Research

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Research Interests

The main interests of this research group is to study massive stars in a variety of environments, and so overlaps with other Sheffield astrophysics research groups involving studies of core-collapse supernovae, star clusters and starbursts.

Joachim Bestenlehner is analysing the massive star populations in the Milky Way and Magellanic Clouds, including VLT/MUSE integral-field observations of NGC2070 in the LMC. Thaer Kousa starts his PhD studies on ULLYSES/XshootU datasets in Oct 2022. Gemma Rate has previously studied Wolf-Rayet stars with ESA GAIA (PhD completed in Dec 2020), Katie Tehrani (PhD completed in Nov 2019) investigated Wolf-Rayet stars at X-ray and optical wavelengths with honourary researcher Andy Pollock.

We are also involved in the WHT/WEAVE galactic plane Stellar, Circumstellar and Interstellar Physics (SCIP) survey, while Bestenlehner is a member of the upcoming VISTA/4MOST spectroscopic surveys of the Magellanic Clouds 1001MC.

R136 star cluster

Ultraviolet HST/STIS spectroscopy of the young, rich star cluster R136 is available in ASCII format (figure 12 from MNRAS paper, erg/s/cm^2/Ang):

We have recently undertaken spectral analyses of these stars from HST/STIS optical spectroscopy (see MNRAS paper). Former students/postdocs are still involved in our research projects, notably Dr Saida Caballero-Nieves (FIT) involving massive binaries and the R136 star cluster, plus Dr Joanne Pledger (nee Bibby) (UCLan) who is involved with studying Wolf-Rayet populations in nearby star forming galaxies.

Large and Small Magellanic Clouds

Template optical spectra of Wolf-Rayet stars in the LMC and SMC are available in ASCII format, below.

Large Magellanic Cloud

Small Magellanic Cloud

Galactic Wolf-Rayet catalogue

We host a Galactic Wolf-Rayet catalogue. Template optical spectra of Milky Way Wolf-Rayet stars will follow based on GAIA EDR3 results. Until then, templates have been produced based on estimated distances – primarily from this article.

Nitrogen sequence

Carbon sequence

Current projects

HST/Director: ULLYSES (Hubble UV Legacy Library of Young Stars as Essential Standards) plus XShootU (ULLYSES and XShooter massive stars collaboration).

HST/Cycle 28: GULP (Galaxy UV Legacy Project, PI: E. Sabbi, 88 orbits).

Chandra/Cycle 15: The Tarantula Revealed by X-rays (T-ReX): A definitive Chandra investigation of 30 Doradus (PI: L. Townsley, 2Msec).

HST/Cycle 20+22: Proper motions of isolated massive stars near the Galactic Centre (GO 12915, PI: D. Lennon, 18+18 orbits).

HST/Cycle 19+20: A massive star census of the starburst cluster R136 (GO 12465+13052: PI: P. Crowther, 32+7 orbits).

Herschel/OT2: Oxygen abundances in carbon-type Wolf-Rayet stars from PACS scan spectroscopy (PI: P. Crowther, 7.7 hours).

HST/Cycle 19: Weighing the most luminous main-sequence star in the Galaxy (GO 12615: PI: O. Schnurr, 14 orbits).

HST/Cycle 19+21: Proper motions of massive stars in 30 Doradus (GO 12499: PI: D. Lennon, 15+15 orbits).

VLT/Large Programme: VLT/FLAMES Tarantula Survey (PI: Chris Evans)