Infrared Properties of Asymptotic Giant Branch Stars in Our Galaxy and the Magellanic Clouds

Suh, Kwang Wook

doi:10.3847/1538-4357/ab6609

Cited by 12 publications

(6 citation statements)

References 72 publications

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“…Certain evolved stars, including dusty red giants, AGB stars, post-AGB stars, and red super giants (RSGs), have red IR SEDs due to dusty stellar winds (e.g., Marengo et al 1997Marengo et al , 1999Groenewegen 2012;Chun et al 2015;Suh 2020), making such objects a significant category of contaminant in infrared YSO catalogs (e.g., Robitaille et al 2008;Povich et al 2013). Reiter et al (2015) present a sample of AGB stars (including O-rich, S-rich, and C-rich stars) and RSG stars with JHK and IRAC photometry.…”

Section: B1 Evolved Starsmentioning

confidence: 99%

SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane

Kuhn

Krone-Martins

Castro-Ginard

et al. 2021

ApJS

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We present ∼120,000 Spitzer/IRAC candidate young stellar objects (YSOs) based on surveys of the Galactic midplane between ℓ ∼ 255°and 110°, including the GLIMPSE I, II, and 3D, Vela-Carina, Cygnus X, and SMOG surveys (613 square degrees), augmented by near-infrared catalogs. We employed a classification scheme that uses the flexibility of a tailored statistical learning method and curated YSO data sets to take full advantage of Spitzer's spatial resolution and sensitivity in the mid-infrared ∼3-9 μm range. Multiwavelength color/magnitude distributions provide intuition about how the classifier separates YSOs from other red IRAC sources and validate that the sample is consistent with expectations for disk/envelope-bearing pre-main-sequence stars. We also identify areas of IRAC color space associated with objects with strong silicate absorption or polycyclic aromatic hydrocarbon emission. Spatial distributions and variability properties help corroborate the youthful nature of our sample. Most of the candidates are in regions with mid-IR nebulosity, associated with star-forming clouds, but others appear distributed in the field. Using Gaia DR2 distance estimates, we find groups of YSO candidates associated with the Local Arm, the Sagittarius-Carina Arm, and the Scutum-Centaurus Arm. Candidate YSOs visible to the Zwicky Transient Facility tend to exhibit higher variability amplitudes than randomly selected field stars of the same magnitude, with many high-amplitude variables having light-curve morphologies characteristic of YSOs. Given that no current or planned instruments will significantly exceed IRAC's spatial resolution while possessing its wide-area mapping capabilities, Spitzer-based catalogs such as ours will remain the main resources for mid-infrared YSOs in the Galactic midplane for the near future. Unified AstronomyThesaurus concepts: Young stellar objects (1834); Milky Way disk (1050); Star formation (1569); Star forming regions (1565); Stellar associations (1582) Supporting material: data behind figure, figure sets, FITS files

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Section: B1 Evolved Starsmentioning

confidence: 99%

SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane

Kuhn

Krone-Martins

Castro-Ginard

et al. 2021

ApJS

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“…In the mid-infrared, where SPICY selection was performed, the objects whose colors are most easily confused with YSOs are highly reddened background evolved stars (Povich et al 2011(Povich et al , 2013, including asymptotic-giant-branch (AGB) stars and post-AGB stars (Robitaille et al 2008;Suh 2020), dusty red-giant-branch (RGB) stars (Groenewegen 2012), post-RGB stars produced by binary interaction (Kamath et al 2016), and compact planetary nebulae (PNe; Rebull et al 2010). Classical Be stars with small infrared excesses from circumstellar freefree emission (Rebull et al 2010;Rivinius et al 2013), symbiotic stars (Waters & Waelkens 1998), and cataclysmic variables (CVs) with infrared excess (Dubus et al 2004;Akras et al 2019) are other possible contaminants.…”

Section: Classification As Pre-main-sequence Starsmentioning

confidence: 99%

Spectroscopic Confirmation of a Population of Isolated, Intermediate-mass Young Stellar Objects

