The Importance of the Recent MAXI X-ray Nova Discovery

(Originally posted October 27, 2010)

About a month ago, I received a really interesting press release from JAXA about the discovery of a new X-ray nova via the International Space Station Monitor of All-sky X‑ray Image (MAXI) instrument. One of the first things I did was contact colleagues in NASA’s Science Mission Directorate to ask what they thought of the finding. I have a background in Earth science, not space science, so I was interested in their point of view on what sounded like an exciting discovery. They were full of additional questions and wanted more information. So we contacted our Japanese associates to better understand the discovery and impacts.

Of particular assistance was Masaru Matsuoka, the JAXA lead member on the MAXI team. I wanted to know if this was a new X-ray nova occurring or an existing one that was missed in previous surveys. He responded that the X-ray nova discovered by MAXI was a new X-ray source, not previously identified or catalogued. In other words, he continued, this nova occurred as an outburst in this location for the first time, which is why RIKEN named it MAXI J1659-152.

Matsuoka-san added that what makes this X-ray source especially interesting is that it is the type that likely has a black hole at its center. A new find like this is made once or twice a year overall. This is the first new source discovered by MAXI.


              Comparison of all-sky images before and after September 25 when the nova was found.
(Image courtesy of JAXA press release)

The MAXI instrument was able to locate this recent find by using two slit cameras (a gas slit camera and a solid-state camera) to continuously monitor astronomical X-ray objects. MAXI performs an entire sky scan once every rotation of the space station around the Earth. Mounted to the exterior of the KIBO module, MAXI has open access to the space environment where it identified the X-ray nova event. The information from the sky scans downloads to RIKEN, where the MAXI team disseminates data to scientists around the globe for study.

This is a promising result from the operations of this instrument. The more X-ray sources we find and study, the better knowledge astronomers can gain about the nature of black holes and their distribution in the universe.

Julie A. Robinson, Ph.D.
International Space Station Program Scientist


(Update: Originally posted December 3, 2010)

On October 17, 2010, MAXI discovered yet another new X-ray nova, located in Centaurs. Since the emerging nova was dark, scientists continued to collect data while waiting for it to brighten. They announced the discovery on October 20, 2010 and named it MAXI J1409-619. The nova was confirmed as an unprecedented bright X-ray source, after NASA’s astronomical satellite, Swift, conducted an urgent target-of-opportunity observation. This nova is either a black hole or a neutron star with a companion star of a massive star existing over several ten thousands light-years.

Images of areas of 10 degrees in radius around the nova MAXI J1409-619. A celestial body that was not observed on Oct. 12 shone bright on the 17th. Right ascension 14 hr. 09 min. 2 sec., Declination -61 deg. 57 min. The detailed X-ray image shot by the Swift satellite. An unknown bright new celestial body was seen in the brighter part (0.2 degrees in radius) observed by the MAXI.

(Images courtesy of JAXA Press Release)