Scientists explain why oxygen does not “escape” from the Galaxy

(ORDO NEWS) — An international team of scientists with the participation of employees of Peter the Great St. Petersburg Polytechnic University (SPbPU) discovered an error in the calculations of the velocity of interstellar atomic oxygen, which explains the fact why it does not leave the Galaxy. The results of the study were published in the journal Physical Review Letters, the press service of the 5-100 project for increasing the competitiveness of Russian universities told TASS on Tuesday.

“We have corrected the values ​​of all X-ray lines in atomic oxygen in the fourth significant digit. Some may think that the fourth digit is a trifle and uninteresting, but we see that even such a small error can lead to serious astrophysical problems. It is from such results that scientific progress. Step by step we are getting rid of mistakes, “said Vladimir Erokhin, Chief Researcher of the Department of the Center for Advanced Studies of SPbPU, whose words are quoted in the message.

Earlier, the American orbiting X-ray telescope Chandra measured the absorption spectra of interstellar gas in our Galaxy with record accuracy. By comparing the spectra of various chemical elements from galactic objects with similar spectra obtained in laboratory conditions, astrophysicists determine the speed of movement of objects relative to the Earth.

The results of the analysis of the Chandra spectra showed that interstellar atomic oxygen moves at a speed of about 340 km / s, which is much higher than the speed of movement of other interstellar gases (about 100 km / s) and is enough for some of the interstellar oxygen to leave the Galaxy over time. … Moreover, the data from Chandra was then confirmed by the XMM-Newton telescope. The most plausible explanation for this discrepancy was considered an error in the calibration of orbital spectra, that is, laboratory data.

The international collaboration of German research centers and the US National Aerospace Agency (NASA) with the participation of SPbPU scientists decided to confirm or deny this version. In the new work, they carried out high-precision measurements of the X-ray absorption lines of atomic oxygen using an electron beam ion trap (EBIT) and a BESSY II synchrotron radiation source in Berlin.

To calibrate the spectra, the researchers used a method that used the lines of multiply charged oxygen and nitrogen ions. This method is superior in accuracy to other methods previously used for this purpose. As a result, it was found that the existing literature data for laboratory X-ray absorption lines of oxygen were shifted by 0.45 eV (approximately by one in the fourth digit). After the laboratory data were corrected, the speed of interstellar oxygen decreased by 250 km / sec and the “oxygen mystery” in the spectra of X-ray telescopes was solved.


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