Kuhn

Ramzi

Povich

et al. 2022

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Wide-field searches for young stellar objects (YSOs) can place useful constraints on the prevalence of clustered versus distributed star formation. The Spitzer/IRAC Candidate YSO (SPICY) catalog is one of the largest compilations of such objects (∼120,000 candidates in the Galactic midplane). Many SPICY candidates are spatially clustered, but, perhaps surprisingly, approximately half the candidates appear spatially distributed. To better characterize this unexpected population and confirm its nature, we obtained Palomar/DBSP spectroscopy for 26 of the optically bright (G < 15 mag) “isolated” YSO candidates. We confirm the YSO classifications of all 26 sources based on their positions on the Hertzsprung–Russell diagram, H and Ca ii line emission from over half the sample, and robust detection of infrared excesses. This implies a contamination rate of <10% for SPICY stars that meet our optical selection criteria. Spectral types range from B4 to K3, with A-type stars being the most common. Spectral energy distributions, diffuse interstellar bands, and Galactic extinction maps indicate moderate-to-high extinction. Stellar masses range from ∼1 to 7 M ⊙, and the estimated accretion rates, ranging from 3 × 10−8 to 3 × 10−7 M ⊙ yr−1, are typical for YSOs in this mass range. The 3D spatial distribution of these stars, based on Gaia astrometry, reveals that the “isolated” YSOs are not evenly distributed in the Solar neighborhood but are concentrated in kiloparsec-scale dusty Galactic structures that also contain the majority of the SPICY YSO clusters. Thus, the processes that produce large Galactic star-forming structures may yield nearly as many distributed as clustered YSOs.

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“…Such period-colour relations are well known for pulsating AGB stars in the Galaxy (Engels et al 1983;Whitelock et al 1994). A recent update using WISE colours including several thousand AGB stars in the Galaxy, as well as in the Large Magellanic Cloud, has been presented by Suh (2020). The relation is also found by the Gaia Collaboration et al (2019) in long-period variables within 1 kpc distance from the Sun using Gaia colours.…”

Section: Period-colour Correlationsmentioning

confidence: 58%

An infrared study of Galactic OH/IR stars. III. Variability properties of the Arecibo sample

Jiménez-Esteban,

Engels,

Aguado

et al. 2021

Preprint

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We present the results of a near-infrared (NIR) monitoring program carried out between 1999 and 2005 to determine the variability properties of the 'Arecibo sample of OH/IR stars'. The sample consists of 385 IRAS-selected Asymptotic Giant Branch (AGB) candidates, for which their O-rich chemistry has been proven by the detection of 1612 MHz OH maser emission. The monitoring data was complemented by data collected from public optical and NIR surveys. We fitted the light curves obtained in the optical and NIR bands with a model using an asymmetric cosine function, and derived a period for 345 sources (∼ 90% of the sample). Based on their variability properties, most of the Arecibo sources are classified as long-period large-amplitude variable stars (LPLAV), 4% as (candidate) post-AGB stars, and 3% remain unclassified although they are likely post-AGB stars or highly obscured AGB stars. The period distribution of the LPLAVs peaks at ∼ 400 days, with periods between 300 and 800 days for most of the sources, and has a long tail up to ∼ 2100 days. Typically, the amplitudes are between 1 and 3 mag in the NIR and between 2 and 6 mag in the optical. We find correlations between periods and amplitudes, with larger amplitudes associated to longer periods, as well as between the period and the infrared colours, with the longer periods linked to the redder sources. Among the post-AGB stars, the light curve of IRAS 19566+3423 was exceptional, showing a large systematic increase (> 0.4 mag yr −1 ) in K-band brightness over 7 years.

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Infrared Properties of Asymptotic Giant Branch Stars in Our Galaxy and the Magellanic Clouds

Cited by 12 publications

References 72 publications

SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane

SPICY: The Spitzer/IRAC Candidate YSO Catalog for the Inner Galactic Midplane

Spectroscopic Confirmation of a Population of Isolated, Intermediate-mass Young Stellar Objects

An infrared study of Galactic OH/IR stars. III. Variability properties of the Arecibo sample

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