Starship Asterisk*

Kevin Reardon wrote:
This is not INTEGRAL/IBIS, but rather the Interferometric BIdimensional Spectrometer, a ground-based imaging spectrometer based on dual Fabry-Perot interferometers in series which allows us to take very narrowband images sequentially through a variety of spectral lines (like H-alpha 6563 or Ca II 8542) in the visible and near-infrared. At the wavelength of the Calcium line in the APOD image, the passband is 0.045 Angstrom (and 0.025 Å at H-alpha). This very narrow passband is one reason the structures are so well resolved. Some dated web pages about the instrument are available here: http://www.arcetri.astro.it/science/sol ... /ibis.html

http://en.wikipedia.org/wiki/Calcium#H_and_K_lines wrote:

[url=http://www.astrosurf.com/~buil/lhires_ir/obs_us.htm]H and K lines of ionized Calcium[/url]

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<<Visible spectra of many stars, including the Sun, exhibit strong absorption lines of singly ionized calcium. Prominent among these are the H-line at 3968.5 Å and the K line at 3933.7 Å of singly ionized calcium, or Ca II. For the Sun and stars with low temperatures, the prominence of the H and K lines can be an indication of strong magnetic activity in the chromosphere. Measurement of periodic variations of these active regions can also be used to deduce the rotation periods of these stars.>>

http://www.astrosurf.com/~buil/lhires_ir/obs_us.htm wrote:

Ca II 8542

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Temperature of the objects drops while going from the top down

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INFRARED OBSERVATIONS WITH LHIRES III

<<We presents some images of 2D spectra of the sun light
(daylight in cloudy weather) in the infrared domain.
Spectrograph LHIRES III is simply held with the hand.
The grating used is the 1200 lines/mm.

The selected area of the spectrum contain the infrared triplet of ionized calcium.
The interest of the choice:

• - the presence of the calcium lines, but also the beginning of the Pashen sequence of hydrogen (the infrared equivalent of the Balmer series of in the visible spectrum, which ends with the famous Ha line),
  
  - an atmospheric window, quasi free from telluric water vapor lines,
  
  - the presence of many emission lines produced by the internal lamp of LHIRES III for a simple and precise spectral calibration,
  
  - one seen it, the CMOS of the Canon detector become a black and white sensor in this part of the spectrum.

Joe wrote:
Reminds me of sea anemonae.

http://www.nhdfl.org/about-forests-and-lands/bureaus/natural-heritage-bureau/photo-index/eelgrass-bed.aspx wrote:

Eelgrass bed beneath the waters of New Hampshire's Great Bay

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<<Eelgrass beds are a type of subtidal natural community that occur exclusively below mean low tide, although upper reaches may be briefly exposed during the lowest spring tides. Common eel-grass (Zostera marina) is the dominant rooted vegetation. This continually submerged aquatic community performs important ecological functions including supporting eelgrass and fish populations, providing refuge for fish and invertebrates that retreat from exposed intertidal flats and estuarine marshes at low tide, and serving as a spawning and nursery area for numerous species of aquatic animals.>>

http://www.selfgrowth.com/articles/What_Does_Calcium_Have_to_do_With_The_Sun.html wrote:
What Does Calcium Have To do With The Sun? by Erleen Tilton

<<Calcium is the most abundant mineral in the body with more than 99% present in the bones and teeth. Calcium is also important in the activity of many enzymes, contraction of muscles, release of neurotransmitters, regulation of heartbeat, and clotting of the blood. Calcium deficiencies can results in bone deformities, growth retardations in children, osteomalacia (softening of the bones), and osteoporosis in adults.

Most of us have been brainwashed through textbooks and advertisements to believe that our best and highest sources of calcium are from milk products. However, most have not learned that there are many great sources of calcium from SEAWEEDS, leafy greens, legumes, fruits, vegetables, and more. Most people probably eat enough foods that provide ample sources of calcium, yet most people are very deficient in calcium. Why? Because it’s not just getting the calcium that is important, it’s absorbing the calcium that is key! Absorbing calcium depends on a very important vitamin – Vitamin D.

Our best source of natural Vitamin D actually comes from the Sun. And since many of us have been roped into the myth that the sun is our enemy and we need to avoid the sunshine unless we are slathered with sunscreen, we block the possibility of getting our most important source of Vitamin D which leaves us deficient in calcium.

The sun is really our friend, and we need to get at least 20-30 minutes of sunshine daily between the hours of 10:00 am and 4:00 pm – without sunscreen! Before or after those times, we don’t get enough Vitamin D absorption.>>

DavidLeodis wrote:It's a great image but it would seem that there is an error in its explanation. In that it states "Spicules line the above frame of solar active region 11092 that crossed the Sun last month" (thus October) but in the information brought up through the "Pictured above" link it states the image was acquired on August 3 2010.

