Researchers creates tool that analyzes variable objects

The research used data obtained by the VVV survey and one of its results is the creation of a variable stars’ catalog.

The future implementation of large telescopes has made necessary to define and develop new strategies to study the light coming from astronomical objects, one of them being the statistical analysis of the information obtained. That is why a study led by the Millennium Institute of Astrophysics researcher Nicolás Medina applied an automatic system that searches and characterizes stars whose brightness varies over time using images extracted from the VISTA Variables in the Vía Láctea Survey (VVV). Amelia Bayo, Millenium Nucleus of Planet Formation Director,  is also part of this study.

Using statistical criteria, this research focused on a particular type of variable object, known as YSOs (Young Stellar Objects) but also it quantified the variability of other types of stars and events, such as stars with periodic cycles. “Variable sources give us crucial information about the physical processes that may be occurring. From the characterization of these changing flow patterns we can infer structures, distance scales and also obtain new information from astronomical objects that have been studied several times,” Nicolás Medina explains, who is also a graduate student of the Institute of Physics and Astronomy at Universidad de Valparaíso (IFA).

The VVV survey observes the Milky Way’s central parts through five bands of the near infrared. The total area of this survey is 520 square degrees, which has been divided into zones and each of them observed at different times. These time-spaced observations are known as epochs. To do the research, astronomers analyzed images that they got thanks to the same filter during different epochs in order to analyze the difference in brightness of objects over time. Statistical tools were used for this purpose.

Given that the astronomical timescales are huge, Amelia Bayo, who is also professor at IFA, explains that to see some kind of evolution, data are commonly taken from objects that appear to be different in age in order to construct a time sequence, which is not necessary in the case of variable objects. “They show us changes in their structures or in physical processes that can be monitored on our own timescales and are therefore fascinating. In particular, some objects are extremely stable in their variability and this means that we can measure the distances to them in a very precise way, or that they are actually two objects: one eclipsing the other (one of them may even be a planet.) Others are extremely irregular and these irregularities can be related to episodes of intense mass gain because of the central object -in the case of systems- during the formation process, which impacts on planet formation, to give an example,” the astronomer states.

“This work leaves more questions than certainties, as we have shown that our method finds variable stars that share the same properties in very different regions of the sky. This is why we are now discussing what kind of phenomena it is possible to investigate using the VISTA telescope’s large field -used by the VVV survey to obtain the images-,” Medina utters.

One of the results of this study, according to the researcher, is the creation of a catalog of variable stars in which information about interesting sources for researchers will be added in time.

The methodology developed in this research will be applied systematically in different regions of the galaxy observed by the VVV database. In particular, the researchers will focus on star-forming regions located in the galactic center.

Leave a Reply

Your email address will not be published.