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New type variable star:  Blue Large-Amplitude Pulsator

 

 

BLAP- wikipedia

 

Arxiv pre-published paper (pdf) appears in Nature June 26, 2017 doi:10.1038/s41550-017-0166

 

Variable stars are very interesting because they give us some clues how stars tick in general and, what happens when one factor or another is a tad out of balance. The ways stars operate is a complex of six inter-related differential equations that define their, energy states, hydrostatic stability, energy diffusion and a number of other factors. When some stars go a bit wonky, we can infer some of these factors are a bit off. Variable stars of different types provide us with laboratory examples for long term study.

 

 

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Hey everyone, tomorrow, NASA will be ending the Cassini mission, and you can, tune in at 7 a.m. EDT, and watch them live as they witness the spacecraft's final moment. :) 

 

 

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Astronomers Observe Strange, Exotic Behavior at Titan's Polar Regions

November 21, 2017

Source Link

 

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A new study led by a University of Bristol earth scientist has shown that recently reported unexpected behavior on Titan, the largest moon of Saturn, and is the only moon in our solar system to have a substantial atmosphere, is due to its unique atmospheric chemistry. Titan's polar atmosphere recently experiences and unexpected and significant cooling, contrary to all model predictions and differing from the behavior of all other terrestrial planets in our solar system.

"This effect is so far unique in the solar system and is only possible because of Titan's exotic atmospheric chemistry, said Lead author Nick Teanby from the University of Bristol's School of Earth Sciences,. "A similar effect could also be occurring in many exoplanet atmospheres having implications for cloud formation and atmospheric dynamics."

 

Usually, the high altitude polar atmosphere in a planet's winter hemisphere is warm because of sinking air being compressed and heated - similar to what happens in a bicycle pump. Puzzlingly, Titan's atmospheric polar vortex (south polar vortex above) seems to be extremely cold instead.

Before its fiery demise in Saturn's atmosphere on September 15, the Cassini spacecraft obtained a long series of observations of Titan's polar atmosphere covering nearly half of Titan's 29.5 earth-year long year using the Composite Infrared Spectrometer (CIRS) instrument.

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The Cassini/CIRS observations showed that while the excepted polar hot spot did begin to develop at the start of winter in 2009, this soon developed into a cold spot in 2012, with temperatures as low as 120 K being observed until late 2015. Only in the most recent 2016 and 2017 observations has the expected hot-spot returned.

"For the Earth, Venus, and Mars, the main atmospheric cooling mechanism is infrared radiation emitted by the trace gas CO2 and because CO2 has a long atmospheric lifetime it is well mixed at all atmospheric levels and is hardly affected by atmospheric circulation," said Tenby. "However, on Titan, exotic photochemical reactions in the atmosphere produce hydrocarbons such as ethane and acetylene, and nitriles including hydrogen cyanide and cyanoacetylene, which provide the bulk of the cooling."

These gases are produced high in the atmosphere, so have a steep vertical gradient, meaning that their abundances can be significantly modified by even modest vertical atmospheric circulations. Therefore, winter polar subsidence led to massive enrichments of these radiatively active gases over the southern winter pole.

Researchers used the temperature and gas abundances measured with Cassini, coupled with a numerical radiative balance model of heating and cool rates, to show that trace gas enrichment was large enough to cause significant cooling and extremely cold atmospheric temperatures.

This explains earlier observations of strange hydrogen cyanide ice clouds that were observed over the pole in 2014 with Cassini's cameras.

The Daily Galaxy via University of Bristol  

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NASA VIDEO: "Supermoon Trilogy!" --Tonight's Moon Kicks Off a Series of Three Supermoons on December 3, 2017, January 1, 2018, and January 31, 2018 (WATCH Video)

December 03, 2017

Source Link: Daily Galaxy

 
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Mark your calendars: on December 3, 2017, January 1, 2018, and January 31, 2018. A supermoon is a Moon that is full when it is also at or near its closest point in its orbit around Earth. Since the Moon’s orbit is elliptical, one side (apogee) is about 30,000 miles (50,000 km) farther from Earth than the other (perigee). Nearby perigee full Moons appear about 14% bigger and 30% brighter than full Moons that occur near apogee in the Moon's orbit.

“The supermoons are a great opportunity for people to start looking at the Moon, not just that once but every chance they have!” says Noah Petro, a research scientist from NASA’s Goddard Space Flight Center.

 

 

It’s hard for our eyes to distinguish these small changes in size when the Moon is high amidst the vastness of the night sky. But any time you catch a full Moon as it rises or sets, while it’s suspended low on the horizon beaming through the silhouettes of trees or buildings, its apparent size might make you do a double-take. You almost feel as though you could reach out, grab the glowing orb, and drop it into your coffee cup. Even more so if it’s a supermoon.

If you can only catch one episode of the supermoon trilogy, catch the third one. It will be extra special.

First of all, the January 31st supermoon will feature a total lunar eclipse, with totality viewable from western North America across the pacific to Eastern Asia. The Moon’s orbit around our planet is tilted so it usually falls above or below the shadow of the Earth. About twice each year, a full Moon lines up perfectly with the Earth and Sun such that Earth’s shadow totally blocks the Sun’s light, which would normally reflect off the Moon.

“The lunar eclipse on January 31 will be visible during moonset. Folks in the Eastern United States, where the eclipse will be partial, will have to get up in the morning to see it,” notes Petro. “But it’s another great chance to watch the Moon.”

