From the southern sky - Phoenix

The southern sky

Phoenix

Phoenix constellation lies in the southern sky. It was named after the phoenix, the mythical bird that rises from its own ashes.

The constellation was originally introduced by the Dutch astronomer and cartographer Petrus Plancius from the observations of the Dutch navigators Frederick Houtman and Pieter Dirkszoon Keyser in the late 16th century. It is a relatively small constellation, but it is the largest among the 12 constellations created and named by Plancius. It was first depicted on his globe in 1598 and later appeared in Johann Bayer’s atlas Uranometria in 1603.

Phoenix constellation is easy to see for anyone in Australia and South Africa during southern hemisphere summer, but generally can’t be observed by anyone living north of the 40th parallel, and lies pretty low in the sky for observers north of the equator.

Phoenix contains several notable deep sky objects, among them the Phoenix Cluster of galaxies, the black hole candidate HLX-1, and Robert’s Quartet, a compact galaxy group.

Phoenix is the 37th constellation in size, occupying an area of 469 square degrees. It is located in the first quadrant of the southern hemisphere (SQ1) and can be seen at latitudes between +32° and -80°. The neighboring constellations are Eridanus, Grus, Fornax, Hydrus, Sculptor and Tucana.

Phoenix belongs to the Johann Bayer family of constellations, along with Apus, Chamaeleon, Dorado, Grus, Hydrus, Indus, Musca, Pavo, Tucana and Volans.

Phoenix contains five stars with known planets and does not have any Messier objects. The brightest star in the constellation is Ankaa (Alpha Phoenicis) with an apparent magnitude of 2.40. There is one meteor shower associated with the constellation -the Phoenicids-which occurs around December 5 every year

French explorer and astronomer Nicolas Louise de Lacatle charted and designated 27 starts with the Bayer designation Alpha through to omega in 1756, of these he labelled two stars close together lambda and assigned omicron, psi and omega to three stars.

MAJOR STARS IN PHOENIX

1. Ankaa – α Phoenicis (Alpha Phoenicis)

2. β Phoenicis (Beta Phoenicis)

3. γ Phoenicis (Gamma Phoenicis)

4. κ Phoenicis (Kappa Phoenicis)

5. ζ Phoenicis (Zeta Phoenicis)

6. ν Phoenicis (Nu Phoenicis)

7. SX Phoenicis

Brightest star - Ankaa or Alpha Phoenicis

Ankaa is the brightest star in the constellation. Its name comes from the Arabic al- ‘anqā’, which means “the phoenix.” It is also sometimes known as Nair al- Zaurak, or “the bright star of the skiff” (an-na’ir az-zawraq in Arabic).

Alpha Phoenicis is a spectroscopic binary star approximately 85 light years distant. The system has the combined stellar classification K0.5 IIIband a combined apparent magnitude of 2.377. The two components in the system orbit each other with a period of 3848.8 days (or 10.5 years). The primary star, as the spectral class indicates, is an orange giant.

Water on Mars

Water on Mars

Introduction

Mars is the fourth planet from the Sun and the second smallest planet in the Solar system after Mercury. Have you heard the big news!?

NASA has reported there is water on Mars. Let’s travel to the Mars now..

Using an imaging spectrometer on NASA’s Mars Reconnaissance Orbiter(MRO), researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet.

These dark, narrow 100 meter-long streaks called ‘recurring slope lineae’(RSL) flowing downhill are inferred to have been formed by contemporary flowing water. Recently, planetary scientists detected hydrated salts on these slopes at Hale crater, corroborating their original hypothesis that the streaks are indeed formed by liquid water.

Another view of ‘recurring slope lineae’ or RLSs, flowing out of a mountainside on Mars.

Almost all water on Mars today exists in small quantities as vapour in the atmosphere and occasionally as low volume liquid brines in shallow Martian soil. The only plane where water ice is visible at the surface is at the north polar ice cap.

Scientists have also travelled deep underground into mines and found microorganisms related to ancient species that once lived in watery environments much close to the surface. Such migrations raise the possibility of the same thing happening on Mars- as the water retreated, life moved deeper underground.