DavidLeodis wrote:I also have a query about IBIS. The information brought up through the link in the credit was the same as that brought up through the "Pictured above" link which did not state what IBIS is and seems to have no link to an IBIS website. From a search I found there is an IBIS which is the "INTEGRAL imager, IBIS (Imager on-Board the INTEGRAL Satellite)" which is surveying the X-ray and gamma ray sky, so I wonder if that actually is the IBIS in the APOD? I would be grateful if someone could please let me know what IBIS in the APOD definitely is. Thanks.

http://en.wikipedia.org/wiki/Hairy_ball_theorem wrote:
<<The hairy ball theorem of algebraic topology states that there is no nonvanishing continuous tangent vector field on an even-dimensional n-sphere.

This is famously stated as "you can't comb a hairy ball flat without creating a cowlick",
or sometimes, "you can't comb the hair on a coconut". It was first proved in 1912 by Brouwer.

A failed attempt to comb a hairy 3-ball (2-sphere),
leaving an uncomfortable tuft at each pole........ A hairy doughnut (2-torus) OTOH is quite easily combable.

A curious meteorological application of this theorem involves considering the wind as a vector defined at every point continuously over the surface of a planet with an atmosphere. In the case where there is at least some wind, the Hairy Ball Theorem dictates that at all times there must be at least one point on a planet with no wind at all and therefore a tuft. In a physical sense, this zero-wind point will be the eye of a cyclone or anticyclone. (Like the swirled hairs on the tennis ball, the wind will spiral around this zero-wind point - under our assumptions it cannot flow into or out of the point.) In brief, then, the Hairy Ball Theorem dictates that, given at least some wind on Earth, there must at all times be a cyclone somewhere.>>

http://en.wikipedia.org/wiki/Luitzen_Egbertus_Jan_Brouwer wrote:

<<Luitzen Egbertus Jan Brouwer (February 27, 1881 – December 2, 1966), usually cited as L. E. J. Brouwer but known to his friends as Bertus, was a Dutch mathematician and philosopher. In 1905, at the age of 24, Brouwer expressed his philosophy of life in a short tract Life, Art and Mysticism described by Davis as "drenched in romantic pessimism." Brouwer's thesis advisor refused to accept his Chapter II " 'as it stands, ... all interwoven with some kind of pessimism and mystical attitude to life which is not mathematics, nor has anything to do with the foundations of mathematics' "

About his last years, Davis (2002) remarks:

• "...he felt more and more isolated, and spent his last years under the spell of 'totally unfounded financial worries and a paranoid fear of bankruptcy, persecution and illness.' He was killed in 1966 at the age of 85, struck by a vehicle while crossing the street in front of his house.">>

neufer wrote:

• That's despicable

Joe wrote:Well, I get the gist of what you mean, and I understand that you're also writing for young people as well as the lay person, but I would appreciate it if you call things what they really are, "hot gas" is actually plasma at these temperatures, and can only be plasma. To call it 'hot gas' is doing your readers a disservice, it makes them think it's like here on Earth only hotter, it isn't, it's fundamentally different.

Jaime wrote:
Impressive image of the chromosphere!
But I think they meant fibrils instead of spicules.

• That's despicuble

http://en.wikipedia.org/wiki/Spicule_%28solar_physics%29 wrote:

Click to play embedded YouTube video.

Father Angelo Secchi

<<In solar physics, a spicule is a dynamic jet of about 500 km diameter in the chromosphere of the Sun. It moves upwards at about 20 km/s from the photosphere. They were discovered in 1877 by Father Angelo Secchi of the Vatican Observatory in Rome.

Spicules live for about 5–10 minutes; at the solar limb they appear elongated (if seen on the disk, they are known as "mottles" or "fibrils"). They are usually associated with regions of high magnetic flux; their mass flux is about 100 times that of the solar wind.

At any one time there are around 60,000 to 70,000 active spicules on the Sun; an individual spicule typically reaches 3,000-10,000 km altitude above the photosphere.

Bart De Pontieu (Lockheed Martin Solar and Astrophysics Laboratory, Palo Alto, California ), Robert Erdélyi and Stewart James (both from the University of Sheffield, Sheffield, UK) hypothesised in 2004 that spicules formed as a result of p-mode oscillations in the Sun's surface, sound waves with a period of about five minutes that causes the Sun's surface to rise and fall at several hundred meters per second. Magnetic flux tubes that tilted away from the vertical can focus and guide the rising material up into the solar atmosphere to form a spicule. There is still however some controversy about the issue in the solar physics community.>>

ChuckN wrote:Hmm. Appears that today's APOD and the high resolution image you get when you click it are left-right mirror images of each other.
For a long time my computer monitor background photo has been a retrograde motion one from APOD; I'm tempted to replace it with this one.