NuSTAR images (3-79 keV) of the J17407 field.Credit: Ducci et al, 2023
Posted on 04/27/2023 6:32:38 AM PDT by SunkenCiv
...X-ray binaries (XRBs) are composed of a normal star or a white dwarf transferring mass onto a compact neutron star or a black hole. Based on the mass of the companion star, astronomers divide them into low-mass X-ray binaries (LMXBs) and high-mass X-ray binaries (HMXBs).
Discovered on October 9, 2004, by the International Gamma-Ray Astronomy Laboratory (INTEGRAL), IGR J17407−2808 (or J17407 for short) is an LMXB at a distance of some 12,400 light years away from the Earth. Although J17407 exhibited several peculiarly quick and strong flares in the past, it remained a poorly studied source...
NuSTAR observations conducted by Ducci's team detected J17407 in a flaring state characterized by a variability as large as three orders of magnitude on time scales of a few tens of seconds. During this state, the source exhibited several fast X-ray flares, lasting between 1 to 100 seconds and profiles with either single or multiple peaks.
The astronomers noted that the fast and strong variability of J17407 is similar to that observed in some other LMXB systems like Swift J1858.6−0814, V404 Cygni, and V4641 Sgr or in a HMXB designated A0538−66. However, they underlined that given that some fundamental characteristics of the stellar components hosted in J17407 are still unknown, it is difficult to conclude what accretion mechanisms are triggering its X-ray variability.
According to the authors of the paper, analysis of the collected data suggests that the donor star in J17407 can be either a rare K or M-type sub-subgiant or a K-type main sequence (MS) star, or sub-giant star. Therefore, the researchers propose spectroscopic observations of J17407 in optical near-infrared in order to disentangle the true nature of the donor star, noting that their recent results further support the classification of this system as an LMXB.
(Excerpt) Read more at phys.org ...
NuSTAR images (3-79 keV) of the J17407 field.Credit: Ducci et al, 2023
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Is that the actual Morse code from the song? I understand it was based on a Canadian Navy transmission that ships would reference.
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