On the origin of nitrogen at low metallicity

Roy, A.B.; Dopita, Michael A.; Krumholz, Mark R.; Kewley, Lisa J.; Sutherland, Ralph S.; Heger, Alexander

doi:10.1093/mnras/stab376

Cited by 21 publications

(31 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The mass loss of a massive star is dependent on its mass, metallicity and rotation rate. The higher the rotation rate, the larger the mass loss [4,5,69]. With mass loss, the angular momentum transported from the core to the surface eventually gets lost to the interstellar medium.…”

Section: Single Stars Versus Binary Stars As Lgrb Progenitorsmentioning

confidence: 99%

“…In rotating stars, chemical mixing due to several rotational instabilities (see Section 5 for details) dredges up the elements from the inner convective core to the surface, crossing the radiative barrier. Therefore, a rapidly rotating massive star can be quasi-chemically homogeneously mixed [4][5][6]57,70] without a clear chemical boundary between the inner convective core and the radiative envelope. The chemically homogeneous evolution (CHE) supplies hydrogen to the core for a longer time producing a larger He-rich core compared to the non-rotating star, leaving little or no hydrogen [57,71].…”

Section: Single Stars Versus Binary Stars As Lgrb Progenitorsmentioning

confidence: 99%

“…Table 1. Taken from [5]. Criteria to classify stars as O, WNL, WNE, WC, and WO based on the surface enhancement of various elements and core burning status.…”

Section: Rotation Ratementioning

confidence: 99%

“…Surface state and core state refer to conditions at the stellar surface and the centre of the star, respectively; X Q is the mass fraction of element Q. See [5] for detail.…”

Section: Rotation Ratementioning

confidence: 99%

“…Massive stars ( 10 M ) enter the Wolf-Rayet (WR) phase towards the end of or after the main-sequence [4]. Depending on the spectroscopic identification of heavy elements, such as helium, nitrogen, carbon, oxygen [4,5], and their excitation states, WR stars are primarily classified in three categories: WN, WC, and WO (see Table 4 of [5]). Theoretically, WN and WC stars are believed to be progenitors of Type Ib and Ic core-collapse supernovae (SNe), respectively, given their pre-SN He-/ CO-core masses and the absence of surface H and H/He [6].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Progenitors of Long-Duration Gamma-ray Bursts

Roy

2021

Galaxies

Self Cite

View full text Add to dashboard Cite

We review the current scenario of long-duration Gamma-ray burst (LGRB) progenitors, and in addition, present models of massive stars for a mass range of 10-150M⊙ with ΔM=10M⊙ and rotation rate v/vcrit=0 to 0.6 with a velocity resolution Δv/vcrit=0.1. We further discuss possible metallicity and rotation rate distribution from our models that might be preferable for the creation of successful LGRB candidates given the observed LGRB rates and their metallicity evolution. In the current understanding, LGRBs are associated with Type-Ic supernovae (SNe). To establish LGRB-SN correlation, we discuss three observational paths: (i) space-time coincidence, (ii) evidence from photometric light curves of LGRB afterglows and SN Type-Ic, (iii) spectroscopic study of both LGRB afterglow and SN. Superluminous SNe are also believed to have the same origin as LGRBs. Therefore, we discuss constraints on the progenitor parameters that can possibly dissociate these two events from a theoretical perspective. We further discuss the scenario of single star versus binary star as a more probable pathway to create LGRBs. Given the limited parameter space in the mass, mass ratio and separation between the two components in a binary, binary channel is less likely to create LGRBs to match the observed LGRB rate. Despite effectively-single massive stars are fewer in number compared to interacting binaries, their chemically homogeneous evolution (CHE) might be the major channel for LGRB production.

show abstract

Section: Single Stars Versus Binary Stars As Lgrb Progenitorsmentioning

confidence: 99%

Section: Single Stars Versus Binary Stars As Lgrb Progenitorsmentioning

confidence: 99%

“…Table 1. Taken from [5]. Criteria to classify stars as O, WNL, WNE, WC, and WO based on the surface enhancement of various elements and core burning status.…”

Section: Rotation Ratementioning

confidence: 99%

“…Surface state and core state refer to conditions at the stellar surface and the centre of the star, respectively; X Q is the mass fraction of element Q. See [5] for detail.…”

Section: Rotation Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Progenitors of Long-Duration Gamma-ray Bursts

Roy

2021

Galaxies

Self Cite

View full text Add to dashboard Cite

show abstract

Can pre-supernova winds from massive stars enrich the interstellar medium with nitrogen at high redshift?