However, while the find is tantalizing for astrobiologists eager to find alien life, it is also a bit of tease. It will be decades before astronauts can visit the surface of Mars and likely much longer before we can drill a mile beneath the dusty surface. So we may not see any expeditions in our lifetime.

Observations of the Red planet indicate that rivers and oceans may have been prominent features in its early history. Billions of years ago, Mars was warm and wet world that could have supported microbial life in small regions. But the planet is smaller than Earth, with thinner atmosphere. Over the time, as liquid water evaporated, more and more of it escaped into space, allowing less to fall back to the surface of the planet.

More than five million cubic kilometres of ice has been identified at or near to cover the whole planet to a depth of 35 meters.

Although there are some extremophile organisms that survive in hostile condition on Earth, including stimulations that approximate Mars, plants and animals generally cannot survive the ambient conditions present on the surface of Mars. Surface gravity of Mars is 38% of Earth. Researches are going on this area.

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1^st M.Sc. Physics

Reference

• Internet
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SPECTRUM

Spectrum

Introduction

A spectrum is a condition that is not limited to a specific set of values but can vary, without steps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colours in visible light after passing through a prism.  As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum.

In the 17th century, the word spectrum was introduced into optics by Isaac Newton, referring to the range of colours observed when white light was dispersed through a prism. Soon the term referred to a plot of light intensity or power as a function of frequency or wavelength, also known as a spectral density plot.

The term spectrum was expanded to apply to other waves, such as sound waves that could also be measured as a function of frequency, frequency spectrum and power spectrum of a signal.

Electromagnetic spectrum

Electromagnetic spectrum refers to the full range of all frequencies of electromagnetic radiation and also to the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object. Devices used to measure an electromagnetic spectrum are called ‘spectrograph’ or ‘spectrometer’. The visible spectrum is the part of the electromagnetic spectrum that can be seen by the human eye. The wavelength of visible light ranges from 390 to 700nm. The absorption spectrum of a chemical element or chemical compound is the spectrum of frequencies or wavelengths of incident radiation that are absorbed by the compound due to electron transitions from a lower to a higher energy state.

Light from many different sources contains various colours, each with its own brightness or intensity. A rainbow, or prism, sends these component colours in different directions, making them individually visible at different angles. A graph of the intensity plotted against the frequency is the frequency spectrum of the light. When all the visible frequencies are present equally, the perceived colour of the light is white, and the spectrum is a flat line.

In radio and telecommunications, the frequency spectrum can be shared among many different broadcasters. The radio spectrum is the part of the electromagnetic spectrum corresponding to frequencies lower below 300 GHz, which corresponds to wavelengths longer than about 1 mm. The microwave spectrum corresponds to frequencies between 300 MHz (0.3 GHz) and 300 GHz and wavelengths between one meter and one millimeter.

Mass spectrum

A plot of ion abundance as a function of mass to charge ratio is called a mass spectrum. It can be produced by a mass spectrometer instrument. The mass spectrum can be used to determine the quantity and mass of atoms and molecules.

Energy spectrum

In physics, the energy spectrum of a particle is the number of particles or intensity of a particle beam as a function of particle energy. Examples of techniques that produce an energy spectrum are alpha particle spectroscopy, electron energy loss spectroscopy, and mass analyzed ion kinetic energy spectrometry.

Discrete spectrum

In physics, particularly in quantum mechanics, some differential operator have discrete spectra, with gaps between values. Common cases include the Hamiltonian and the angular momentum operator.

Spectrogram

In acoustics, a spectrogram is a visual representation of the frequency spectrum of sound as a function of time or another variable.   An apparatus used for recording and measuring spectra, especially as a method of analysis.

Splitting of white light

Light changes speed as it moves from one medium to another (for example, from air into the glass of the prism). This speed change causes the light to be refracted and to enter the new medium at a different angle. The degree of bending of the light's path depends on the angle that the incident beam of light makes with the surface, and on the ratio between the refractive indices of the two media. 

Light of different colours to  be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow. This can be used to separate a beam of white light into its constituent spectrum of colours.

Reference

·        Wikipedia

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Ahallya K V

Akshatha G

Akhila K

Athira V

Amal George