A Census of Star Formation in the Outer Galaxy. II. The GLIMPSE360 Field

Winston, E.; Hora, J. L.; Tolls, Volker

doi:10.3847/1538-3881/ab99c8

Cited by 18 publications

(52 citation statements)

References 79 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We classify objects obtained from the GLIMPSE I, II, 3D, Vela-Carina (Majewski et al 2007;Zasowski et al 2009), Cygnus X (Beerer et al 2010), andSMOG (Winston et al 2019) IRAC catalogs, using ancillary data from the near-IR 2MASS (Skrutskie et al 2006), UKIDSS (Lawrence et al 2007), and VVV (Minniti et al 2010) surveys, in the most comprehensive search for YSOs in the inner Galactic midplane to date. This catalog is largely restricted to the inner Galaxy, and thus is complementary to YSO searches in the outer Galaxy (e.g., Winston et al 2020).…”

Section: Discussionmentioning

confidence: 99%

“…In our study, we relax these criteria to identify significantly more YSOs candidates, but use patterns in the IRAC photometry to better distinguish between YSOs and contaminants. Our survey area also overlaps YSO catalogs for Cygnus X (Beerer et al 2010;Winston et al 2020) and the Spitzer Mapping of the Outer Galaxy (SMOG; Winston et al 2019) survey; we use the latter as a benchmark to compare to our results.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Kuhn

Krone-Martins

Castro-Ginard

et al. 2021

ApJS

View full text Add to dashboard Cite

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

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Kuhn

Krone-Martins

Castro-Ginard

et al. 2021

ApJS

View full text Add to dashboard Cite

show abstract

“…We identified the YSO candidates in our compiled catalog by selecting objects with excess IR emission, a result of the reprocessed stellar radiation from the cool, dusty material in the surrounding circumstellar disks and envelopes. After removing background sources, we selected the YSO candidates using various color-color cuts to distinguish them from cool or reddened stars (Allen et al 2004;Gutermuth et al 2004;Winston et al 2007Winston et al , 2020. Hereafter we will refer to the YSO candidates as "YSOs," but a definitive classification would require a more detailed analysis of the spectra and other characteristics of each object.…”

Section: Yso Identification and Classificationmentioning

confidence: 99%

“…We refer to all such sources as background sources (acknowledging that some stars and PAH emission may actually be foreground contamination) and removed them before proceeding with the YSO selection. We follow the selection criteria described in Winston et al (2020), which is adapted from Winston et al (2019); Gutermuth et al (2008Gutermuth et al ( , 2009 and reported in Appendix B.…”

Section: Background Sourcesmentioning

confidence: 99%

Testing Models of Triggered Star Formation with Young Stellar Objects in Cepheus OB4

Mintz,

Hora,

Winston

2021

Preprint

Self Cite

View full text Add to dashboard Cite

OB associations are home to newly formed massive stars, whose turbulent winds and ionizing flux create H II regions rich with star formation. Studying the distribution and abundance of young stellar objects (YSOs) in these ionized bubbles can provide essential insight into the physical processes that shape their formation, allowing us to test competing models of star formation. In this work, we examined one such OB association, Cepheus OB4 (Cep OB4) -a well-suited region for studying YSOs due to its Galactic location, proximity, and geometry. We created a photometric catalog from Spitzer /IRAC mosaics in bands 1 (3.6 µm) and 2 (4.5 µm). We supplemented the catalog with photometry from WISE, 2MASS, IRAC bands 3 (5.8 µm) and 4 (8.0 µm), MIPS 24 µm, and MMIRS near IR data. We used color-color selections to identify 821 YSOs, which we classified using the IR slope of the YSOs' spectral energy distributions (SEDs), finding 67 Class I, 103 flat spectrum, 569 Class II, and 82 Class III YSOs. We conducted a clustering analysis of the Cep OB4 YSOs and fit their SEDs. We found many young Class I objects distributed in the surrounding shell and pillars as well as a relative age gradient of unclustered sources, with YSOs generally decreasing in age with distance from the central cluster. Both of these results indicate that the expansion of the H II region may have triggered star formation in Cep OB4.

show abstract

“…In the Galaxy, observations suggest that the majority (Γ = 0.5 to 1.0) of star formation occurs in embedded clusters (e.g. Carpenter et al 1995;Carpenter 2000;Lada & Lada 2003;Porras et al 2003;Bressert et al 2010;Winston et al 2020). An independent piece of evidence for Γ close to 1 comes from the observed lower binary fraction of field stars in contrast to the binary fraction in star forming regions, which can be explained as a result of dynamical processing within clusters (Kroupa 1995a,b;Marks & Kroupa 2011).…”

Section: Introductionmentioning

confidence: 99%

Do the majority of stars form as gravitationally unbound?

Dinnbier,

Kroupa,

Anderson

2022

Preprint

View full text Add to dashboard Cite

Context. Some of the youngest stars (age 10 Myr) are clustered, while many others are observed scattered throughout star forming regions or in complete isolation. It has been intensively debated whether the scattered or isolated stars originate in star clusters, or if they form truly isolated, which could help constrain the possibilities how massive stars are formed. Aims. We adopt the assumption that all stars form in gravitationally bound star clusters embedded in molecular cloud cores (Γ-1 model), which expel their natal gas early after their formation, and compare the fraction of stars found in clusters with observational data. Methods. The star clusters are modelled by the code nbody6, which includes binary stars, stellar and circumbinary evolution, gas expulsion, and the external gravitational field of their host galaxy. Results. We find that small changes in the assumptions in the current theoretical model estimating the fraction, Γ, of stars forming in embedded clusters have a large influence on the results, and we present a counterexample as an illustration. This calls into question theoretical arguments about Γ in embedded clusters, and it suggests that there is no firm theoretical ground for low Γ in galaxies with lower star formation rates (SFRs). Instead, the assumption that all stars form in embedded clusters is in agreement with observational data for the youngest stars (age 10 Myr). In the Γ-1 scenario, the observed fraction of the youngest stars in clusters increases with the SFR only weakly; the increase is caused by the presence of more massive clusters in galaxies with higher SFRs, which release fewer stars to the field in proportion to their mass. The Γ-1 model yields a higher fraction of stars in clusters for older stars (age between 10 Myr and 300 Myr) than what is observed. This discrepancy can be caused by initially less compact clusters and/or a slightly lower star formation efficiency than originally assumed in the Γ-1 model, or by interactions of the post gas expulsion revirialised open clusters with molecular clouds.

show abstract

A Census of Star Formation in the Outer Galaxy. II. The GLIMPSE360 Field

Cited by 18 publications

References 79 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

Testing Models of Triggered Star Formation with Young Stellar Objects in Cepheus OB4

Do the majority of stars form as gravitationally unbound?

Contact Info

Product

Resources

About