Orbital and Physical Properties of the sigma Ori Aa, Ab, B Triple System.

Figure caption: Zooming into the core of the sigma Orionis cluster, from the Orion constellation to the sigma Ori Aa,Ab,B triple system. Image credits: Gabriel Pérez (SMM, IAC), Sergio Simón-Díaz (IAC/ULL) and J.A. Caballero (CAB/CSIC), from a composition
Figure caption: Zooming into the core of the sigma Orionis cluster, from the Orion constellation to the sigma Ori Aa,Ab,B triple system. Image credits: Gabriel Pérez (SMM, IAC), Sergio Simón-Díaz (IAC/ULL) and J.A. Caballero (CAB/CSIC), from a composition
Advertised on
References
2015 ApJ 799 169

We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus other available information on photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the σ Ori Aa, Ab pair. We provided indirect arguments indicating that σ Ori B is a fast-rotating early B dwarf. The FASTWIND+BONNSAI analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while σ Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the σ Orionis cluster, at 3 ± 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the σ Orionis cluster, the interpretation of the strong X-ray emission detected for σ Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects.

News type
Research news

It may interest you

  • Hertzsprung–Russel diagram blue supergiants
    Research news
    Challenging the theoretically predicted mass-loss rate increase of blue supergiants in the bi-stability region of the stellar winds
    The properties of blue supergiants are key for constraining the end of the main sequence phase, a phase during which massive stars spend most of their lifetimes. The lack of fast-rotating stars below 21.000K, a temperature around which stellar winds change in behaviour, has been proposed to be caused by enhanced mass-loss rates, which would spin down the star. Alternatively, the lack of fast-rotating stars may be the result of stars reaching the end of the main sequence. Here, we combine newly derived estimates of photospheric and wind parameters, wind terminal velocities from the literature
    Advertised on
  • Asteroid reflectance spectra from Gaia DR3
    Research news
    Asteroid reflectance spectra from Gaia DR3: Near-UV in primitive asteroids
    Asteroids are the remnants of the planetary formation in the Solar System and so, their study helps us to understand the conditions during the early stages of the formation of our planetary system. Among asteroids, those classified as primitives present similar spectra to that of carbonaceous chondrites, i.e., they are rich in carbon and organic compounds and silicates altered by the presence of liquid water (phyllosilicates). Primitive asteroids are well characterized in various wavelength regions, showing their most diagnostic feature at 3μm. However, there is a lack of information in the
    Advertised on
  • log_n_c_n_o_bsgs_ann_groups7
    Research news
    The origin of the brightest stars in any Galaxy lies in stellar mergers
    Massive stars, those over ten times heavier than our Sun, are the conduits of most elements of the periodic table and drive the morphological and chemical makeup of their host galaxies. Yet the origin of the most luminous and hottest stars among them, called 'blue supergiants', has been debated for many decades. Blue supergiants are strange stars. First, they are observed in large numbers, despite conventional stellar physics expecting them to live only briefly. Second, they are typically found alone, despite most massive stars being born with companions. Third, the majority of them harbour
    Advertised on