PRINT A 3D NOVA

For decades, astronomers have known about irregular outbursts from the double star system V745 Sco, which is located about 25,000 light years from Earth. Astronomers were caught by surprise when previous outbursts from this system were seen in 1937 and 1989. When the system erupted on February 6, 2014, however, scientists were ready to observe the event with a suite of telescopes including NASA's Chandra X-ray Observatory.

This optical image of V745 Sco (also known as Nova 1937) was taken on February 6, 2014 from Siding Springs Observatory in Australia by S. O'Conner (OCN, St. Georges, Bermuda). (Credit: S. O'Connor (OCN, St. Georges, Bermuda)

V745 Sco is a binary star system that consists of a red giant star an a white dwarf locked together by gravity. These two stellar objects orbit so closely around one another that the outer layers of the red giant are pulled away by the intense gravitational force of the white dwarf. This material gradually falls onto the surface of the white dwarf. Over time, enough material may accumulate on the white dwarf to trigger a colossal thermonuclear explosion, causing a dramatic brightening of the binary called a nova. Astronomers saw V745 Sco fade by a factor of a thousand in optical light over the course of about 9 days.

Astronomers observed V745 Sco with Chandra a little over two weeks after the 2014 outburst. Their key finding was it appeared that most of the material ejected by the explosion was moving towards us. To explain this, a team of scientists from the INAF-Osservatorio Astronomico di Palermo, the University of Palermo, and the Harvard-Smithsonian Center for Astrophysics constructed a three-dimensional (3D) computer model of the explosion, and adjusted the model until it explained the observations. In this model they included a large disk of cool gas around the equator of the binary caused by the white dwarf pulling on a wind of gas streaming away from the red giant.

The computer calculations showed that the nova explosion's blast wave and ejected material were likely concentrated along the north and south poles of the binary system. This shape was caused by the blast wave slamming into the disk of cool gas around the binary. This interaction caused the blast wave and ejected material to slow down along the direction of this disk and produce an expanding ring of hot, X-ray emitting gas. X-rays from the material moving away from us were mostly absorbed and blocked by the material moving towards Earth, explaining why it appeared that most of the material was moving towards us.

In the figure (pictured above) showing the new 3D model of the explosion, the blast wave is yellow, the mass ejected by the explosion is purple, and the disk of cooler material, which is mostly untouched by the effects of the blast wave, is blue. The cavity visible on the left side of the ejected material is the result of the debris from the white dwarf's surface being slowed down as it strikes the red giant.

An extraordinary amount of energy was released during the explosion, equivalent to about 10 million trillion hydrogen bombs. The authors estimate that material weighing about one tenth of the Earth's mass was ejected.

While this stellar-sized belch was impressive, the amount of mass ejected was still far smaller than the amount what scientists calculate is needed to trigger the explosion. This means that despite the recurrent explosions, a substantial amount of material is accumulating on the surface of the white dwarf. If enough material accumulates, the white dwarf could undergo a thermonuclear explosion and be completely destroyed. Astronomers use these so-called Type Ia supernovas as cosmic distance markers to measure the expansion of the Universe.

The scientists were also able to determine the chemical composition of the material expelled by the nova. Their analysis of this data implies that the white dwarf is mainly composed of carbon and oxygen.

3D Printing

- Download the 3D files (Ejecta - Blast wave - Combined)
- Read the brief instructions below
- Select the 3D printer of your choice.

A 3D print of the model was also created (pictured below). This 3D print was simplified and printed in two parts, the blast wave (shown here in grey) and the ejected material (shown here in yellow). Also shown below is a combined print of the blast wave and ejected material (upper right).

Credit: S. Orlando (INAF-Osservatorio Astro. di Palermo) & NASA/CXC/SAO/A.Jubett et al.

To print your own copy of V745 Sco, select the 3D printer of your choice and scale to the desired size (shown here printed at 4” x 3”). The blast wave took about 24 hours to print on the Ultimaker 3 (alternatively, it took 9.5 hours to print on a DaVinci 3D printer- results not pictured). The ejected material took 20 hours on the Ultimaker 3 (4 hours on a DaVinci, not shown). The combined blast wave & ejecta model printed in 2 color took 40 hours on the Ultimaker 3.

Ultimaker 3 = pro printer at 0.1 mm with PLA
DaVinci = consumer-grade printer set to “good” quality using PLA

Disclaimer: The Chandra X-ray Center does not endorse any commercial product.