Unveiling the nature of candidate high-mass young stellar objects in the Magellanic Clouds with near-IR spectroscopy

Reiter, Megan; Nayak, Omnarayani; Meixner, Margaret; Jones, O. C.

doi:10.1093/mnras/sty3275

Cited by 7 publications

(20 citation statements)

References 98 publications

(148 reference statements)

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“…We detect Ca ii IRT emission towards 50% of the confirmed MYSOs, which agrees with the Galactic star forming region M17 (66%; Ramírez-Tannus et al 2017). Our detection rate of Brγ is 80%, which is consistent with the high detection rate in other LMC samples (Ward et al 2016;Reiter et al 2019), SMC samples (Ward et al 2017;Reiter et al 2019), and larger Galactic samples (Cooper et al 2013;Pomohaci et al 2017). In Fig.…”

Section: Comparison To Other Samplessupporting

confidence: 89%

“…Nayak et al (2016) classified S9 (J84.703995-69.079110 in their work) as a Type I YSO and determined L = 6.81 × 10 4 L , and M = 23.9 M of S9 . More recently, Reiter et al (2019) computed L = 5.01 × 10 5 L , T eff = 21120 K, and A V = 2.46 mag, and see the CO bandheads in absorption (similar to S3-K in this work).…”

Section: S9supporting

confidence: 79%

“…S9 was also a Spitzer/IRS MYSO candidate, and was the most massive MYSO in the sample of Nayak et al (2016, although they may have mixed S9 with the massive young star VFTS 621 since they refer to S9 as the object with SpT O2). More remarkably is the absence of the CO bandhead absorption observed by Reiter et al (2019)…”

Section: Confirmation Of Mysosmentioning

confidence: 97%

“…The Very Large Telescope (VLT) allow us now to spectroscopically observe (apparent) single MYSOs in the Magellanic Clouds (e.g. Ward et al 2016Ward et al , 2017Rubio et al 2018;Reiter et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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VLT/X-shooter spectroscopy of massive young stellar objects in the 30 Doradus region of the Large Magellanic Cloud

Gelder

Kaper

Japelj

et al. 2020

A&A

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The process of massive star (M ≥ 8 M ) formation is still poorly understood. Observations of massive young stellar objects (MYSOs) are challenging due to their rarity, short formation timescale, large distances, and high circumstellar extinction. Here, we present the results of a spectroscopic analysis of a population of MYSOs in the Large Magellanic Cloud (LMC). We took advantage of the spectral resolution and wavelength coverage of X-shooter (300-2500 nm), mounted on the European Southern Observatory Very Large Telescope, to detect characteristic spectral features in a dozen MYSO candidates near 30 Doradus, the largest starburst region in the Local Group hosting the most massive stars known. The X-shooter spectra are strongly contaminated by nebular emission. We used a scaling method to subtract the nebular contamination from our objects. We detect Hα, β, [O i] 630.0 nm, Ca ii infrared triplet, [Fe ii] 1643.5 nm, fluorescent Fe ii 1687.8 nm, H 2 2121.8 nm, Brγ, and CO bandhead emission in the spectra of multiple candidates. This leads to the spectroscopic confirmation of 10 candidates as bona fide MYSOs. We compare our observations with photometric observations from the literature and find all MYSOs to have a strong near-infrared excess. We compute lower limits to the brightness and luminosity of the MYSO candidates, confirming the near-infrared excess and the massive nature of the objects. No clear correlation is seen between the Brγ luminosity and metallicity. Combining our sample with other LMC samples results in a combined detection rate of disk features such as fluorescent Fe ii and CO bandheads which is consistent with the Galactic rate (40%). Most of our MYSOs show outflow features.

