The upper panel displays the trace spectrum of XZ UMa in the Fe I λ4957 region. In the bottom panel, the circle is the observed spectrum at orbital phase 0.256 (BJD 2,459,554.2000), and the blue, green, and red lines represent the principal component composite spectrum and its convolved spectrum, respectively. credit: arXiv (2023). DOI: 10.48550/arxiv.2312.13642
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The upper panel displays the trace spectrum of XZ UMa in the Fe I λ4957 region. In the bottom panel, the circle is the observed spectrum at orbital phase 0.256 (BJD 2,459,554.2000), and the blue, green, and red lines represent the principal component composite spectrum and its convolved spectrum, respectively. credit: arXiv (2023). DOI: 10.48550/arxiv.2312.13642
Astronomers conducted photometric and spectroscopic studies of the Algol-type binary star known as XZ Ursa Majoris (abbreviated XZ UMa).Research results published in papers published December 21st on preprint server arXivindicating that this binary is a pulsating system.
Algol-type binaries are a class of eclipsing binaries related to the prototype member of this class, known as the Beta Perse star or Algol. These are semi-separated systems in which the less massive component transfers mass to the more massive component by filling the Roche lobe, causing a loss of mass and angular momentum.
XZ UMa is a semi-discrete Algol type system with spectral type A5+F9. The orbital period is approximately 1.22 days, and the effective temperature of the main components of this system is estimated to be approximately 7,766 K.
Previous observations suggest that XZ UMa exhibits pulsations. However, no evidence has been found to support this hypothesis. Some studies have also found that XZ UMa’s orbital period has changed over the years, indicating the presence of a third object in the system with about half the mass of the Sun.
To test these theories, a team of astronomers led by Jae Woo Lee of the Korea Institute of Astronomy and Space Science in Daejeon, South Korea, conducted high-resolution spectroscopic observations with the Bohyeonsan Observatory’s Echelle spectrometer and the 1.8-XZ UMa. carried out. His m telescope at Bokenzan Optical Astronomical Observatory (BOAO). This study was complemented by photometric data from NASA’s Transiting Exoplanet Survey Satellite (TESS).
Lee’s team was able to identify at least six possible independent pulsation frequencies for the XZ UMa. The period and constant of these pulsations were determined to be 28–37 min and 0.013–0.016 days, respectively. The high-frequency pulsation orbit period ratio was found to be between 0.016 and 0.021, suggesting that the host star XZ UMa A is a Delta Scuti pulsator.
The study found that XZ UMa A has a rotational speed of about 80 km/s, suggesting that it is likely currently in a supersynchronous state. The effective temperature of XZ UMa A was determined to be 7,940 K and the metallicity was found to be at the -0.15 level. The host star was found to be about 76% larger than the Sun, with just over twice the mass.
As for the secondary star, research shows that its mass is only 1.35 solar masses, even though its radius is about 2.48 solar radii. The effective temperature of XZ UMa B is estimated to be 5,162 K.
Summarizing their results, the authors conclude that the XZ UMa Delta Scuti eclipsing binary is in a semi-disjunct configuration.
For more information:
Jae Woo Lee et al., Absolute characteristics of the oscillating solar eclipse Algol XZ Ursa Major, arXiv (2023). DOI: 10.48550/arxiv.2312.13642
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