The rich black hole? What are the measurements trying to carry out astronomers? Where to find building blocks of life? On this and other issues in the review of the main achievements of astrophysics.
Red same offset
Sometimes astronomers can boast of astronomical accuracy. But in fact, to measure the parameters of physical systems at distances in millions of light years — not an easy task, and high accuracy is not expected. Recent example — check that the red shift of distant galaxies do not depend on the wavelength. If anyone forgot, the red shift is a shift of all lines in the spectra of a galaxy in the direction of a longer wavelength (i.e. in the red part of the spectrum). The wavelength of the lines is increased z times, i.e., Δλ=λ-λ0=z⋅λ0, where λ0 is the wavelength of line for an observer in a distant galaxy, and λ is the wavelength of the same line measured on the Ground.
C a fundamental point of view, the redshift due to the expansion of the Universe. All the galaxies, in General, receding from us, which leads to a Doppler shift of lines. And the value of z is not that other, as simply the ratio of the speed of the galaxy to the speed of light (in first approximation): z = v/c.
The displacement of spectral lines in distant galaxies in the direction of greater lengths
waves due to the expansion of the Universe. All lines should be shifted
on their own wavelengths in the same number of times
This number is obviously universal to the entire galaxy, and, therefore, the shift amount Δλ of lines in different parts of its spectrum must be different from the initial position λ0
Although, in principle, it is possible to try to offer another explanation. So, at the dawn of cosmology was discussed, for example, the hypothesis of “aging photons”, which gradually lose their energy (and blushing) as you travel through space. This hypothesis assumes that the lines in the red part of the spectrum of the galaxy will be displaced otherwise than in the blue, that is, will correspond to a different z. However, there are several other effects like redshift in this case, it should be observed in the spectra of stars in our own Galaxy. But all these effects are not confirmed by observations. So today, the hypothesis about the aging of photons seriously consider.
But this does not negate other ideas, though they are likely to take into account subtle effects in redshift, rather than expect to close the expansion of the Universe. And this makes sense as more accurate verification based on the red shift of the wavelength.
In the latest work of Spanish astronomers analyzed the spectra of 330 thousand galaxies obtained through Kaunasskogo digital sky survey (SDSS). The studied galaxies are located at distances of up to nearly 3 billion light-years (zmax = 0.25). Selecting in the spectrum of around 60 different lines, the scientists showed that their red shifts in different parts of the spectrum, if different, it is not more than z ~ 10-5 (one-thousandth). This limit is limited by the accuracy of the observations, that is, within the available data it is impossible to speak about any differences at this level of accuracy. But this does not mean that larger volume of more accurate data will allow to detect the weak points of deviation.
So the story does not end here, and a similar test in the future will hold many more times. The Foundation for it, in principle, will never disappear, because you can always imagine that there is some unknown physics that lead to such effect, and who would refuse a chance to access this physics.
Get out of here!
The life of galaxies, a gigantic stellar “Islands”, such as our own milky Way — in its simplest presentation is as follows. After a few hundred million years after the Big Bang, the gas filling the Universe, under the influence of dark matter boring in dense clouds (protogalaxies), inside which the same gas was formed tens of billions more “small” and dense protostars. Fast start thermonuclear reactions, and have there been any real stars, and this whole giant system connected with their own gravity, became a galaxy. In some point in its center was a supermassive black hole. It is not clear how exactly, but there.
It turns out that almost all of the gas from which the galaxy was going to become a star. And observational fact is that already a few billion years ago the rate of star formation (rate of emergence of new stars) in most of the small galaxies has slowed down. Because the initial gas reserves has already been spent, and new stars formed just not anything else. Logical? And here and there. Because, first of all, who said that the galaxy and its Central black hole do not particularly fall remains the primary gas from the intergalactic medium? And even entire small galaxy. Under the action of gravity, of course. This process is completely to fuel the star formation, and observations confirm this possibility.
And secondly, the stars in galaxies are rather rough way of life — they expire on the substance, they shed the shell, to explode finally. That is, in the interstellar medium in the galaxy is constantly comes a new building material. And it is estimated that it is more than necessary to explain the observed weak rate of star formation most galaxies. So, there must be some mechanism that sweeps or “excess” gas from the galaxy, or at least prevent it going into the stars.
Galaxy Akira and her companion, for example where the authors show
the phenomenon of galactic “geyser”. In the lower figure: (a) schematic
shows the flow of matter from the galactic center (shown in yellow) with
the structure of the double cone (purple and green). Red arrow
specifies the direction of line of sight. (b) velocity Field of gas in the galaxy
according to the results of observations. Blue color shows gas that is moving on us
red from us. (c) Simulated velocity field in the framework of the idea
galactic geyser.
Candidate for the role of this mechanism in recent years has seen the wind (i.e., outflow of matter) from the Central black hole. Last not absorb all that is around her. The path of matter in the strongly curved space near the black hole is non-trivial, and part of the substance can be ejected. But sure confirmation of the Supervisory BH-winds in these galaxies until recently, was not.
Now a large international team of astronomers, using the data of the same Kaunasskogo digital sky survey (SDSS), found that the number of such galaxies does occur, the gas outflow from the Central region of the galaxy, in the form of two symmetrical cones. This discharge appears to be associated with the Central black hole. A geyser (as it was called by the authors) eventually warms up a bit the gas of the interstellar medium inside the galaxy, preventing it from effectively gather new stars. Because in order to begin to collapse, the gas must have time to efficiently cool down.
What, in General, solves the problem of small rate of star formation in these galaxies.
