Massive stars in the galaxies of the Local Group

Massey, Philip

doi:10.1016/j.newar.2013.05.002

Cited by 35 publications

(32 citation statements)

References 124 publications

(144 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The remote location combined with the metallicity gradient of M33 (Magrini et al 2007) also suggests that MCA-1B may provide intriguing clues to LBV behaviour at low metallicity. Throughout, we adopt a distance to M33 of 830 kpc, following Massey (2013). This is between estimates of 800 kpc (McConnachie et al 2009;Patel et al 2017) and 960 kpc (Bonanos et al 2006); adopting either of these these would only slightly alter the absolute magnitudes and implications for the initial mass of the star.…”

Section: Introductionmentioning

confidence: 99%

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

Smith

Andrews

Moe

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

MCA-1B (also called UIT003) is a luminous hot star in the western outskirts of M33, classified over 20 yr ago with a spectral type of Ofpe/WN9 and identified then as a candidate luminous blue variable (LBV). Palomar Transient Factory data reveal that this star brightened in 2010, with a light curve resembling that of the classic LBV star AF And in M31. Other Ofpe/WN9 stars have erupted as LBVs, but MCA-1B was unusual because it remained hot. It showed a WN-type spectrum throughout its eruption, whereas LBVs usually get much cooler. MCA-1B showed an almost four-fold increase in bolometric luminosity and a doubling of its radius, but its temperature stayed 29 kK. As it faded, it shifted to even hotter temperatures, exhibiting a WN7/WN8-type spectrum, and doubling its wind speed. MCA-1B is reminiscent of some supernova impostors, and its location resembles the isolated environment of SN 2009ip. It is most similar to HD 5980 (in the Small Magellanic Cloud) and GR 290 (also in M33). Whereas these two LBVs exhibited B-type spectra in eruption, MCA-1B is the first clear case where a Wolf-Rayet (WR) spectrum persisted at all times. Together, MCA-1B, HD 5980, and GR 290 constitute a class of WN-type LBVs, distinct from S Doradus LBVs. They are most interesting in the context of LBVs at low metallicity, a possible post-LBV/WR transition in binaries, and as likely Type Ibn supernova progenitors.

show abstract

Section: Introductionmentioning

confidence: 99%

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

Smith

Andrews

Moe

et al. 2020

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…Ostars and B-supergiants are H-and very early He-burning massive stars, younger than 30 Myr (e.g. Massey 2013). They pinpoint star formation in both space and time and can inform current efforts to understand the nature and fuel of star formation in dwarf galaxies.…”

Section: Introductionmentioning

confidence: 99%

Ongoing star formation at the outskirts of Sextans A: Spectroscopic detection of early-O type stars.

García

Herrero

Najarro

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

With both nebular-and stellar-derived abundances of 1/10 Z ⊙ and low foreground extinction, Sextans A is a prime candidate to replace the Small Magellanic Cloud as reservoir of metal-poor massive stars and reference to study the metal-poor Universe. We report the discovery of two early-O type stars in Sextans A, the earliest O-stars with metallicity <1/7 Z ⊙ known to date, and two additional O9 stars. Colour-excess estimates towards individual targets, enabled by spectral typing, manifest that internal reddening is neither uniform nor negligible. The four targets define a new region of star formation far from the opticallybrightest centre of the galaxy and from its conspicuous H ii shells, but not devoid of neutral hydrogen. In fact, we detect a spatial correlation between OB-stars and H i in Sextans A and other dIrr's that leads us to propose that the neutral phase may be fundamental to star formation in low-density environments. According to the existing evidence at least two of the targets formed in isolation, thus suggestive of an stochastic sampling of the initial mass function that would enable low-mass galaxies like Sextans A to form very massive stars. The discovery of these four stars provide spatially-resolved, spectroscopic confirmation of recent findings suggesting that dwarf galaxies can sustain star formation despite the low density of the gas phase.

show abstract

“…I also refer the reader to the Handbook of Star-forming Regions (Reipurth 2008a(Reipurth , 2008b, where a wealth of information is provided about giant star-forming regions (or star-forming complexes) in the Milky Way. Recommended review articles concerning OB associations in galaxies of the Local Group are those focusing on two topics that will not be sufficiently addressed here, namely their massive stellar content (Garmany 1994;Massey 2013) and the corresponding IMF (Massey 1998).…”

Section: Introductionmentioning

confidence: 99%

Unbound Young Stellar Systems: Star Formation on the Loose

Gouliermis¹

2018

PASP

View full text Add to dashboard Cite

Unbound young stellar systems, the loose ensembles of physically related young bright stars, trace the typical regions of recent star formation in galaxies. Their morphologies vary from small few pc-size associations of newly formed stars to enormous few kpc-size complexes composed of stars few 100 Myr old. These stellar conglomerations are located within the disks and along the spiral arms and rings of star-forming disk galaxies, and they are the active star-forming centers of dwarf and starburst galaxies. Being associated with star-forming regions of various sizes, these stellar structures trace the regions where stars form at various length-and timescales, from compact clusters to whole galactic disks. Stellar associations, the prototypical unbound young systems, and their larger counterparts, stellar aggregates, and stellar complexes, have been the focus of several studies for quite a few decades, with special interest on their demographics, classification, and structural morphology. The compiled surveys of these loose young stellar systems demonstrate that the clear distinction of these systems into welldefined classes is not as straightforward as for stellar clusters, due to their low densities, asymmetric shapes and variety in structural parameters. These surveys also illustrate that unbound stellar structures follow a clear hierarchical pattern in the clustering of their stars across various scales. Stellar associations are characterized by significant sub-structure with bound stellar clusters being their most compact parts, while associations themselves are the brighter denser parts of larger stellar aggregates and stellar complexes, which are members of larger superstructures up to the scale of a whole star-forming galaxy. This structural pattern, which is usually characterized as self-similar or fractal, appears to be identical to that of star-forming giant molecular clouds and interstellar gas, driven mainly by turbulence cascade. In this short review, I make a concise compilation of our understanding of unbound young stellar systems across various environments in the local universe, as it is developed during the last 60 years. I present a factual assessment of the clustering behavior of star formation, as revealed from the assembling pattern of stars across loose stellar structures and its relation to the interstellar medium and the environmental conditions. I also provide a consistent account of the processes that possibly play important role in the formation of unbound stellar systems, compiled from both theoretical and observational investigations on the field.

show abstract

Massive stars in the galaxies of the Local Group

Cited by 35 publications

References 124 publications

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

A new and unusual LBV-like outburst from a Wolf–Rayet star in the outskirts of M33

Ongoing star formation at the outskirts of Sextans A: Spectroscopic detection of early-O type stars.

Unbound Young Stellar Systems: Star Formation on the Loose

Contact Info

Product

Resources

About