We have selected the Galactic HII region M43, a close-by apparently spherical nebula ionized by a single star (HD37061, B0.5V) to investigate several topics of recent interest in the field of HII regions and massive stars. We perform a combined, comprehensive study of the nebula and its ionizing star by using as many observational constraints as possible. For this study we collected a set of high-quality observations, including the optical spectrum of HD3706, along with nebular optical imaging and long-slit spatially resolved spectroscopy. On the one hand, we have carried out a quantitative spectroscopic analysis of the ionizing star from which we have determined the stellar parameters of HD37061 and the total number of ionizing photons emitted by the star; on the other hand, we have done a empirical analysis of the nebular images and spectroscopy from which we have find observational evidence of scattered light from the Huygens region (the brightest part of the Orion nebula) in the M43 region. We show the importance of an adequate correction of this scattered light in both the imagery and spectroscopic observations of M43 in accurately determining the total nebular Halpha luminosity, the nebular physical conditions. and chemical abundances. We have computed total abundances for three of the analyzed elements (O, S, and N), directly from observable ions (no ionization correction factors are needed). The comparison of these abundances with those derived from the spectrum of the Orion nebula indicates the importance of the atomic data and, specially in the case of M42, the considered ionization correction factors.
Advertised on
It may interest you
-
Measuring galaxy sizes is essential for understanding how they were formed and evolved across time. However, traditional methods based on l ight concentration or isophotal densities often lack a clear physical meaning. A recent study from Trujillo+20 explores a more physically motivated definition: the radius R 1, where the stellar surface density falls to 1 solar masses per parsec square —roughly the threshold for gas to form stars in galaxies like the Milky Way. In this work, Arjona-Gálvez+25 uses over 1,000 galaxies from several state-of-the-art cosmological simulations (AURIGA, HESTIAAdvertised on -
The TESS (Transiting Exoplanet Survey Satellite) mission has discovered many exoplanet candidates that need to be confirmed and characterized from the ground. One of them orbits Ross 176, a K-type dwarf star, where we have identified a promising hot “water-world” candidate. Using spectroscopic observations with the CARMENES instrument, we confirmed the planetary nature of the signal detected by TESS and estimated the planet’s mass. To improve the analysis, we applied an advanced statistical method called Gaussian Process, which allowed us to separate the star’s own variability (quite strongAdvertised on -
O ne of the key challenges in astronomy is to measure accurate distances to celestial objects. Knowing distances is crucial since it allows us to measure physical properties such as size, mass and luminosity. Since we can’t go out and use a tape-measure, a range of different approaches have been developed. Many of these approaches rely on using “standard candles”. Standard candles are objects (for example stars or supernovae) for which we know their intrinsic ”true” brightness. Once we know this, then their observed brightness compared to their intrinsic brightness gives us a distance to theAdvertised on