rizzuto from the University of Texas at Austin and colleagues.
(Excerpt) Read more at sci-news.com ...
But seriously, the "Beehive" (M44) is a compact cluster of stars which can easily be seen through a pair of binoculars, if you know where to look...
Looks something like this (below) through a telescope, or even binocs...
It is one of the nearest open clusters to Earth, containing a larger population of stars than other nearby bright open clusters. Under dark skies, the Beehive Cluster looks like a small nebulous object to the naked eye; as known since ancient times.
Classical astronomer Ptolemy described it as nebulous mass in the breast of Cancer, and it was among the first objects that Galileo studied with his telescope.
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.
Distance to M44 is often cited to be between 160 and 187 parsecs (520-610 light years)., but the revised Hipparcos parallaxes (2009) for Praesepe members and the latest infrared color-magnitude diagram favors an analogous distance of 182 pc.
There is better age estimates of around 600 million years old, equivalent to about 625 million years for the Hyades. The bright inner cluster cores diameter is about 7.0 parsecs (23 light years).
Observationally, the Beehive is easily visible to the naked eye as a small nebulous cloud when Cancer culminates in the early evening each year from February to May. At 1.5° across, the cluster easily fits within the field of view of binoculars or low powered small telescopes.
"Oh, Beehive!" -- Austin Powers
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Great post! THX!
*if you know where to look...*
I must say, in the past; I would have to arm myself w/ countless reference books when going out to the night sky. In of itself, that was very labor-intense. And was anyone’s guess of *where-to-look*.
My son got me a smart phone [ reluctant that I was, at first ...hey what was wrong with the little flip phone..it did everything I needed to do.] Well, with this new contraption, the nice star view apps are incredible .....just point and sha-zam! I’m loving it.
Also, the apps for bird, wildflower, rock/mineral and mushroom ID. Just amazing. I’m sold.
In 1609, Galileo first telescopically observed the Beehive and was able to resolve it into 40 stars.
Charles Messier added it to his famous catalog in 1769 after precisely measuring its position in the sky.
Along with the Orion Nebula and the Pleiades cluster, Messiers inclusion of the Beehive has been noted as curious, as most of Messiers objects were much fainter and more easily confused with comets.
Another possibility is that Messier simply wanted to have a larger catalog than his scientific rival Lacaille, whose 1755 catalog contained 42 objects, and so he added some well-known bright objects to boost his list.
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.
Hipparchus (c.130 BC) refers to the cluster as Nephelion (Little Cloud) in his star catalog.
Claudius Ptolemys Almagest includes the Beehive Cluster as one of seven nebulae (four of which are real), describing it as The Nebulous Mass in the Breast (of Cancer).
Aratus (c.260-270 BC) calls the cluster Achlus or Little Mist in his poem Phainomaina.
This perceived nebulous object is in the Ghost (Gui Xiu), the 23rd lunar mansion of ancient Chinese astrology. 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. It is also known simply as Jishi, cumulative corpses.
Morphology and composition
Like many star clusters of all kinds, Praesepe has experienced mass segregation. This means that bright massive stars are concentrated in the clusters core, while dimmer and less massive stars populate its halo (sometimes called the corona).
The clusters core radius is estimated at 3.5 parsecs (11.4 light years); its half-mass radius is about 3.9 parsecs (12.7 light years); and its tidal radius is about 12 parsecs (39 light years).
However, the tidal radius also includes many stars that are merely passing through and not bona fide cluster members.
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 high-probability 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 clusters 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.
The cluster has a visual brightness of magnitude 3.7. Its brightest stars are blue-white and of magnitude 6 to 6.5. 42 Cancri is a confirmed member.
Photo of comet C/2001 Q4 (NEAT) next to Messier 44
In September, 2012 two planets which orbit separate stars were discovered in the Beehive Cluster.
The finding was significant for being the first planets detected orbiting stars like Earths Sun that were situated in stellar clusters.
Planets had previously been detected in such clusters, but not orbiting stars like the Sun.
The planets have been designated Pr0201b and Pr0211b. The b at the end of their names indicates that the bodies are planets.
The discoveries are what have been termed Hot Jupiters, massive gas giants that, unlike the planet Jupiter, orbit very close to their parent stars.
The announcement describing the planetary finds, written by Sam Quinn as the lead author, was published in the Astrophysical Journal Letters.
Quinns team worked with David Latham of the Harvard-Smithsonian Center for Astrophysics, utilizing the Smithsonian Astrophysical Observatorys Fred Lawrence Whipple Observatory.
In 2016 additional observations concluded that in the Pr0211 system there are actually two planets, the second one being Pr0211-c.
So, he was messy-er than usual...............
I must say, in the past; I would have to arm myself w/ countless reference books when going out to the night sky. In of itself, that was very labor-intense. And was anyones guess of *where-to-look*.
I find that, the darker the sky, the harder it often is to find common objects. Because in a dark sky you are overwhelmed with bright objects and it's very hard, at least for me, to locate familar things. In fact, when out camping in dark upstate New York, I had a diffiult time finding the Big Dipper.
Yes, the apps are great. There are some that allow you to point the phone in any direction and have the constelations, planets, and just about anything else you want, display on the screen. You can even point it out the ground and have the objects on the other side of the Earth displayed on the screen.
There are bird watcher apps that identify bird calls and tell you what type of bird made the sound.
Yes, yes, and yes.
My big collection of Audubon nature books are now relics....dust catchers. :)
I saw those planets buzzing around that beehive.
“Ptolemy described it as nebulous mass in the breast of Cancer, and it was among the first objects that Galileo studied with his telescope.”
Good thing they detected the mass so early before it metastasized. This is why breast examinations are important!
I wouldn’t call it compact. In fact, it’s so spread out, you can see galaxies through it. :D
Of course, it is close to us, so, from far away, it may appear more compact.
Look up M11 for a REALLY compact open cluster
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