A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies

Deidre A. Hunter; Angela Adamo; Bruce G. Elmegreen; Samavarti Gallardo; Janice C. Lee; David O. Cook; David Thilker; Bridget Kayitesi; Hwihyun Kim; Lauren Kahre; Leonardo Ubeda; Stacey N. Bright; Jenna E. Ryon; Daniela Calzetti; Monica Tosi; Kathryn Grasha; Matteo Messa; Michele Fumagalli; Daniel A. Dale; Elena Sabbi; Michele Cignoni; Linda J. Smith; Dimitrios M. Gouliermis; Eva K. Grebel; Alessandra Aloisi; Bradley C. Whitmore; Rupali Chandar; Kelsey E. Johnson

doi:10.3847/1538-3881/aac50e

A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies

Deidre A. Hunter, Angela Adamo, Bruce G. Elmegreen, Samavarti Gallardo, Janice C. Lee, David O. Cook, David Thilker, Bridget Kayitesi, Hwihyun Kim, Lauren Kahre, Leonardo Ubeda, Stacey N. Bright, Jenna E. Ryon, Daniela Calzetti, Monica Tosi, Kathryn Grasha, Matteo Messa, Michele Fumagalli, Daniel A. Dale, Elena SabbiMichele Cignoni, Linda J. Smith, Dimitrios M. Gouliermis, Eva K. Grebel, Alessandra Aloisi, Bradley C. Whitmore, Rupali Chandar, Kelsey E. Johnson

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Abstract

We have explored the role environmental factors play in determining characteristics of young stellar objects in nearby dwarf irregular and blue compact dwarf galaxies. Star clusters are characterized by concentrations, masses, and formation rates; OB associations by mass and mass surface density; O stars by their numbers and near-ultraviolet absolute magnitudes; and H ii regions by Hα surface brightnesses. These characteristics are compared to surrounding galactic pressure, stellar mass density, H i surface density, and star formation rate (SFR) surface density. We find no trend of cluster characteristics with environmental properties, implying that larger-scale effects are more important in determining cluster characteristics or that rapid dynamical evolution erases any memory of the initial conditions. On the other hand, the most massive OB associations are found at higher pressure and H i surface density, and there is a trend of higher H ii region Hα surface brightness with higher pressure, suggesting that a higher concentration of massive stars and gas is found preferentially in regions of higher pressure. At low pressures we find massive stars but not bound clusters and OB associations. We do not find evidence for an increase of cluster formation efficiency as a function of SFR density. However, there is an increase in the ratio of the number of clusters to the number of O stars with increasing pressure, perhaps reflecting an increase in clustering properties with SFR.

Original language	English
Article number	21
Journal	Astronomical Journal
Volume	156
Issue number	1
DOIs	https://doi.org/10.3847/1538-3881/aac50e
Publication status	Published - Jul 2018
Externally published	Yes

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Hunter, D. A., Adamo, A., Elmegreen, B. G., Gallardo, S., Lee, J. C., Cook, D. O., Thilker, D., Kayitesi, B., Kim, H., Kahre, L., Ubeda, L., Bright, S. N., Ryon, J. E., Calzetti, D., Tosi, M., Grasha, K., Messa, M., Fumagalli, M., Dale, D. A., ... Johnson, K. E. (2018). A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies. Astronomical Journal, 156(1), Article 21. https://doi.org/10.3847/1538-3881/aac50e

@article{ab25ec6b025a4e7b9b25b74e7a30475b,

title = "A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies",

abstract = "We have explored the role environmental factors play in determining characteristics of young stellar objects in nearby dwarf irregular and blue compact dwarf galaxies. Star clusters are characterized by concentrations, masses, and formation rates; OB associations by mass and mass surface density; O stars by their numbers and near-ultraviolet absolute magnitudes; and H ii regions by Hα surface brightnesses. These characteristics are compared to surrounding galactic pressure, stellar mass density, H i surface density, and star formation rate (SFR) surface density. We find no trend of cluster characteristics with environmental properties, implying that larger-scale effects are more important in determining cluster characteristics or that rapid dynamical evolution erases any memory of the initial conditions. On the other hand, the most massive OB associations are found at higher pressure and H i surface density, and there is a trend of higher H ii region Hα surface brightness with higher pressure, suggesting that a higher concentration of massive stars and gas is found preferentially in regions of higher pressure. At low pressures we find massive stars but not bound clusters and OB associations. We do not find evidence for an increase of cluster formation efficiency as a function of SFR density. However, there is an increase in the ratio of the number of clusters to the number of O stars with increasing pressure, perhaps reflecting an increase in clustering properties with SFR.",

keywords = "galaxies: dwarf, galaxies: individual (DDO 50, DDO 53, DDO 63, NGC 3738, Haro 29)",

author = "Hunter, {Deidre A.} and Angela Adamo and Elmegreen, {Bruce G.} and Samavarti Gallardo and Lee, {Janice C.} and Cook, {David O.} and David Thilker and Bridget Kayitesi and Hwihyun Kim and Lauren Kahre and Leonardo Ubeda and Bright, {Stacey N.} and Ryon, {Jenna E.} and Daniela Calzetti and Monica Tosi and Kathryn Grasha and Matteo Messa and Michele Fumagalli and Dale, {Daniel A.} and Elena Sabbi and Michele Cignoni and Smith, {Linda J.} and Gouliermis, {Dimitrios M.} and Grebel, {Eva K.} and Alessandra Aloisi and Whitmore, {Bradley C.} and Rupali Chandar and Johnson, {Kelsey E.}",