The Moon will lose its brightness and take on an eerie, fainter-than-normal glow from the scant sunlight that makes its way through Earth’s atmosphere. Often cast in a reddish hue because of the way the atmosphere bends the light, totally eclipsed Moons are sometimes called ‘blood Moons.’

“We’re seeing all of the Earth’s sunrises and sunsets at that moment reflected from the surface of the Moon,” says Sarah Noble, a Program Scientist at NASA headquarters.

The January 31st supermoon will also be the second full Moon of the month. Some people call the second full Moon in a month a Blue Moon, that makes it a super ‘blue Moon.’ Blue Moons happen every two and a half years, on average. With the total eclipse, it’ll be a royal spectacle indeed: a ‘super blue blood’ Moon.

Sometimes the celestial rhythms sync up just right to wow us. Heed your calendar reminders. On the three dates marked, step out into the moonset or moonrise and look up for a trilogy of sky watching treats!

The Daily Galaxy via Moon/NASA

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NASA Releases Astounding Video Of The Lagoon Nebula To Celebrate Hubble’s Birthday

The Huffington Post has a neat article about this which contains the video NASA put together which is quite vivid.

 

https://www.huffingtonpost.com/entry/nasa-lagoon-nebula-hubble-video_us_5adbcceae4b075b631e65bce

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Wow! Thanks DD.

Those videos are spectacular

Yay for the Hubble telescope.

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Star Creation --"May Not Be the Same Everywhere in the Milky Way"

April 30, 2018

 

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The mass distribution of young stars may not be the same everywhere in our Galaxy, contrary to what is currently assumed. If this turns out to be the case, the scientific community will be forced to re-examine its calculations about star formation and, eventually, any estimates that depend on the number of massive stars, such as the chemical enrichment of the interstellar medium, and the numbers of black holes and supernovas.

In space, hidden behind the dusty veils of nebulae, clouds of gas clump together and collapse, forming the structures from which stars are born: star-forming cores. These cluster together, accumulate matter and fragment, eventually giving rise to a cluster of young stars of various masses, whose distribution was described by Edwin Salpeter as an astrophysical law in 1955.

 

Astronomers had already noticed that the ratio of massive objects to non-massive objects was the same in clusters of star-forming cores as in clusters of newly-formed stars. This suggested that the mass distribution of stars at birth, known as the IMF1, was simply the result of the mass distribution of the cores from which they formed, known as the CMF2.

However, this conclusion resulted from the study of the molecular clouds closest to our Solar System, which are not very dense and therefore not very representative of the diversity of such clouds in the Galaxy. Is the relationship between the CMF and the IMF universal? What do we observe when we look at denser, more distant clouds?

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These were the questions asked by researchers at the Grenoble Institute of Planetology and Astrophysics and the Astrophysics, Instrumentation and Modelling Laboratory, when they started to observe the active star-formation region W43-MM1, whose structure is far more typical of molecular clouds in our Galaxy than those observed previously. Thanks to the unprecedented sensitivity and spatial resolution of the ALMA antenna array in Chile, the researchers were able to establish a statistically robust core distribution over an unmatched range of masses, from solar-type stars to stars 100 times more massive. To their surprise, the distribution did not obey Salpeter's 1955 law.

It turned out that, in the W43-MM1 cloud, there was an overabundance of massive cores, while less massive cores were under-represented. These findings call into question not only the relationship between the CMF and the IMF, but even the supposedly universal nature of the IMF.

The teams will continue their work with ALMA within a consortium of around forty researchers. Their aim is to study 15 regions similar to W43-MM1 in order to compare their CMFs and ascertain whether the characteristics of this cloud can be generalized.

NASA's Wide-field Infrared Survey Explorer, or WISE, captured the image at the top of the page of a star-forming cloud of dust and gas located in the constellation of Monoceros. The nebula, commonly referred to as Sh2-284, is relatively isolated at the very end of an outer spiral arm of our Milky Way galaxy. In the night sky, it's located in the opposite direction from the center of the Milky Way.

Perhaps the most interesting features in Sh2-284 are what astronomer call "elephant trunks." Elephant trunks are monstrous pillars of dense gas and dust. The most famous examples of are the "Pillars of Creation," found in an iconic image of the Eagle nebula from NASA's Hubble Space Telescope. In this WISE image, the trunks are seen as small columns of gas stretching towards the center of the void in Sh2-284, like little green fingers with yellow fingernails. The most notable one can be seen on the right side of the void at about the 3 o'clock position. It appears as a closed hand with a finger pointing towards the center of the void. That elephant trunk is about 7 light-years long.

Deep inside Sh2-284 resides an open star cluster, called Dolidze 25, which is emitting vast amounts of radiation in all directions, along with stellar winds. These stellar winds and radiation are clearing out a cavern inside the surrounding gas and dust, creating the void seen in the center. The bright green wall surrounding the cavern shows how far out the gas has been eroded

However, some sections of the original gas cloud were much denser than others, and they were able to resist the erosive power of the radiation and stellar winds. These pockets of dense gas remained and protected the gas "downwind" from them, leaving behind the elephant trunks. These pillars can also be thought of as rising like stalagmites from the cavern walls.

The Daily Galaxy via Grenoble Institute of Planetology and Astrophysics (CNRS/Université Grenoble Alpes)

 

 

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Not really a huge surprise of a discovery. Stars form differently in different regions. This is known from observation. Different types of stars form under different conditions. 

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Baby planet found!

 

The first "baby planet" detected so far, though the article comments that a baby planet boom is imminent....

 

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