Wednesday 16 April 2025
A team of astronomers has shed new light on a mysterious binary star system, providing insights into the nature of interstellar extinction and the properties of the system itself.
Located about 1,800 parsecs away in the constellation Cassiopeia, the binary star system MWC 148 is comprised of a Be star and an unknown compact object. This unusual pairing has been observed to emit gamma rays above 100 GeV, making it a rare and fascinating subject for study.
To better understand this system, researchers analyzed high-resolution optical spectra obtained from Observatoire de Haute Provence and Rozhen Observatory. By measuring the equivalent widths of seven diffuse interstellar bands (DIBs), they were able to estimate the interstellar extinction towards MWC 148 at EB-V = 0.85 ± 0.08.
This value is significant because it suggests that the interstellar medium in this direction may be peculiar, meaning that our current understanding of dust and gas in the galaxy may not fully apply here. Alternatively, some or all of the DIBs observed in MWC 148’s spectra could be formed in the circumstellar environment rather than in the interstellar medium.
The researchers used two different methods to calculate EB-V, one based on ordinary least squares (OLS) and another using orthogonal distance regression (ODR). While both methods yielded similar results, the ODR method produced values about 10% larger. This discrepancy highlights the complexities involved in estimating extinction and underscores the importance of considering multiple approaches.
The findings also provide insight into the properties of MWC 148 itself. By analyzing the light curves of this binary system, researchers have observed a modulation of the very high-energy gamma-ray fluxes with an orbital period of about 317 days. This is consistent with previous observations and suggests that the compact object is likely either a neutron star or black hole.
The study’s results demonstrate the importance of continued research into the properties of binary star systems like MWC 148. By better understanding these complex systems, scientists can gain valuable insights into astrophysical phenomena and improve our comprehension of the universe as a whole.
In their analysis, the researchers employed a range of techniques to extract meaningful information from the observed spectra. This included the use of IRAF’s splot routine to measure the equivalent widths of the DIBs and the application of OLS and ODR methods to calculate EB-V.
Cite this article: “Uncovering the Cosmic Fog: Researchers Pinpoint Interstellar Extinction Toward MWC 148”, The Science Archive, 2025.
Here Are The 10 Keywords: Astronomy, Binary Star System, Gamma Rays, Interstellar Extinction, Cassiopeia, Be Stars, Compact Objects, Neutron Stars, Black Holes, Astrophysics