Someone phosphorus is not enough?
There is a science at the intersection of astrophysics and chemistry — Astronomia. It examines the interaction and mutual transformation of substances, components of the interstellar medium. Such substances, a great variety. Complex molecules are often formed in the atmospheres proevolutionsoccer stars, with enough “cool” to relations between the individual atoms is not destroyed almost immediately. And then, in the form of a stellar wind or shed shell, formed matter into the interstellar medium. As shown by direct spectral observations, these emissions are detected and sodium chloride NaCl (table salt) and TiO2 (oxide, aka food coloring E171) and ethanol C2H5OH.
But especially interesting is, of course, be detected in space organic molecules-the components of living organisms. Although the chemical reactions in which molecules are assembled from individual atoms, are good in earthly terms, some atomic building blocks could fall to the Ground still in the process of formation of our planetary system from the original molecular cloud.
One of these blocks is a molecule of phosphorus monoxide (PO), which is an important component of nucleotides that form the DNA of living organisms, and is also part of ATP (adenosine triphosphate) main energy source for many biochemical processes.
Molecule PO saw in space, relatively recently, about 10 years ago, but discovered she was in the shell of a hypergiant VY Canis major. Such stars live only a few hundred thousand years and die with a big explosion, adding the chemical diversity of the interstellar medium. Ejected material can then serve as building blocks for new, more metallinou (i.e. with a high content of elements heavier than helium) of stars. And the question arises: how is going through all these metamorphoses pair PO? And experiencing it at all? If so, this molecule should be observed not only in the shells of old stars, but also in regions of star formation, where it’s going to be part of a star or a protoplanetary disk. The answer to this question we now have, and it is positive.
A group of astrophysicists from four countries, including Russia, carrying out observations at 30-meter radio telescope of the international Institute IRAM, reported the first detection of spectral lines corresponding to the molecule, PO, in two regions of star formation — W51 and W3(OH). Thus, we have found experimental “missing link”, linking education monoxide in the atmosphere of old stars and its part in the formation of new stars.
Star-forming region W3(OH) – in a white circle. The image is obtained with a space telescope. Herschel
Although it would be wrong to say that one pair PO once formed in the atmosphere of one star and is now safely become part of new stars. As mentioned above, chemical reactions start easier than, say, fusion, and so the molecules can exchange atoms, ions and electrons, even without special conditions like a gigantic temperatures or pressures. Therefore, during the collapse of molecular clouds (which, in fact, happening in the field of star formation) within it molecules actively interact with each other.
The scientists have simulated this process and showed that the molecule, PO is involved in the whole chain of reactions, which also involved, for example, the molecule PN or “relative” water — hydronium ion H3O+. Due to consistent sharing with them different atoms, the number of PO molecules in the initial (cold) phase of the collapse is still reduced by several orders of magnitude. But then, when the collapsing gas is heated, the amount of monoxide phosphorus, on the contrary, increases in several times exceeding the initial value.
Applegate
Would make a good name for a scandal of some large corporations. But in astrophysics it’s just one of the effects that control the lives of close binary stars. More precisely, it is the name of the discoverer of the effect in 1987, the Americans James applegate and Joseph Patterson described the relationship between magnetic cycles of one star (the same 11-year cycles of our Sun) and changes in the orbit of another star, with one component of the system.
Scientists have offered a very beautiful mechanism. Cyclical magnetic activity of the stars, conventionally called stars like the Sun, associated with the restructuring of the magnetic field inside them. But the magnetic field, as we know even from school, it’s matter. It weighs and can exert pressure. Different topology of the field inside the star gives a different contribution to the balance of forces which, on the one hand, seeking to compress the star point (the gravitational force), and on the other, prevent the collapse in the first place — the gas pressure due to the heated by thermonuclear reactions in the subsurface). Thus, the change of the field structure causes variations of pressure in different parts of the star, and hence to a small deformation of its shape, affecting the shape of the gravitational potential. Finally, last step: change the gravity of one star affects the orbit of another star. Well, the planet.
In principle, this mechanism is universal and applicable even to our solar system. But in order to do significantly affect the life of the couple the star (or star-planet), the system itself, first, must be sufficiently compact so as to large distances change gravothermal impact is already weak, and secondly it is necessary that the magnetic field of the “main” star was relatively stronger than our Sun can not boast (not counting patches). Therefore, the effect Applegate rather applicable to smaller in size and cooler red dwarfs, especially forming part of a very close (sometimes even contact) binary systems.
Computing housing SDSS
Why is this even necessary? In order to study magnetic activity of stars, especially when directly (spectral methods) it is good to measure the magnetic field fails.
Due to the applegate mechanism, we can not watch for the star, and the orbit of its companion that much easier. Thus, in systems with eclipses simply measure the period between them and to follow the variations of its magnitude. The effect will manifest itself in about ten years, when the reconstructed magnetic field. In recent years, due to large-scale surveys of the sky type SDSS, mentioned above, we were able to open a lot of close eclipsing systems, which may be affected by the applegate effect. And is stronger in systems where we assume strong magnetic field (and high activity).
Astronomers in a dozen telescopes watched 15-20 years for nearly 70 such systems. The result: a truly, long-term monitoring of the system indicate the variations of the orbital period, explained in terms of the effect Applegate. Moreover, the authors say that this can explain the behaviour of all investigated systems, with rare exceptions. That is just not obvious, because there are other factors that can affect the orbit of the binary system. For example, unrecorded planet. Which, apparently, is not easy to form (and stay) in a close binary system.
