Wolf–Rayet stars in M81: detection and characterization using GTC/OSIRIS spectra and<i>HST</i>/ACS images

Gómez-González, V. M. A.; Mayya, Y. D.; Rosa-González, D.

doi:10.1093/mnras/stw1118

Cited by 37 publications

(23 citation statements)

References 36 publications

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“…The tilt angles θ were limited to |θ| < 45 • to ensure a robust sky subtraction and wavelength calibration. The spectroscopic data reduction was carried out using the OSIRIS-GTCMOS pipeline (Gómez-González et al 2016). The main reduction steps were bias subtraction, flat-field normalization, wavelength calibration, and sky subtraction.…”

Section: Observationsmentioning

confidence: 99%

Evolution of galaxy scaling relations in clusters at 0.5 <z< 1.5

Pérez-Martínez

Ziegler²,

Dannerbauer³

et al. 2021

A&A

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Aims. We present new gas kinematic observations with the OSIRIS instrument at the GTC for galaxies in the Cl1604 cluster system at z ∼ 0.9. These observations together with a collection of other cluster samples at different epochs analyzed by our group are used to study the evolution of the Tully-Fisher, velocity-size, and specific angular momentum-stellar mass relations in dense environments over cosmic time. Methods. We used 2D and 3D spectroscopy to analyze the kinematics of our cluster galaxies and extract their maximum rotation velocities (Vmax), which were used as the common parameter in all scaling relations under scrutiny. We determined the structural parameters of our objects by fitting surface brightness profiles to the images of our objects, while stellar-mass values were computed by fitting the spectral energy distribution by making use of extensive archival optical to near-IR photometry. Our methods were consistently applied to all our cluster samples. This makes them ideal for an evolutionary comparison. Results. Up to redshift one, our cluster samples show evolutionary trends compatible with previous observational results in the field and in accordance with semianalytical models and hydrodynamical simulations concerning the Tully-Fisher and velocity-size relations. However, we find a drop of a factor ∼3 in disk sizes and an average B-band luminosity enhancement ⟨ΔMB⟩∼2 mag by z ∼ 1.5. We discuss the role that different cluster-specific interactions may play in producing this observational result. In addition, we find that our intermediate-to-high redshift cluster galaxies follow parallel sequences with respect to the local specific angular momentum to stellar mass relation, although they display lower specific angular momentum values than field samples at similar redshifts. This may be explained by the stronger interacting nature of dense environments in comparison with the field.

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Section: Observationsmentioning

confidence: 99%

Evolution of galaxy scaling relations in clusters at 0.5 <z< 1.5

Pérez-Martínez

Ziegler²,

Dannerbauer³

et al. 2021

A&A

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“…The data were reduced with the gtcmos iraf 1 pipeline de- veloped by Divakara Mayya (Gómez-González et al 2016). The script transforms the raw CCD images into mosaics, performs the bias correction and wavelength calibration.…”

Section: Observations Data Reduction and Preliminary Analysismentioning

confidence: 99%

Ongoing star formation at the outskirts of Sextans A: Spectroscopic detection of early-O type stars.

García

Herrero

Najarro

et al. 2019

Monthly Notices of the Royal Astronomical Society

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With both nebular-and stellar-derived abundances of 1/10 Z ⊙ and low foreground extinction, Sextans A is a prime candidate to replace the Small Magellanic Cloud as reservoir of metal-poor massive stars and reference to study the metal-poor Universe. We report the discovery of two early-O type stars in Sextans A, the earliest O-stars with metallicity <1/7 Z ⊙ known to date, and two additional O9 stars. Colour-excess estimates towards individual targets, enabled by spectral typing, manifest that internal reddening is neither uniform nor negligible. The four targets define a new region of star formation far from the opticallybrightest centre of the galaxy and from its conspicuous H ii shells, but not devoid of neutral hydrogen. In fact, we detect a spatial correlation between OB-stars and H i in Sextans A and other dIrr's that leads us to propose that the neutral phase may be fundamental to star formation in low-density environments. According to the existing evidence at least two of the targets formed in isolation, thus suggestive of an stochastic sampling of the initial mass function that would enable low-mass galaxies like Sextans A to form very massive stars. The discovery of these four stars provide spatially-resolved, spectroscopic confirmation of recent findings suggesting that dwarf galaxies can sustain star formation despite the low density of the gas phase.

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“…As the duration of this transition phase is very short (∼ 1 Myr), they are hard to find (Crowther et al 1995). Only about a dozen of transition type stars are currently known in the Milky Way, the LMC, the SMC, IC10, NGC 1313, M31, M33 and M81 (Morgan & Good 1987;Conti & Massey 1989;Schild et al 1990;Breysacher et al 1999;Crowther et al 2003;Hadfield & Crowther 2007;Massey et al 2014;Shara et al 2016;Gómez-González et al 2016). We note that no WN/C star in M31 has been known to us until the first one was detected by Shara et al (2016).…”

Section: Introductionmentioning

confidence: 81%

A New Transition Wolf-Rayet WN/C Star in the Milky Way

Zhang,

Todt,

et al. 2020

Preprint

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We report the discovery of a new transition type Wolf-Rayet (WR) WN/C star in the Galaxy. According to its coordinates (R.A., Dec) J2000 = 18 h 51 m 39. s 7, −05 • 34 ′ 51. ′′ 1, and the distance (7.11 +1.56 −1.22 kpc away from Earth) inferred from the second Gaia data release, it's found that WR 121-16 is located in the Far 3 kpc Arm, and it is 3.75 kpc away from the Galactic Center. The optical spectra obtained by the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and the 2.16 m telescope, both located at the Xinglong Observatory in China, indicate that this is a WR star of the transitional WN7o/WC subtype. A current stellar mass of about 7.1 +1.7 −1.1 M ⊙ , a mass-loss rate of Ṁ = 10 −4.97 +0.16 −0.20 M ⊙ yr −1 , a bolometric luminosity of log L/L ⊙ = 4.88 +0.17 −0.15 , and a stellar temperature of T * = 47 +9 −5 kK are derived, by fitting the observed spectrum with a specific Potsdam Wolf-Rayet (PoWR) model. The magnitude in V -band varies between 13.95 and 14.14 mag, while no period is found. Based on the optical spectra, the time domain data, and the indices of the astrometric solution of the Gaia data, WR 121-16 is likely a transitional WN/C single star rather than a WN+WC binary.

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Wolf–Rayet stars in M81: detection and characterization using GTC/OSIRIS spectra andHST/ACS images

Cited by 37 publications

References 36 publications

Evolution of galaxy scaling relations in clusters at 0.5 <z< 1.5

Evolution of galaxy scaling relations in clusters at 0.5 <z< 1.5

Ongoing star formation at the outskirts of Sextans A: Spectroscopic detection of early-O type stars.

A New Transition Wolf-Rayet WN/C Star in the Milky Way

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