Artists rendition of a cataclysmic variable in which a white dwarf (white/blue) is accreting material from its close-by Sun-like buddy (yellow). The product forms a disk around the white dwarf till an instability causes a surge and a brilliant outburst of light, called a nova. Credit: NASA/SOFIA/L. Proudfit
Astronomers found something unique using SOFIA, the Stratospheric Observatory for Infrared Astronomy. They found a brand-new type of stellar outburst that had never been seen before in the kind of system under study. Through some creative scientific detective work, the astronomers were able to determine the qualities that made this outburst different, putting it in its own new classification.
In what is called a classical nova, a white dwarf– the thick residue of a star in the last phase of its evolution– gathers product from a close-by Sun-like companion star. The material absorbed from the buddy star builds up on the surface of the white dwarf, until severe pressures and densities trigger a nuclear explosion, ejecting the material from the surface of the white dwarf.
The product forms a disk around the white dwarf up until an instability triggers a surge and a brilliant outburst of light, known as a nova. In what is called a classical nova, a white dwarf– the thick residue of a star in the last stage of its advancement– gathers product from a nearby Sun-like buddy star. In contrast, a dwarf nova happens in the exact same kind of system as a classical nova, but for a various reason. As far as we understand, the longest dwarf nova cases have been around 100 days. Such combinations of outbursts are frequently referred to as combination novae and have actually been observed to take place in systems that include a huge companion and a white dwarf star, but theres no proof of a huge star in V1047 Cen– if there were, we would be able to see it.
Comprised of a Boeing 747SP aircraft modified to accommodate a 2.5 meter gyro-stabilized telescope, SOFIA was the biggest airborne observatory worldwide. From high in Earths atmosphere, the mission could make observations that are difficult for even the biggest ground-based telescopes on the greatest mountain summits. SOFIA was a joint program between NASA and the German Aerospace Center (DLR).
On the other hand, a dwarf nova takes place in the very same type of system as a classical nova, however for a different factor. This type of nova takes place when the disc around the white dwarf ends up being unstable triggering an outburst that is much less effective and intense than a classical nova. These outbursts last only a few days, but take place more regularly.
The catastrophic variable SOFIA observed– V1047 Cen, a white dwarf, and its Sun-like buddy– emerged as a classical nova in 2005 (Nova Centauri 2005). 14 years later on, in April 2019, the system gradually began to re-brighten.
On days 88 and 89 after V1047 Cen started to brighten once again, a team of scientists led by Dr. Elias Aydi, an astronomer at Michigan State University, used the FORCAST electronic camera aboard SOFIA to analyze the system. They at first thought the re-brightening was indicative of a dwarf nova, however, unlike dwarf novae, this one kept opting for quite a while.
” The thing about dwarf novae is they normally occur reasonably rapidly. Most of them tend to rise to peak quickly and after that decline rapidly, they dont invest a great deal of time at the peak,” Aydi said. As far as we understand, the longest dwarf nova cases have actually been around 100 days. V1047 Cen went on for 400. “If this was a dwarf nova, it would be a record-breaking one.”
An Armstrong F/A -18 flying security and photo chase for NASAs SOFIA 747. SOFIA accomplished full operational capability in 2014 and concluded its final science flight on September 29, 2022. Credit: NASA/ Jim Ross
Comprehending the temperature of the gas around the system is normally an essential hint regarding what is going on. In this case, the private investigators used the SOFIA spectra to reveal the temperature, which revealed heating as an outcome of the outburst, assisting to show it was more than a typical dwarf nova.
With features inconsistent with both classical novae and dwarf novae, the researchers tried to come up with an alternate explanation for this unusual event.
“We resembled, Theres something truly intriguing here, and we need to attempt to discuss it,” Aydi said.
Supplementing the SOFIA information, the group of astronomers likewise performed observations using almost a dozen other instruments, covering much of V1047 Cens 400-day event. Taken together, the information began to make more sense, and they understood they had come throughout something distinct– a brand-new kind of excellent outburst that had never been seen prior to in this type of system. The discovery uncovers brand-new situations that can occur in these types of cataclysmic variables.
“Its certainly not a classical nova, however definitely something more than a dwarf nova. Its something in between, and likely a combination of various processes or outbursts,” Aydi said.
Such combinations of outbursts are frequently referred to as mix novae and have been observed to occur in systems that feature a white dwarf and a huge buddy star, however theres no evidence of a huge star in V1047 Cen– if there were, we would be able to see it. Rather of a huge star, the white dwarf in V1047 Cen has a Sun-like companion. In addition, the observed qualities of the outburst are not exactly like those seen in combination novae. This makes the 2019 outburst of V1047 Cen rather an exotic one– the very first of its kind ever to be seen in a catastrophic variable system that has actually gone through a current classical nova eruption.
Learning what caused this outburst is essential to understanding V1047 Cen, and potentially other similarly uncommon outbursts that may be found in the future. Among the main actions will be figuring out how quickly the white dwarf and its Sun-like buddy are orbiting their center of gravity, which will require additional observations.
SOFIA was a joint project of NASA and the German Space Agency at DLR. DLR provided the telescope, arranged aircraft upkeep, and other support for the mission. NASAs Ames Research Center in Californias Silicon Valley managed the SOFIA mission, science, and program operations in cooperation with the Universities Space Research Association, headquartered in Columbia, Maryland, and the German SOFIA Institute at the University of Stuttgart. The airplane was kept and run by NASAs Armstrong Flight Research Center Building 703, in Palmdale, California. SOFIA accomplished complete operational capability in 2014 and concluded its final science flight on September 29, 2022.