The Sample of Red Supergiants in 12 Low-mass Galaxies of the Local Group

Ren, Yi; Jiang, Biwei; Yang, Ming; Wang, Tianding; Ren, Tongtian

doi:10.3847/1538-4357/ac307b

“…RSG stars are massive stars with masses ranging from ∼ 8 to 30 M ⊙ . Typically, RSG stars have high luminosities of ∼ 4000 − 400000 L ⊙ , low effective temperatures of ∼ 3300 − 5000 K, and radii up to 1500 R ⊙ (Levesque et al 2005;Massey et al 2007;Wittkowski et al 2012;Davies et al 2013;Yang et al 2018Yang et al , 2021Ren et al 2021). They are the descendants of H-burning O-and B-type massive stars and thought to evolve horizontally on the Hertzsprung-Russell (H-R) diagram.…”

Section: Introductionmentioning

confidence: 99%

The Optical to Infrared Extinction Law of Magellanic Clouds Based on Red Supergiant and Classical Cepheid

Wang¹,

Chen²

2023

Preprint

2

3

0

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Precise interstellar dust extinction laws are important to infer the intrinsic properties of reddened objects and correctly interpret observations. In this work, we attempt to measure the optical-infrared extinction laws of the Large and Small Magellanic Clouds (LMC and SMC) by using red supergiant (RSG) stars and classical Cepheids as extinction tracers. The spectroscopic RSG samples are constructed based on the APOGEE spectral parameters, Gaia astrometric data, and multi-band photometry. We establish the effective temperature-intrinsic color relations for RSG stars and determine the color excess ratio (CER) E(λ − G RP )/E(G BP − G RP ) for LMC and SMC. We use classical Cepheids to derive base relative extinction A GRP /E(G BP − G RP ). The results are 1.589 ± 0.014 and 1.412 ± 0.041 for LMC and SMC. By combining CERs with A GRP /E(G BP − G RP ), the optical-infrared extinction coefficients A λ /A GRP are determined for 16 bands. We adjust the parameters of R V -dependent extinction laws and obtain the average extinction laws of LMC and SMC as R V = 3.40 ± 0.07 and R V = 2.53 ± 0.10, which are consistent with Gordon et al. (2003). In the optical bands, the adjusted R V extinction curves agree with the observations with deviations less than 3%.

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“…In addition, Massey's sample consists of the brightest RSG stars, and most of them have more circumstellar dust, so we did not include Massey's sample in this work. Yang et al (2019Yang et al ( , 2021 and Ren et al (2021) also provided the LMC and SMC RSG catalogs. After integrating their catalogs and cross-matching them with APOGEE data, we obtained a combined catalog of 1846 (LMC) and 626 (SMC) RSG stars.…”

Section: The Spectroscopic Rsg Catalogmentioning

confidence: 99%

“…RSG stars are massive stars with masses ranging from ∼ 8 to 30 M e . Typically, RSG stars have high luminosities of ∼4000-40,0000 L e , low effective temperatures of ∼3300-5000 K, and radii up to 1500 R e (Levesque et al 2005;Massey et al 2007;Wittkowski et al 2012;Davies et al 2013;Yang et al 2018Yang et al , 2021Ren et al 2021). They are the descendants of H-burning O-and B-type massive stars and thought to evolve horizontally on the Hertzsprung-Russell (H-R) diagram.…”

Section: Introductionmentioning

confidence: 99%

The Optical to Infrared Extinction Law of Magellanic Clouds Based on Red Supergiants and Classical Cepheids

Wang

¹

,

Chen

²

2023

ApJ

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Precise interstellar dust extinction laws are important to infer the intrinsic properties of reddened objects and correctly interpret observations. In this work, we attempt to measure the optical–infrared extinction laws of the Large and Small Magellanic Clouds (LMC and SMC) by using red supergiant (RSG) stars and classical Cepheids as extinction tracers. The spectroscopic RSG samples are constructed based on the APOGEE spectral parameters, Gaia astrometric data, and multiband photometry. We establish the effective temperature–intrinsic color relations for RSG stars and determine the color excess ratio (CER) E(λ − G RP)/E(G BP − G RP) for the LMC and SMC. We use classical Cepheids to derive base relative extinction A G RP / E ( G BP − G RP ) . The results are 1.589 ± 0.014 and 1.412 ± 0.041 for the LMC and SMC. By combining CERs with A G RP / E ( G BP − G RP ) , the optical–infrared extinction coefficients A λ / A G RP are determined for 16 bands. We adjust the parameters of R V -dependent extinction laws and obtain average extinction laws for the LMC and SMC of R V = 3.40 ± 0.07 and R V = 2.53 ± 0.10, respectively, which are consistent with Gordon et al. In the optical bands, the adjusted R V extinction curves agree with the observations with deviations less than 3%.

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“…We adopt A 0.646 V 0 = mag and A 0.104 V 0 = mag to remove the foreground extinction for NGC 6822 and WLM (Schlafly & Finkbeiner 2011), respectively. The process for constructing the model SEDs for the tracers is the same as mentioned in Section 3.1, but we adopt Z/Z 0 = 1/10 for both NGC 6822 and WLM (Leaman 2012;Ren et al 2021aRen et al , 2021b. After result selection with the criteria mentioned in Section 3.3, 9 six tracers in NGC 6822 and four tracers in WLM with reliable results are selected for further analysis.…”

Section: Application In Other Nearby Star-resolved Galaxiesmentioning

confidence: 99%

Dust Extinction Law in Nearby Star-resolved Galaxies. II. M33 Traced by Supergiants

Wang¹,

Jian²,

Ren³

et al. 2022

ApJS

Self Cite

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The dust extinction curves toward individual sight lines in M33 are derived for the first time with a sample of reddened O-type and B-type supergiants obtained from the Local Group Galaxies Survey (LGGS). The observed photometric data are obtained from the LGGS, PS1 Survey, UKIRT, PHATTER Survey, Galaxy Evolution Explorer, Swift/UVOT, and XMM-SUSS. We combine the intrinsic spectral energy distributions (SEDs) obtained from the ATLAS9 and Tlusty stellar model atmosphere extinguished by the model extinction curves from the silicate-graphite dust model to construct model SEDs. The extinction traces are distributed along the arms in M33, and the derived extinction curves cover a wide range of shapes (R V ≈ 2–6), indicating the complexity of the interstellar environment and the inhomogeneous distribution of interstellar dust in M33. The average extinction curve with R V ≈ 3.39 and dust size distribution dn / da ∼ a − 3.45 exp ( − a / 0.25 ) is similar to that of the Milky Way but with a weaker 2175 Å bump and a slightly steeper rise in the far-UV band. The extinction in the V band of M33 is up to 2 mag, with a median value of A V ≈ 0.43 mag. The multiband extinction values from the UV to IR bands are also predicted for M33, which will provide extinction corrections for future works. The method adopted in this work is also applied to other star-resolved galaxies (NGC 6822 and WLM), but only a few extinction curves can be derived because of the limited observations.

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The Sample of Red Supergiants in 12 Low-mass Galaxies of the Local Group

Cited by 17 publications

References 94 publications

The Optical to Infrared Extinction Law of Magellanic Clouds Based on Red Supergiant and Classical Cepheid

The Optical to Infrared Extinction Law of Magellanic Clouds Based on Red Supergiant and Classical Cepheid

The Optical to Infrared Extinction Law of Magellanic Clouds Based on Red Supergiants and Classical Cepheids

Dust Extinction Law in Nearby Star-resolved Galaxies. II. M33 Traced by Supergiants

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