Red Supergiants as Cosmic Abundance Probes: The Sculptor Galaxy NGC 300

Gazak, J. Zachary; Kudritzki, R. P.; Evans, C. J.; Patrick, L. R.; Davies, Ben; Bergemann, M.; Plez, B.; Bresolin, Fabio; Bender, R.; Wegner, Michael; Bonanos, A. Z.; Williams, Stephen J.

doi:10.1088/0004-637x/805/2/182

Cited by 58 publications

(86 citation statements)

References 49 publications

(86 reference statements)

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“…Even more important, Kudritzki et al (2016) have shown that their K-band radial surface profiles are also different, with NGC 300 having a strong central peak, which is instead absent in NGC 55 (see their Figure 12). The radial metallicity gradient of NGC 300 from H ii regions, studied by Bresolin et al (2009) and re-analysed by Stasińska et al (2013), is not negligible, and has a slope -0.068±0.009 dex kpc −1 (with R25=5.3 kpc), as well as the radial metallicity gradient of supergiants Gazak et al 2015). These gradients are shown in the lower panel of Figure 4.…”

Section: Discussionmentioning

confidence: 92%

NGC 55: a disc galaxy with flat abundance gradients

Magrini

Gonçalves

Vajgel

2016

Mon. Not. R. Astron. Soc.

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We present new spectroscopic observations obtained with GMOS@Gemini-S of a sample of 25 H ii regions located in NGC 55, a late-type galaxy in the nearby Sculptor group. We derive physical conditions and chemical composition through the T e -method for 18 H ii regions, and strong-line abundances for 22 H ii regions. We provide abundances of He, O, N, Ne, S, Ar, finding a substantially homogenous composition in the ionised gas of the disc of NGC 55, with no trace of radial gradients. The oxygen abundances, both derived with T e -and strong-line methods, have similar mean values and similarly small dispersions: 12+log(O/H)=8.13±0.18 dex with the former and 12+log(O/H)=8.17±0.13 dex with the latter. The average metallicities and the flat gradients agree with previous studies of smaller samples of H ii regions and there is a qualitative agreement with the blue supergiant radial gradient as well. We investigate the origin of such flat gradients comparing NGC 55 with NGC 300, its companion galaxy, which is also twin of NGC 55 in terms of mass and luminosity. We suggest that the differences in the metal distributions in the two galaxies might be related to the differences in their K-band surface density profile. The flatter profile of NGC 55 probably causes in this galaxy higher infall/outflow rates than in similar galaxies. This likely provokes a strong mixing of gas and a re-distribution of metals.

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Section: Discussionmentioning

confidence: 92%

NGC 55: a disc galaxy with flat abundance gradients

Magrini

Gonçalves

Vajgel

2016

Mon. Not. R. Astron. Soc.

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“…As noted by Gazak et al (2015), the spectral resolution of the 24 KMOS IFUs varies spatially, both for different IFUs and for individual IFUs, with a mean value of R = λ/∆λ = 4 200. Within one IFU the spectral resolution R can have a standard deviation of up to 150, and over all IFUs the standard deviation is about 300.…”

Section: Data Reductionmentioning

confidence: 95%

Asymmetric spatial distribution of subsolar metallicity stars in the Milky Way nuclear star cluster

Feldmeier-Krause

Kerzendorf

Do³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We present stellar metallicity measurements of more than 600 late-type stars in the central 10 pc of the Galactic centre. Together with our previously published KMOS data, this data set allows us to investigate, for the first time, spatial variations of the nuclear star cluster's metallicity distribution. Using the integral-field spectrograph KMOS (VLT) we observed almost half of the area enclosed by the nuclear star cluster's effective radius. We extract spectra at medium spectral resolution, and apply full spectral fitting utilising the PHOENIX library of synthetic stellar spectra. The stellar metallicities range from [M/H]=-1.25 dex to [M/H]>+0.3 dex, with most of the stars having super-solar metallicity. We are able to measure an anisotropy of the stellar metallicity distribution. In the Galactic North, the portion of sub-solar metallicity stars with [M/H]<0.0 dex is more than twice as high as in the Galactic South. One possible explanation for different fractions of sub-solar metallicity stars in different parts of the cluster is a recent merger event. We propose to test this hypothesis with high-resolution spectroscopy, and by combining the metallicity information with kinematic data.

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“…We investigate effective temperatures T eff in the range 3400-4400 K, and gravities log g between 0.0 and +1.0. For metallicity [Z], we compare the location of ULX-1 to the radial metallicity gradient as measured by Gazak et al (2015), which indicates a value of [Z] −0.1. Therefore, we explore metallicities between [Z]=0.0 to -0.25.…”

Section: The Donor Starmentioning

confidence: 99%

Discovery of a Red Supergiant Donor Star in SN2010da/NGC 300 ULX-1

Heida

Lau

Davies

et al. 2019

ApJL

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SN2010da/NGC 300 ULX-1 was first detected as a supernova impostor in May 2010 and was recently discovered to be a pulsating ultraluminous X-ray source. In this letter, we present VLT/X-shooter spectra of this source obtained in October 2018, covering the wavelength range 350-2300 nm. The J-and H-bands clearly show the presence of a red supergiant donor star that is best matched by a MARCS stellar atmosphere with T eff = 3650 − 3900 K and log(L bol /L ) = 4.25 ± 0.10, which yields a stellar radius R = 310 ± 70R . To fit the full spectrum, two additional components are required: a blue excess that can be fitted either by a hot blackbody (T 20, 000 K) or a power law (spectral index α ≈ 4) and is likely due to X-ray emission reprocessed in the outer accretion disk or the donor star; and a red excess that is well fitted by a blackbody with a temperature of ∼ 1100 K, and is likely due to warm dust in the vicinity of SN2010da. The presence of a red supergiant in this system implies an orbital period of at least 0.8-2.1 years, assuming Roche lobe overflow. Given the large donor-tocompact object mass ratio, orbital modulations of the radial velocity of the red supergiant are likely undetectable. However, the radial velocity amplitude of the neutron star is large enough (up to 40-60 km s −1 ) to potentially be measured in the future, unless the system is viewed at a very unfavorable inclination.

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Red Supergiants as Cosmic Abundance Probes: The Sculptor Galaxy NGC 300

Cited by 58 publications

References 49 publications

NGC 55: a disc galaxy with flat abundance gradients

NGC 55: a disc galaxy with flat abundance gradients

Asymmetric spatial distribution of subsolar metallicity stars in the Milky Way nuclear star cluster

Discovery of a Red Supergiant Donor Star in SN2010da/NGC 300 ULX-1

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