Astronomy Picture of the Day for November 20th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 November 20
See Explanation.  Clicking on the picture will download the highest resolution version available.

W5: Pillars of Star Formation
Image Credit & Copyright: Lori Allen, Xavier Koenig (Harvard-Smithsonian CfA) et al., JPL-Caltech, NASA  

 

Explanation: How do stars form? A study of star forming region W5 by the sun-orbiting Spitzer Space Telescope provides clear clues by recording that massive stars near the center of empty cavities are older than stars near the edges. A likely reason for this is that the older stars in the center are actually triggering the formation of the younger edge stars. The triggered star formation occurs when hot outflowing gas compresses cooler gas into knots dense enough to gravitationally contract into stars. Spectacular pillars, left slowly evaporating from the hot outflowing gas, provide further visual clues. In the above scientifically-colored infrared image, red indicates heated dust, while white and green indicate particularly dense gas clouds. W5 is also known as IC 1848, and together with IC 1805 form a complex region of star formation popularly dubbed the Heart and Soul Nebulas. The above image highlights a part of W5 spanning about 2,000 light years that is rich in star forming pillars. W5 lies about 6,500 light years away toward the constellation of Cassiopeia.

Astronomy Picture of the Day for November 8th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 November 8

Jumping Sundogs Over Thunderclouds
Image Credit: abrigatti, YouTube 

 

Explanation: What’s happening above those clouds? In the past few years, videos have appeared on the web detailing an unusual but little known phenomenon: rapid light changes over clouds. Upon inspection and contemplation, a leading hypothesis for its cause has now emerged. In sum, this hypothesis holds that a lightning discharge in a thundercloud can temporarily change the electric field above the cloud where charged ice crystals were reflecting sunlight. The new electric field quickly re-orients the geometric crystals to a new orientation that reflects sunlight differently. In other words, a lightning discharge can cause a sundog to jump. Soon, the old electric field may be restored, causing the ice crystals to return to their original orientation. To help this curious phenomenon become better studied, sky enthusiasts with similar jumping or dancing sundog videos are encouraged to share them.

Astronomy Picture of the Day for November 7th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 November 7
See Explanation.  Clicking on the picture will download the highest resolution version available.

Star Forming Region S106
Image Credit: GRANTECAN and IAC 

 

Explanation: Massive star IRS 4 is beginning to spread its wings. Born only about 100,000 years ago, material streaming out from this newborn star has formed the nebula dubbed Sharpless 2-106 Nebula (S106), pictured above. A large disk of dust and gas orbiting Infrared Source 4 (IRS 4), visible in dark red near the image center, gives the nebula an hourglass or butterfly shape. S106 gas near IRS 4 acts as an emission nebula as it emits light after being ionized, while dust far from IRS 4 reflects light from the central star and so acts as a reflection nebula. Detailed inspection of images like the above image has revealed hundreds of low-mass brown dwarf stars lurking in the nebula’s gas. S106 spans about 2 light-years and lies about 2000 light-years away toward the constellation of the Swan (Cygnus).

Astronomy Picture of the Day for October 27th

Astronomy Picture of the Day

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2011 October 27
See Explanation.  Clicking on the picture will download the highest resolution version available.

Young Suns of NGC 7129
Image Credit & Copyright: Johannes Schedler (Panther Observatory)Explanation: Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the sharp image are the lovely bluish dust clouds that reflect the youthful starlight. But the compact, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Paler, extended filaments of redish emission mingling with the bluish clouds are caused by dust grains effectively converting the invisible ultraviolet starlight to visible red light through photoluminesence. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic view spans about 40 light-years.

Saucer Meditation (Blood/Harvest Moon)

Saucer Meditation

(Blood/Harvest Moon)

Before you go to sleep, turn on some soft meditative music. Lie back and begin breathing rhythmically by inhaling and counting to three and exhaling and counting to three. Each time you take a deep breath, imagine your lungs filling with the energizing white light of the stars and moon. As you exhale, sense all of the stress and tension in your body being cast out with your breath. A wave of tranquil bliss envelopes you being, sending it into a state of relaxed awareness. At the same time that you are becoming more relaxed, you are becoming more aware of your senses. Your mind is aware of all things at all times.

