Massive star formation
Massive stars are thought to form by accretion, during the gravitational collapse of dense cores in large interstellar clouds. Their properties at birth, such as their mass and angular momentum, rely on the complex hydrodynamics of the collapse.
Due to their high luminosity, massive stars exert a strong radiative feedback on the surrounding gas and dust during their formation. In particular, their ultraviolet radiation field usually ionises large regions in their vicinity, which might disrupt the accretion process. However, the ionising flux depends significantly on the accretion process. [Haemmerlé et al. 2016, A&A 585 A65; Haemmerlé & Peters 2016, MNRAS 458 3299; Haemmerlé et al. 2019, A&A 624 A137; Meyer et al. 2019, MNRAS 484 2482; Meyer et al. 2019, MNRAS 487 4473; Jaura et al. 2022, MNRAS 512 116]
By angular momentum conservation, accretion is expected to proceed through a disc. Mechanisms like magnetic fields, viscosity, or gravitational torques are required in order to remove angular momentum from the central regions, otherwise the star would rotate so fast that the centrifugal force would overcome gravity and destroy the star. For the gas to be accreted by the star, these mechanisms must be efficient enough to remove more than 2/3 of the angular momentum from the inner disc. [Haemmerlé et al. 2017, A&A 602 A17]
Supermassive stars: the most massive stars in Universe's history?
The recent discovery of quasars at high redshifts, powered by supermassive black holes of millions to billions solar masses, challenges our understanding of the early Universe. The accumulation of such masses in a compact object in less than a billion years requires extreme conditions. The most promising scenario for the formation of these black holes is the direct collapse of interstellar matter into a supermassive star, and the subsequent collapse of the star via the general-relativistic instability. [Haemmerlé et al. 2020, SSR 216 48; Haemmerlé 2021, A&A 647 A83; Haemmerlé 2020, A&A 644 A154; Haemmerlé 2021, A&A 650 A204; Haemmerlé et al. 2021, A&A 652 L7; Zwick et al. 2023, MNRAS 518 2076; Haemmerlé 2024, accepted in A&A]The high energies involved in the collapse of supermassive stars could trigger the emission of detectable gravitational waves and ultra-long gamma-ray bursts. However, these observational signatures are sensitive to the rotational properties of the star, which depend on the accretion process. [Haemmerlé et al. 2018, ApJ 853 L3; Haemmerlé & Meynet. 2019, A&A 623 L7; Haemmerlé 2021, A&A 650 A204; Haemmerlé 2023, MGM 16 2865]
Publication list:
Haemmerlé 2024, accepted in A&A
Haemmerlé 2023, MGM 16 2865
Haemmerlé et al. 2021, A&A 652 L7
Haemmerlé 2021, A&A 650 A204
Haemmerlé 2021, A&A 647 A83
Haemmerlé 2020, A&A 644 A154
Haemmerlé et al. 2020, SSR 216 48
Haemmerlé et al. 2019, A&A 632 L2
Haemmerlé et al. 2019, A&A 624 A137
Haemmerlé & Meynet. 2019, A&A 623 L7
Haemmerlé et al. 2018, MNRAS 474 2757
Haemmerlé et al. 2018, ApJ 853 L3
Haemmerlé et al. 2017, A&A 602 A17
Haemmerlé & Peters 2016, MNRAS 458 3299
Haemmerlé et al. 2016, A&A 585 A65
Haemmerlé 2014, PhD thesis
Haemmerlé et al. 2013, A&A 557 A112
Salmon et al. 2022, A&A 664 L1
Martinet et al. 2022, A&A 664 A181
Jaura et al. 2022, MNRAS 512 116
Eggenberger et al. 2021, A&A 652 A137
Murphy et al. 2021, MNRAS 501 2745
Bastian et al. 2020, MNRAS 495 1978
Holgado et al. 2020, A&A 638 A157
Woods et al. 2020, MNRAS 494 2236
Martins et al. 2020, A&A 633 A9
Woods et al. 2019, PASA 36 e027
Meyer et al. 2019, MNRAS 487 4473
Meyer et al. 2019, MNRAS 484 2482
Villebrun et al. 2019, A&A 622 A72
Surace et al. 2019, ApJ 869 L39
Rao et al. 2018, A&A 618 A18
Boekholt et al. 2018, MNRAS 476 366
Woods et al. 2017, ApJ 842 L6
Granada & Haemmerlé 2014, A&A 570 A18
Georgy et al. 2013, A&A 558 A103
Eggenberger et al. 2012, A&A 539 A70