Gamma Ray Bursts GRB

Gamma-ray bursts are bursts of short duration of intense gamma rays lasting from few milliseconds to several minutes. They are the most luminous source in the universe and during the burst, their luminosity even exceed that of a supernova explosion. Usually, there is one GRB day and they are detected from all directions of the sky. It is interesting to describe the history of their detection. In the late 1960s, US military satellites watched for Soviet nuclear testing (nuclear test ban treaty)....

Collisions in the Solar System 531 Case Study Meteor Crater Arizona

On Earth, a meteor impact occurred 50,000 years ago, a crater 180 m deep with a rim rising 30-60 m above the surrounding plain and a diameter of 1,200 m was formed. This crater is known as the Meteor crater or as Barringer Crater (see Fig. 5.6). Kring 130 calculated magnitudes of pressures and wind velocities as a function of distance for that event. He assumed two cases for the energy that was set free 20 megaton and 40 megaton. For comparison, the Hiroshima bomb had only 15 kt equivalent...

Palermo Technical Impact Hazard Scale

The Palermo Technical Impact Hazard scale (see Chesley et al. 38 combines two types of data - probability of impact and estimated kinetic yield - into a single hazard value. The Palermo Scale value P is defined as the ratio of the impact probability Pl to the background impact probability over time in years T to the event A rating of 0 means the hazard is as likely as the background hazard (defined as the average risk posed by objects of the same size or larger over the years until the date of...

Stability of Atmosphere and Magnetosphere

As we have seen, the Earth's atmosphere and the magnetosphere provide an effective shielding against radiation and charged particles. The question is how stable these systems are and have been over the past and what would be the consequences for habitability on Earth if this protection gets considerably weaker. The topic was also recognized by Hollywood producers and a movie appeared in which the collapse of the Earth's magnetic field leads to massive electrical storms, blasts of solar...

The Local Bubble

The local environment of the solar system is different from the conditions found in interstellar matter. The solar system is located in the so-called Local Bubble, which is a cavity in the interstellar medium. The Local Bubble was discovered by measurements of starlight reddening 61 . The Local Bubble void was created by star formation processes. A blast wave evacuated a low density region and compressed surrounding molecular clouds massive OB stars were formed, which is known as Gould's Belt....

The T Tauri Phase of the Early

Generally, T Tauri stars have deep convection zones and rotate very rapidly. Since the stellar dynamo is caused by the interaction of rotation and convection, their energetic flaring activity can be explained. T Tauri stars are surrounded by an accretion disk. The T Tauri stage lasts only for about 3-4 x 106 yr. During the T Tauri phase, jets occur at the polar regions. These jets eject about 2 of the infalling matter from the accretion disk and brake down the high rotation rates of the...

Boron Based Life

Like carbon and silicon, boron has a strong tendency to form covalent molecular compounds. Boron forms a lot of different structural varieties of hydride in Table 8.1 Cosmic abundance of elements. ppm denotes parts per million in mass 739,000 240,000 10,700 4,600 1,340 1,090 these the boron atoms are linked indirectly through hydrogen bridges. Boron forms bonds with nitrogen that are somewhat like the carbon-carbon bond-two electrons from the nitrogen being donated in addition to the covalent...

What does Stability Mean

Two hundred years ago, the solar system was considered a stable system in which no changes occur. Newton formulated the law of gravitation and the laws of motion. From that time, the question arose do we live in a deterministic universe in which all future motions, accelerations, actions, and interactions are determined by the present position and motion of all the particles Such a point of view would imply to negate the notion of free will for humans. Examples of deterministic systems are...

Asteroids

4.2.4.1 Discovery and General Properties Asteroids, also called minor planets or planetoids, are objects smaller than planets and dwarf planets that orbit the Sun, most of them in the asteroid belt between Mars and Jupiter. In the General IAU Assembly in 2006, these objects together with the comets discussed above, are also designated as Small Solar System Bodies (SSSBs). At that assembly, also, a new class of objects was defined the dwarf planets to which Pluto belongs. The first asteroid was...

Main Sequence Lifetime

To study the habitability in a planetary system around main sequence stars, we must take into account the evolution of the host star. About 1 billion years after the formation of the Earth, the first life forms occurred. Maybe there was life even before, but this is uncertain. So, the host star must be stable for at least over 109 years for life to evolve. The evolution and lifetime of a star depends primarily on its mass. The larger the mass, the larger its luminosity, the more the energy...

Definition of the Solar Neighborhood

Solar Neighborhood

The real number of objects near the solar neighborhood (Fig. 7.2) is difficult to determine because there may be many small, not very luminous objects such as brown dwarfs. Kirkpatrick 124 estimates that cool objects like brown dwarfs may outnumber the stars two to one. But because of their small sizes, they contribute only to about 10 of the mass in the solar neighborhood. The sample was restricted to objects within a distance of 25 pc (Fig. 7.3). Fig. 7.2 The Local Bubble and the position of...

Heavy Bombardment Phase

The next phase lasted longer and is also known as heavy bombardment phase from 4.56 x 109 to 3.9 x 109 bp. The area of heavy bombardment in the solar system is documented by the cratered surfaces of all terrestrial planets and many satellites. The crater sizes follow a power law every time the diameter is halved, there are eight times more craters. Between 4.1 and 3.8 billion years, a sharp decrease of the heavy bombardment was found (from the manned Apollo missions). This picture was refined...

