Tag Archives: blue

This spectacular image of the star cluster Messier 47 was taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. This young open cluster is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars.

Credit:
ESO

The Hot Blue Stars of Messier 47

This spectacular image of the star cluster Messier 47 was taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. This young open cluster is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars.

Messier 47 is located approximately 1600 light-years from Earth, in the constellation of Puppis (the poop deck of the mythological ship Argo). It was first noticed some time before 1654 by Italian astronomer Giovanni Battista Hodierna and was later independently discovered by Charles Messier himself, who apparently had no knowledge of Hodierna’s earlier observation.

Although it is bright and easy to see, Messier 47 is one of the least densely populated open clusters. Only around 50 stars are visible in a region about 12 light-years across, compared to other similar objects which can contain thousands of stars.

Messier 47 has not always been so easy to identify. In fact, for years it was considered missing, as Messier had recorded the coordinates incorrectly. The cluster was later rediscovered and given another catalogue designation — NGC 2422. The nature of Messier’s mistake, and the firm conclusion that Messier 47 and NGC 2422 are indeed the same object, was only established in 1959 by Canadian astronomer T. F. Morris.

This spectacular image of the star cluster Messier 47 was taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. This young open cluster is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars. Credit: ESO
This spectacular image of the star cluster Messier 47 was taken using the Wide Field Imager camera, installed on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. This young open cluster is dominated by a sprinkling of brilliant blue stars but also contains a few contrasting red giant stars.
Credit:
ESO



The bright blue–white colours of these stars are an indication of their temperature, with hotter stars appearing bluer and cooler stars appearing redder. This relationship between colour, brightness and temperature can be visualised by use of the Planck curve. But the more detailed study of the colours of stars using spectroscopy also tells astronomers a lot more — including how fast the stars are spinning and their chemical compositions. There are also a few bright red stars in the picture — these are red giant stars that are further through their short life cycles than the less massive and longer-lived blue stars [1].

By chance Messier 47 appears close in the sky to another contrasting star cluster — Messier 46. Messier 47 is relatively close, at around 1600 light-years, but Messier 46 is located around 5500 light-years away and contains a lot more stars, with at least 500 stars present. Despite containing more stars, it appears significantly fainter due to its greater distance.

Messier 46 could be considered to be the older sister of Messier 47, with the former being approximately 300 million years old compared to the latter’s 78 million years. Consequently, many of the most massive and brilliant of the stars in Messier 46 have already run through their short lives and are no longer visible, so most stars within this older cluster appear redder and cooler.

This image of Messier 47 was produced as part of the ESO Cosmic Gems programme [2].

Notes

[1] The lifetime of a star depends primarily on its mass. Massive stars, containing many times as much material as the Sun, have short lives measured in millions of years. On the other hand much less massive stars can continue to shine for many billions of years. In a cluster, the stars all have about the same age and same initial chemical composition. So the brilliant massive stars evolve quickest, become red giants sooner, and end their lives first, leaving the less massive and cooler ones to long outlive them.

[2] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

More information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning the 39-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Source: ESO 

Physicists from Japan and USA shared 2014 Physics Nobel Prize

The Nobel Prize in Physics 2014 was awarded jointly to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura “for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources”.

Following is the press release from NobelPrize.Org regarding the announcement.


The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2014 to

Isamu Akasaki
Meijo University, Nagoya, Japan and Nagoya University, Japan

Hiroshi Amano
Nagoya University, Japan

and

Shuji Nakamura
University of California, Santa Barbara, CA, USA

“for the invention of efficient blue light-emitting diodes which has enabled bright and energy-saving white light sources”

New light to illuminate the world

This year’s Nobel Laureates are rewarded for having invented a new energy-efficient and environment-friendly light source – the blue light-emitting diode (LED). In the spirit of Alfred Nobel the Prize rewards an invention of greatest benefit to mankind; using blue LEDs, white light can be created in a new way. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources.

When Isamu AkasakiHiroshi Amano and Shuji Nakamura produced bright blue light beams from their semi-conductors in the early 1990s, they triggered a funda-mental transformation of lighting technology. Red and green diodes had been around for a long time but without blue light, white lamps could not be created. Despite considerable efforts, both in the scientific community and in industry, the blue LED had remained a challenge for three decades.

They succeeded where everyone else had failed. Akasaki worked together with Amano at the University of Nagoya, while Nakamura was employed at Nichia Chemicals, a small company in Tokushima. Their inventions were revolutionary. Incandescent light bulbs lit the 20th century; the 21st century will be lit by LED lamps.

White LED lamps emit a bright white light, are long-lasting and energy-efficient. They are constantly improved, getting more efficient with higher luminous flux (measured in lumen) per unit electrical input power (measured in watt). The most recent record is just over 300 lm/W, which can be compared to 16 for regular light bulbs and close to 70 for fluorescent lamps. As about one fourth of world electricity consumption is used for lighting purposes, the LEDs contribute to saving the Earth’s resources. Materials consumption is also diminished as LEDs last up to 100,000 hours, compared to 1,000 for incandescent bulbs and 10,000 hours for fluorescent lights.

The LED lamp holds great promise for increasing the quality of life for over 1.5 billion people around the world who lack access to electricity grids: due to low power requirements it can be powered by cheap local solar power.

The invention of the blue LED is just twenty years old, but it has already contributed to create white light in an entirely new manner to the benefit of us all.

Read more about this year’s prize
Information for the Public
Pdf 1.1 MB
Scientific Background
Pdf 770 kB
To read the text you need Acrobat Reader.

Image – diode (1.1 Mb)

Image – efficiency (2.8 Mb)

Image – white sign (12.4 Mb)


 

Isamu Akasaki,, Japanese citizen. Born 1929 in Chiran, Japan. Ph.D. 1964 from Nagoya University, Japan. Professor at Meijo University, Nagoya, and Distinguished Professor at Nagoya University, Japan.
http://en.nagoya-u.ac.jp/people/distinguished_award_recipients/nagoya_university_distinguished_professor_isamu_akasaki.html

Hiroshi Amano,, Japanese citizen. Born 1960 in Hamamatsu, Japan. Ph.D. 1989 from Nagoya University, Japan. Professor at Nagoya University, Japan.
http://profs.provost.nagoya-u.ac.jp/view/html/100001778_en.html

Shuji Nakamura, American citizen. Born 1954 in Ikata, Japan. Ph.D. 1994 from University of Tokushima, Japan. Professor at University of California, Santa Barbara, CA, USA.
www.sslec.ucsb.edu/nakamura/

Prize amount: SEK 8 million, to be shared equally between the Laureates.

Source: NobelPrize.Org