Key Science Case: Massive Stars
Additional science cases:
- BlueMUSE will provide systematic maps of stellar properties and chemical compositions for very massive clusters in the Milky Way and local group galaxies, such as NGC 2070 in the Large Magellanic Cloud. Its unique wavelength coverage in the blue range (4000 – 5000 Å) is essential for accessing key diagnostic lines, such as [OII], [SiII/III/IV], and [NII]. Since hot stars are intrinsically blue, BlueMUSE’s wavelength coverage aligns closely with the peak of their spectral energy distributions, offering significant advantages over MUSE. Additionally, the large spectral resolution of BlueMUSE will enable a more detailed exploration of the kinematics and the presence of binary within these environments.
Figure 1. Three colour image of the star-forming region N180 in the Large Magellanic Cloud, imaged with MUSE as a 64-pointing mosaic (8’x8’). The red, green, and blue colours are [SII]6717, Hα, and [OIII]5007, respectively.
- In our Galaxy and within the Local Group BlueMUSE will be able to map physical properties at the smallest physical scales (sub-parsec). The aim of these studies is to understand the interplay between stellar feedback and the immediate surrounding medium. At intermediate distances (2 and 10 Mpc), the panoramic BlueMUSE field of view will enable to map the diffuse ionised gas component, physical conditions, abundances, and kinematics of the ionised gas in large and diverse samples of resolved nebulae. The wavelength range covered by BlueMUSE will provide emission lines sensitive to gas densities (e.g., [OII] λλ3729, 3726, [Cl III] λλ5518, 5535, [ArIV] λλ4740,4711), temperature ([OIII] λλ4363, 4958, 5007; [NeIII] λλ3343, 3968, 3869) and enable direct abundance measurements. These will be fundamental to study the mixing time scales across different galactic environments. The blue range will also cover the [NeV] λλ3426 line, used as AGN diagnostic. The increased spectral resolution will enable a better derivation of the kinematics of the ionised gas and stellar components, important to understand the 3D structure of disk galaxies.
Figure 2. Comparison of extracted parameters from mock BlueMUSE and MUSE-AO data cubes of a 30Dor-like system. Both data cubes were simulated by BlueSi software [LINK], accounting for all instrumental properties, including the rectangular spaxels for BlueMUSE. Observing conditions were the same, with a natural seeing of FWHM=0.8″ (for BlueMUSE) and an GLAO correction to PSF FWHM=0.6″ for MUSE. The data cubes were analysed in the standard manner (e.g. using PampelMUSE to extract stellar spectra). The extracted values were compared with the input values. Left: histogram of the difference between extracted and input the surface gravity. Right: histogram of the difference between extracted and input temperature. the increase precision of the BlueMUSE measurements is due to the higher spectral resolution and a larger number of lines in the blue part of the spectra of massive stars.
- The spatial information provided by an IFS is essential for disentangling individual spectra in dense stellar environments, such as globular clusters (GCs). MUSE allowed for the retrieval of tens of thousands of spectra per cluster, enabling detailed studies of their chemical compositions and dynamics. Access to the blue-visible and near-UV wavelength regions with BlueMUSE will uncover critical spectral features that are highly sensitive to subtle abundance differences among distinct stellar populations within GCs. Moreover, the increased spectral resolution will offer enhanced precision in measuring radial velocities, facilitating the detection of binary systems and probing stellar dynamics in the vicinity of intermediate-mass black holes.
- Due to their faintness, Ultra Faint Dwarf galaxies (UFDs) are only found as satellites of the dominant galaxies in the Local Group, but their nature offers unique laboratories to study the properties of dark matte As the amount of baryons in these galaxies is rather small, one expects their star formation histories to be simple and lacking strong stellar feedback episodes. A consequence is that the dark matter (density) profiles are expected to be closely related to those of dark-matter-only simulations, making UFDs systems where the difference between intrinsic properties of dark matter can be studied, as well as potentially determine the nature of dark matter (e.g., is it “cold”, “warm” or “fuzzy”) and whether it is collision-less or self-interacting.
Figure 3. A typical coma spectrum of comet 9P/Tempel 1 (Meech et al. 2011). The BlueMUSE coverage (blue-shaded region) covers multiple radicals like CN, C2, and C3 and group transitions.
- Large field of view IFS have proven extremely useful to detect faint activity levels in comets, helping us understand how their activity evolves with varying distances from the Sun. A number of radicals are observable in the blue part of the optical range (e.g., CN and C3). BlueMUSE will provide an in-depth insight into the production mechanisms of species in the coma of comets, as well as their activity. BlueMUSE will also offer unique opportunities for the observation of interstellar objects, which formed in other planetary systems and crossing pass through our own solar system.