year = "2018",

month = jul,

doi = "10.3847/1538-3881/aac50e",

language = "English",

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Hunter, DA, Adamo, A, Elmegreen, BG, Gallardo, S, Lee, JC, Cook, DO, Thilker, D, Kayitesi, B, Kim, H, Kahre, L, Ubeda, L, Bright, SN, Ryon, JE, Calzetti, D, Tosi, M, Grasha, K, Messa, M, Fumagalli, M, Dale, DA, Sabbi, E, Cignoni, M, Smith, LJ, Gouliermis, DM, Grebel, EK, Aloisi, A, Whitmore, BC, Chandar, R & Johnson, KE 2018, 'A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies', Astronomical Journal, vol. 156, no. 1, 21. https://doi.org/10.3847/1538-3881/aac50e

TY - JOUR

T1 - A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies

AU - Hunter, Deidre A.

AU - Adamo, Angela

AU - Elmegreen, Bruce G.

AU - Gallardo, Samavarti

AU - Lee, Janice C.

AU - Cook, David O.

AU - Thilker, David

AU - Kayitesi, Bridget

AU - Kim, Hwihyun

AU - Kahre, Lauren

AU - Ubeda, Leonardo

AU - Bright, Stacey N.

AU - Ryon, Jenna E.

AU - Calzetti, Daniela

AU - Tosi, Monica

AU - Grasha, Kathryn

AU - Messa, Matteo

AU - Fumagalli, Michele

AU - Dale, Daniel A.

AU - Sabbi, Elena

AU - Cignoni, Michele

AU - Smith, Linda J.

AU - Gouliermis, Dimitrios M.

AU - Grebel, Eva K.

AU - Aloisi, Alessandra

AU - Whitmore, Bradley C.

AU - Chandar, Rupali

AU - Johnson, Kelsey E.

PY - 2018/7

Y1 - 2018/7

N2 - We have explored the role environmental factors play in determining characteristics of young stellar objects in nearby dwarf irregular and blue compact dwarf galaxies. Star clusters are characterized by concentrations, masses, and formation rates; OB associations by mass and mass surface density; O stars by their numbers and near-ultraviolet absolute magnitudes; and H ii regions by Hα surface brightnesses. These characteristics are compared to surrounding galactic pressure, stellar mass density, H i surface density, and star formation rate (SFR) surface density. We find no trend of cluster characteristics with environmental properties, implying that larger-scale effects are more important in determining cluster characteristics or that rapid dynamical evolution erases any memory of the initial conditions. On the other hand, the most massive OB associations are found at higher pressure and H i surface density, and there is a trend of higher H ii region Hα surface brightness with higher pressure, suggesting that a higher concentration of massive stars and gas is found preferentially in regions of higher pressure. At low pressures we find massive stars but not bound clusters and OB associations. We do not find evidence for an increase of cluster formation efficiency as a function of SFR density. However, there is an increase in the ratio of the number of clusters to the number of O stars with increasing pressure, perhaps reflecting an increase in clustering properties with SFR.

AB - We have explored the role environmental factors play in determining characteristics of young stellar objects in nearby dwarf irregular and blue compact dwarf galaxies. Star clusters are characterized by concentrations, masses, and formation rates; OB associations by mass and mass surface density; O stars by their numbers and near-ultraviolet absolute magnitudes; and H ii regions by Hα surface brightnesses. These characteristics are compared to surrounding galactic pressure, stellar mass density, H i surface density, and star formation rate (SFR) surface density. We find no trend of cluster characteristics with environmental properties, implying that larger-scale effects are more important in determining cluster characteristics or that rapid dynamical evolution erases any memory of the initial conditions. On the other hand, the most massive OB associations are found at higher pressure and H i surface density, and there is a trend of higher H ii region Hα surface brightness with higher pressure, suggesting that a higher concentration of massive stars and gas is found preferentially in regions of higher pressure. At low pressures we find massive stars but not bound clusters and OB associations. We do not find evidence for an increase of cluster formation efficiency as a function of SFR density. However, there is an increase in the ratio of the number of clusters to the number of O stars with increasing pressure, perhaps reflecting an increase in clustering properties with SFR.

KW - galaxies: dwarf

KW - galaxies: individual (DDO 50, DDO 53, DDO 63, NGC 3738, Haro 29)

UR - http://www.scopus.com/inward/record.url?scp=85049919340&partnerID=8YFLogxK

U2 - 10.3847/1538-3881/aac50e

DO - 10.3847/1538-3881/aac50e

M3 - Article

SN - 0004-6256

VL - 156

JO - Astronomical Journal

JF - Astronomical Journal

IS - 1

M1 - 21

ER -

A Comparison of Young Star Properties with Local Galactic Environment for LEGUS/LITTLE THINGS Dwarf Irregular Galaxies

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