Tidal Locking

A well-known example of tidal locking is the Earth-Moon system. From Earth, you can always see the same hemisphere of the Moon. We say that the Moon is tidally locked it takes just as long to rotate around its own axis as it does to complete one revolution around the Earth. Also the term synchronous rotation is used. The Moon is 1 1 tidally locked. Let us consider a smaller body B, which gets locked to a larger body A. The gravity of A produces a tidal force on B. This results in a deviation...

Overview and Formation of the Solar System 4121 Objects in the Solar System

The main body of the solar system is the Sun. The Sun contains 99.8 of the system's known mass. There are two big planets, Jupiter and Saturn, that contain more than 90 of the remaining mass. The eight great planets revolve around the Sun in the same sense and almost in the same plane the plane of the Earth's orbit which is called the ecliptic. Thus, all planetary orbits lie near the ecliptic, which was already known by ancient cultures. Other members of the solar system are the dwarf planets...

Controversy about the KT Impact Theory

There is still some controversy whether the K-T extinction event was really caused by an impact or whether this impact was the main cause for the mass extinction. The Deccan Traps flood basalts (massive volcanic eruptions in India they covered an area roughly the size of France) could have also caused mass extinction. It seems now established 106 that 2 3 of the Deccan Traps occurred over a time span of 1 million years about 65.5 Ma (million years ago) causing a rapid extinction over some 103...

Collisions and Habitability 561 Impacts of Comets

Comets are mainly made of ice, whereas asteroids are made of rock and no ice (some of metals). There is a large uncertainty in the prediction whether a comet would collide with a planet, say, the Earth or not because For newly discovered comets, it is difficult to determine precisely their orbital elements because there are strong residuals from the position of the background stars. As the comet approaches the Sun, its surface warms up and gases (like geysers) burst out of the surface. This...

Comets

The Greek word kome denotes hair of the head and the designation kometes means stars with hair. Often through history people believed that the appearance of comets means something dangerous like war or plagues. After Newton established his law of gravity in 1705, Halley detected that the comets of the years 1531, 1607, and 1682 have very similar orbits and belong to the same object. This comet was named after Halley. It was a big triumph of celestial mechanics when the predicted reappearance of...

Venus

The conditions on the surface of Venus do not seem favorable to be habitable because of the dense atmosphere, the surface temperature ranges from 710 to 770 K. 96.5 of its atmosphere is composed of CO2 (therefore, a strong greenhouse effect) and 3.5 is composed of N2. The water content is 20 ppm. The mean surface pressure is 90 bar. The cloud cover starts at a height of approximately 50 km and there are droplets of sulfuric acid. Big droplets rain down from a height of approximately 50 km and,...

Catastrophes and Habitability in Galaxies 741 Galactic Collisions Starburst Galaxies

Galaxies are found in galaxy clusters. Our galaxy belong to a group of galaxies which is called the Local Group. The average distance between galaxies in a galaxy cluster is only about ten times their diameter. Let us consider our galaxy and its neighboring galaxy, the Andromeda galaxy. The diameter of our galaxy is about 105 Lyr the distance of the Andromeda galaxy is about 20 times this value. Similar proportions between galaxy diameters and their mutual distances are found for other galaxies...

Respiration

Basically, respiration is the release of energy from glucose molecules that are broken down to individual carbon dioxide molecules. This process takes place in all active cells, regardless of whether or not photosynthesis occurs simultaneously in the cells. Respiration is initiated in the cytoplasm and completed in the mitochondria. No oxygen is needed to initiate the process, but in aerobic respiration, the process cannot be completed without O2. The simplified reaction is as follows This...

Stars and Radiation 921 Electromagnetic Radiation

The spectrum of electromagnetic radiation ranges from gamma rays , X-rays, UV, visible light to IR, microwaves, and radiowaves. This is also a sequence of 8 Most cholesterol is synthesized in the body, some is of dietary origin. LDL (low density lipoprotein) is harmful HDL (high density lipoprotein) is thought to be beneficial. decreasing energy and increasing wavelength (decreasing frequency) of the radiation. The wavelength X and frequency v are related by where c 300,000 km s, the speed of...

Tidal Heating 1151 Io

It was a big surprise when on Io (Fig. 1.4), one of the Galilean satellites4 of Jupiter, active volcanism was detected.5 On Earth, the heat source that produces volcanic activity comes from its interior where radioactive materials decay and release energy and also from heat left over from its formation, accretional heat. This, however, cannot explain the volcanism on Io because the satellite is too small. The only explanation is by tidal heating. The semi-major axis of the orbit of Io is...

Active Galactic Nuclei and Habitability

The nucleus of a galaxy is the central region where the concentration of stars is high and mostly spherical. The nucleus of our galaxy cannot be seen in visible light because of dust clouds. We define the nucleus of a galaxy as active when it emits more energy than is expected from the radiation of stars. The explanation for the activity in the nucleus is as follows A SMBH (Supermassive Black Hole) in the center An accretion disk around this object From the accretion disk, matter falls toward...