Astronomers first managed to identify the pattern in the high frequency pulsations of variable stars like Delta Shield. The obtained result will help to define and clarify a number of properties of objects of this class. Work published in the journal Nature.
Variables are called stars, who at least once have managed to register the change of brightness. The reasons for such changes may be physical phenomena of different nature: for example, the recent tarnishing of the supergiant Betelgeuse, scientists first connected with the approaching death star, and then explained the movement of dust clouds.
Among the variable stars researchers have identified a class of pulsating — changing their Shine is recurrent and caused by processes that occur in the depths of the star. In turn, pulsating stars are divided into types, one of which astronomers have named after the Delta of the constellation of the Shield is a heavenly body can be seen with the naked eye in the southern hemisphere of the sky. Changes in the brightness of variables, the Delta of the Shield occurs due to the complex oscillations of their surface. These stars are radial (i.e., spherically symmetric), and predelnye the ripple with a cycle time of a few hours that overlap each other and become complex. As a result of change of Shine of the stars seem to be messy — their amplitude and period are constantly changing, and to see a clear pattern in this process, spreading the vibrations on a separate fashion — that is, the basic components for a long time no one could.
The research team from nine countries, headed by Australian Timothy Bedding (Timothy R. Bedding) from Sydney Institute of astronomy, went in search of the regular component in the ripple of brightness variables of the Delta Shield. For this, the authors have used in the first place, the data space telescope TESS (Transiting Exoplanet Survey Satellite), which he filmed between 25 July 2018 25 March 2019. The main purpose of this unit is to search for exoplanets, but in the fall of his many pulsating stars. Images the telescope produces every two minutes — this allows us to observe the high frequency oscillations characteristic of type variables of the Delta Shield, sufficient for the analysis of temporal resolution. Supportive role in research was played by observations from spacecraft Kepler (for the entire period his primary mission from March 2009 to may 2013), the principle of operation is similar to that of TESS. To obtain a spectrum at high resolution, scientists have used measurements of ground-based telescopes the Keck Observatory on the island of Hawaii (April-may 2019) and a network of observatories Las Cumbres (Las Cumbres) in Chile and South Africa (may to June 2019). In total, the astronomers analyzed about 92 thousands of the light curves (i.e., dependences of brightness of the stars from time to time), at a cost of several days of computer processing.
As a result, scientists have found the first regular fluctuations in 60 of variable stars — in the future this will allow to further study the mechanisms of pulsations that affect apparent gloss. The analysis of fluctuations is also an opportunity to establish other important properties of celestial bodies that are associated with this process — for example, to distinguish the young from the old lights. Thus, the study helped in determining the age of a newly opened star HD 31901, different scores which gave values between 120 million to a billion years. Data obtained by the authors, testify in favor of the first assumption.
Astronomers are going to continue processing with TESS, when the device will go into a new mode of operation will be every ten minutes to make a full-sized pictures of the sky according to NASA plans, this should happen in July of this year.
Earlier we talked about how with the help of TESS found a rare magnetic star and saw the explosion on the comet Virtanen.