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Section: Comparison To Other Samplessupporting

confidence: 89%

Section: S9supporting

confidence: 79%

Section: Confirmation Of Mysosmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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VLT/X-shooter spectroscopy of massive young stellar objects in the 30 Doradus region of the Large Magellanic Cloud

Gelder

Kaper

Japelj

et al. 2020

A&A

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“…Observations of Galactic and LMC SNRs show [Fe II] 1.644 µm : Paβ 1.25 µm ratios ranging from about 0.7 in young SNRs to ∼ 10 in older objects (Mouri et al 2000;Labrie & Pritchet 2006;Koo & Lee 2015). By contrast, this ratio is generally < 0.1 in H II regions and other photoionized nebulae (Lowe et al 1979;Armand et al 1996;Reiter et al 2019). An important advantage of [Fe II] 1.644 µm is that it is less sensitive to foreground absorption, which is important in the case of NGC 6946 since it lies only about 11.…”

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confidence: 99%

The Supernova Remnant Population of NGC6946 as Observed in [Fe II] 1.644 $μ$m with HST

Long,

Blair,

Winkler

et al. 2020

Preprint

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NGC 6946 is a high star formation rate face-on spiral galaxy that has hosted ten supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [S II]:Hα line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps between these two samples. Here, we apply [Fe II] 1.644 µm emission as a new diagnostic to search for supernova remnants in an attempt to resolve this discrepancy. [Fe II] is expected to be relatively strong in the radiative shocks of supernova remnants and almost absent in H II regions. It is less susceptible to the effects of absorption along the line of sight than the optical lines normally used to identify remnants. Using data from the WFC3 camera on HST, we identify 132 [Fe II] emission nebulae in NGC 6946 as likely supernova remnants. Of these, 54 align with previously known optical supernova remnants. The remaining 78 objects are new; of these 44 are visible in new HST imagery in Hα and [S II]. This brings the total number of supernova remnant candidates (from optical and/or IR data) in NGC 6946 to 225. A total of 14 coincidences with radio supernova remnant candidates (out of 30 in our search area) are found in this expanded list. The identification of so many new remnant candidates validates the use of [Fe II] imagery for finding remnants, and suggests that previous remnant searches in other galaxies may be far from complete.

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Near-infrared spectroscopy of embedded protostars in the massive metal-poor star-forming region NGC 346

Jones

Reiter

Sánchéz-Janssen

et al. 2022

Monthly Notices of the Royal Astronomical Society

Self Cite

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We present medium-resolution (R ∼ 4000) YJ, H & K band spectroscopy of candidate young stellar objects (YSOs) in NGC 346, the most active star-formation region in the metal-poor (Z = 1/5 Z⊙) Small Magellanic Cloud. The spectra were obtained with the KMOS (K-Band Multi Object Spectrograph) integral field instrument on the Very Large Telescope. From our initial sample of 18 candidate high-mass YSOs previously identified from mid-IR photometry and radiative transfer model fits to their spectral energy distributions, approximately half were resolved into multiple components by our integral-field data. In total we detect 30 continuum sources and extract reliable spectra for 12 of these objects. The spectra show various features including hydrogen recombination lines, and lines from H2, He i and [Fe ii], which are indicative of accretion, discs and outflowing material in massive YSOs. We spectroscopically confirm the youthful nature of nine YSO candidates, and identify two others as OB stars. All of the confirmed YSOs have Brγ in emission, but no emission is seen from the CO bandhead, despite other disc tracers present in the spectra. He i 1.083 μm emission is also detected at appreciably higher rates than for the Galaxy.

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Unveiling the nature of candidate high-mass young stellar objects in the Magellanic Clouds with near-IR spectroscopy

Cited by 7 publications

References 98 publications

VLT/X-shooter spectroscopy of massive young stellar objects in the 30 Doradus region of the Large Magellanic Cloud

VLT/X-shooter spectroscopy of massive young stellar objects in the 30 Doradus region of the Large Magellanic Cloud

The Supernova Remnant Population of NGC6946 as Observed in [Fe II] 1.644 $μ$m with HST

Near-infrared spectroscopy of embedded protostars in the massive metal-poor star-forming region NGC 346

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