Roy¹,

Krumholz

Dopita

et al. 2020

Proc. IAU

View full text Add to dashboard Cite

Understanding the nucleosynthetic origin of nitrogen and the evolution of the N/O ratio in the interstellar medium is crucial for a comprehensive picture of galaxy chemical evolution at high-redshift because most observational metallicity (O/H) estimates are implicitly dependent on the N/O ratio. The observed N/O at high-redshift shows an overall constancy with O/H, albeit with a large scatter. We show that these heretofore unexplained features can be explained by the pre-supernova wind yields from rotating massive stars (M≳10M⊙,ν/νcrit≳0.4). Our models naturally produce the observed N/O plateau, as well as the scatter at low O/H. We find the scatter to arise from varying star formation efficiency. However, the models that have supernovae dominated yields produce a poor fit to the observed N/O at low O/H. This peculiar abundance pattern at low O/H suggests that dwarf galaxies are most likely to be devoid of SNe yields and are primarily enriched by pre-supernova wind abundances.

show abstract

Chemical Evolution of R-process Elements in Stars (CERES)

Fernandes de Melo,

Lombardo,

Alencastro Puls

et al. 2024

A&A

View full text Add to dashboard Cite

Carbon, nitrogen, and oxygen are the most abundant elements throughout the universe, after hydrogen and helium. Studying these elements in low-metallicity stars can provide crucial information on the chemical composition in the early Galaxy and possible internal mixing processes that can alter the surface composition of the stars. This work aims to investigate the chemical abundance patterns for CNO elements and Li in a homogeneously analyzed sample of 52 metal-poor halo giant stars. From these results, we have been able to determine whether internal mixing processes have taken place in these stars. We used high-resolution spectra with a high signal-to-noise ratio (S/N) to carry out a spectral synthesis to derive detailed C, N, O, and Li abundances for a sample of stars with metallicities in the range of$-$3.58 leq Fe/H leq $-$1.79\,dex. Our study was based on the assumption of one-dimensional (1D) local thermodynamic equilibrium (LTE) atmospheres. Based on carbon and nitrogen abundances, we investigated the deep mixing taking place within stars along the red giant branch (RGB). The individual abundances of carbon decrease towards the upper RGB while nitrogen shows an increasing trend, indicating that carbon has been converted into nitrogen. No signatures of ON-cycle processed material were found for the stars in our sample. We computed a set of galactic chemical evolution (GCE) models, implementing different sets of massive star yields, both with and without including the effects of stellar rotation on nucleosynthesis. We confirm that stellar rotation is necessary to explain the highest N/Fe and N/O ratios observed in unmixed halo stars. The predicted level of N enhancement varies sensibly in dependence of the specific set of yields that are adopted. For stars with stellar parameters similar to those of our sample, heavy elements such as Sr, Y, and Zr appear to have unchanged abundances despite the stellar evolution mixing processes. The unmixed RGB stars provide very useful constraints on chemical evolution models of the Galaxy. As they are more luminous than unevolved (main sequence and turnoff) stars, they also allow for stars to be probed at greater distances. The stellar CN-cycle clearly changes the atmospheric abundances of the lighter elements, but no changes were detected with respect to the heavy elements.

show abstract

On the origin of nitrogen at low metallicity

Cited by 21 publications

References 53 publications

Progenitors of Long-Duration Gamma-ray Bursts

Progenitors of Long-Duration Gamma-ray Bursts

Can pre-supernova winds from massive stars enrich the interstellar medium with nitrogen at high redshift?

Chemical Evolution of R-process Elements in Stars (CERES)

Contact Info

Product

Resources

About