In your mind’s eye, imagine traveling on a saucer-shaped ship. Before you there is a giant portal and through it you view the many approaching stars. Sirius, Orion’s Belt, and the stars of Big Dipper fly across the portal as you watch with relaxed awareness. A large bluish-green planet comes into view. Its image grows lager on the screen as your flying saucer gets closer, and closer, and closer to it.

You watch as an alien world fills the screen with images that seem foreign but familiar. Alien beings with aqua-colored skin and right golden hair float lightly on emerald-green waves. They smile at you with smiles that send a warm glow through your entire being. You sense a Oneness with them that moves beyond physical barriers and mental limitations. They are your alien friends who you can visit anytime you want in meditation and dream. As you drift to sleep, imagine exploring the universe and all the magickal beings within it.

NASA Image of the Day for October 14th

Carina Nebula: 14,000+ Stars

The Carina Nebula is a star-forming region in the Sagittarius-Carina arm of the Milky Way that is 7,500 light years from Earth and the Chandra X-Ray Observatory has detected more than 14,000 stars in the region.

Chandra’s X-ray vision provides strong evidence that massive stars have self-destructed in this nearby star-forming region. Firstly, there is an observed deficit of bright X-ray sources in the area known as Trumpler 15, suggesting that some of the massive stars in this cluster were already destroyed in supernova explosions. Trumpler 15 is located in the northern part of the image and is one of ten star clusters in the Carina complex.

The detection of six possible neutron stars, the dense cores often left behind after stars explode in supernovas, provides additional evidence that supernova activity is increasing up in Carina. Previous observations had only detected one neutron star in Carina.

Image Credit: NASA/CXC/Penn State/L. Townsley et al.

NASA Image of the Day for Oct. 15th – Trigger-Happy Star Formation

Trigger-Happy Star Formation

This composite image, created using data from the Chandra X-ray Observatory and the Spitzer Space Telescope, shows the molecular cloud Cepheus B, located in our galaxy about 2,400 light years from the Earth. A molecular cloud is a region containing cool interstellar gas and dust left over from the formation of the galaxy and mostly contains molecular hydrogen. The Spitzer data, in red, green and blue shows the molecular cloud (in the bottom part of the image) plus young stars in and around Cepheus B, and the Chandra data in violet shows the young stars in the field.

The Chandra observations allowed the astronomers to pick out young stars within and near Cepheus B, identified by their strong X-ray emission. The Spitzer data showed whether the young stars have a so-called “protoplanetary” disk around them. Such disks only exist in very young systems where planets are still forming, so their presence is an indication of the age of a star system.

These data provide an excellent opportunity to test a model for how stars form. The new study suggests that star formation in Cepheus B is mainly triggered by radiation from one bright, massive star (HD 217086) outside the molecular cloud. According to the particular model of triggered star formation that was tested — called the radiation- driven implosion (RDI) model — radiation from this massive star drives a compression wave into the cloud triggering star formation in the interior, while evaporating the cloud’s outer layers.

Different types of triggered star formation have been observed in other environments. For example, the formation of our solar system was thought to have been triggered by a supernova explosion, In the star-forming region W5, a “collect-and-collapse” mechanism is thought to apply, where shock fronts generated by massive stars sweep up material as they progress outwards. Eventually the accumulated gas becomes dense enough to collapse and form hundreds of stars. The RDI mechanism is also thought to be responsible for the formation of dozens of stars in W5. The main cause of star formation that does not involve triggering is where a cloud of gas cools, gravity gets the upper hand, and the cloud falls in on itself.

Image Credit: X-ray: NASA/CXC/PSU/K. Getman et al.; IRL NASA/JPL-Caltech/CfA/J. Wang et al.