MEGARA-GTC stellar spectral library: I

García-Vargas, M. L.; Carrasco, E.; Mollá, M.; Paz, A. Gil de; Berlanas, S. R.; Cardiel, N.; Gómez-Álvarez, P.; Gallego, J.; Iglésias-Páramo, J.; Cedazo, R.; Pascual, S.; Castillo-Morales, Á.; Pérez-Calpena, A.; Martínez-Delgado, I.

doi:10.1093/mnras/staa126

Cited by 8 publications

(1 citation statement)

References 74 publications

(71 reference statements)

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“…There are several commonly used designs for such spectrographs: image slicers that deliver rows of long-slit spectra spaced exactly by the slit width, which are then subdivided into one-dimensional spectra in each spaxel, examples are MUSE at the VLT 1 or WiFES at the 2.3m Siding Spring observatory. 2 Alternatively, IFUs use microlenses or fibre-bundles to directly obtain a 1D spectrum in each spaxel after passing through dispersing optics, examples are MEGARA at the 10.4m GTC 3 or the now decommissioned VIMOS spectrograph at the VLT. 4 For reasons of efficiency, the most widely used concept currently are image slicers.…”

Section: Introductionmentioning

confidence: 99%

EIFIS: a modular extreme integral field spectrograph for the 10.4m GTC

Thöne¹,

Postigo²,

Vargas³

et al. 2022

Preprint

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EIFIS (Extreme Integral FIeld Spectrograph) is a modular integral field spectrograph, based on image slicers, and makes use of new, large format detectors. The concept is thought to cover the largest possible field of view while producing spectroscopy over the complete optical range (3 000 -10 000 Å) at a medium resolving power of ∼2400. In the optimal concept, each module covers a field of view of 38" x 38" with 0.3" spaxels, which is fed into a double spectrograph with common collimator optics. The blue arm covers the spectral range between 3000 and 5600 Å and the red arm between 5400 and 10100 Å, allowing for an overlap range. The spectra are imaged onto 9.2k x 9.2k detectors using a double pseudoslit. The proposed design for the 10.4m Gran Telescopio Canarias uses a total of 6 such modules to cover a total of 2.43 square arcminutes. Here we will present the conceptual design of the instrument and a feasibility study of the optical and mechanical design of the spectrographs. We discuss the limitations and alternative designs and its potential to produce leading edge science in the era of extremely large telescopes and the James Webb Space Telescope.

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Section: Introductionmentioning

confidence: 99%

EIFIS: a modular extreme integral field spectrograph for the 10.4m GTC

Thöne¹,

Postigo²,

Vargas³

et al. 2022

Preprint

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Once in a blue stream

Martínez-Delgado,

Roca-Fàbrega,

Gil de Paz

et al. 2024

A&A

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Aims. In this work we study the striking case of a narrow blue stream with a possible globular cluster-like progenitor around the NGC 7241 galaxy and its foreground dwarf companion. We want to figure out if the stream was generated by tidal interaction with NGC 7241 or if it first interacted with the foreground dwarf companion and later both fell together toward NGC 7241. Methods. We used four sets of observations, including a follow-up spectroscopic study of this stream based on data taken with the MEGARA instrument at the 10.4 m Gran Telescopio Canarias using the integral field spectroscopy mode, the Mount Lemmon 0.80 m telescope, the Telescopio Nazionale Galileo, the DESI Imaging Legacy surveys, and GALEX archival data. We also used high-resolution zoomed-in cosmological simulations. Results. Our data suggest that the compact object we detected in the stream is a foreground Milky Way halo star. Near this compact object we detect emission lines overlapping a less compact, bluer, and fainter blob of the stream that is clearly visible in both ultraviolet and optical deep images. From its heliocentric systemic radial velocity derived from the [O III]λ5007 Å lines (Vsyst = 1548.58 ± 1.80 km s−1) and new UV and optical broadband photometry, we conclude that this overdensity could be the actual core of the stream, with an absolute magnitude of Mg ∼ −10 and a g − r = 0.08 ± 0.11, consistent with a remnant of a low-mass dwarf satellite undergoing a current episode of star formation. From the width of the stream and assuming a circular orbit, we calculate that the progenitor mass can be typical of a dwarf galaxy, but it could also be substantially lower if the stream is on a very radial orbit or if it was created by tidal interaction with the companion dwarf instead of with NGC 7241. These estimates also suggest that this is one of the lowest mass streams detected to date beyond the Local Group. Finally, we find that blue stellar streams containing star formation regions are commonly predicted by high-resolution cosmological simulations of galaxies lighter than the Milky Way. This scenario is consistent with the processes explaining the bursty star formation history of some dwarf satellites, which are followed by a gas depletion and a fast quenching once they enter within the virial radius of their host galaxies for the first time. Thus, it is likely that the stream’s progenitor is undergoing a star formation burst comparable to those that have shaped the star formation history of several Local Group dwarfs in the last few gigayears.

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MEGARA-GTC stellar spectral library – II. MEGASTAR first release

Carrasco

Mollá

García-Vargas

et al. 2020

Monthly Notices of the Royal Astronomical Society

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MEGARA is an optical integral field and multi-object fibre-based spectrograph for the 10.4m Gran Telescopio CANARIAS that offers medium to high spectral resolutions (FWHM) of R ≃ 6000, 12000, 20000. Commissioned at the telescope in 2017, it started operation as a common-user instrument in 2018. We are creating an instrument-oriented empirical spectral library from MEGARA-GTC stars observations, MEGASTAR, crucial for the correct interpretation of MEGARA data. This piece of work describes the content of the first release of MEGASTAR, formed by the spectra of 414 stars observed with R ≃ 20000 in the spectral intervals 6420 – 6790 Å and 8370 – 8885 Å, and obtained with a continuum average signal to noise ratio around 260. We describe the release sample, the observations, the data reduction procedure and the MEGASTAR database. Additionally, we include in Appendix A, an atlas with the complete set of 838 spectra of this first release of the MEGASTAR catalogue.

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MEGARA-GTC stellar spectral library: I

Cited by 8 publications

References 74 publications

EIFIS: a modular extreme integral field spectrograph for the 10.4m GTC

EIFIS: a modular extreme integral field spectrograph for the 10.4m GTC

Once in a blue stream

MEGARA-GTC stellar spectral library – II. MEGASTAR first release

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