An international group of astronomers found a star whose brightness increases and decreases without an specified pattern. VVV-WIT-07, as the object was named, belongs to the Milky Way and only two other stars with a similar type of variability are known, in which case the physical mechanism that produces an abrupt decrease in its brightness is also unknown. Claudio Cáceres, assistant researcher at the Núcleo Milenio de Formación Planetaria , participated in this study along with postdoctoral researcher Juan Carlos Beamín, a member of the centre’s outreach team.
The discovery is part of the Vista Variables in the Vía Láctea (VVV) project and its extension, the VVVX, which seeks to determine the three-dimensional structure of our galaxy through the analysis of some special types of variable stars, used as distance indicators. The observations were carried out with the VISTA telescope of the European Southern Observatory, located in the north of Chile. This telescope observes infrared light, which allows it to pass through the dense clouds of gas and dust present in the galaxy and which, from our position as observers on Earth, block its light.
To date, we know only two stars are known whose brightness variations are more or less similar to VVV-WIT-07 (whose name includes the acronym WIT for “what is this”), J1407 and KIC 8462852, a star known as “Tabby Star”.
“In the context of this study, the object was discovered, whose variability cannot be explained by a pulsation phenomenon or any other known cause external to the star. Given the large number of stars that have been monitored in our galaxy, it is interesting that only three present this type of variability,” says Claudio Cáceres, who is also an professor at the Universidad Andrés Bello.
The astronomer adds that in the two previous cases, the most plausible scenarios correspond to objects that block the star’s light by crossing the line of sight while orbiting it, such as a planet that hosts a rings system or some group of smaller objects. “In the case of VVV-WIT-07 the scenario is very similar and, most likely, eclipsing objects would cause the observed variability. However, despite the large amount of information collected over several years, its nature remains mysterious,” Cáceres says.
From 2010 to 2018, the brightness of VVV-WIT-07 increased and decreased without an established pattern. That lack of pattern is similar to the Tabby star. “This type of discovery shows us that, despite the great advances that astronomy has made in recent decades, the development of new large-scale projects, in conjunction with the development of new technology, allows us to continue discovering new types of objects, in addition to making exponential progress in the understanding of the Universe in general. Due to the great capacity of observation of the Chilean skies, the country plays a fundamental role in this development, which brings with it the great responsibility that this opportunity entails with respect to the formation of new scientists and the use of opportunities for the development of technology and applied science. The effort that the NPF is making in this sense should be replicated in other places, in order to create people in Chile who are specialized in the development of instrumentation and advanced technology,” the scientist points out.
Juan Carlos Beamín, who was a postdoctoral researcher at the Instituto de Física y Astronomía of the Universidad de Valparaíso and a postdoctoral researcher at the Núcleo Milenio de Formación Planetaria at the time of publication, is another of the authors of the research and says that the next steps are to find other stars that present such changes in their brightness. “The LSST telescope that is being built in the IV region can be very useful for us, and also to study in detail the few objects that are known, in order to better understand and know what is really happening with these stars. For this we can use the various telescopes located in the north of our country or some of those in space,” the astronomer said.
The image that illustrates the note corresponds to an artistic representation of the Tabby Star (NASA/JPL-Caltech).