**2. Tarantula Nebula**

The Tarantula Nebula is the most striking star-forming region in the LMC, whether viewed in the far ultraviolet (hot, luminous stars), H*α* (ionized gas) or mid-IR (warm dust), extending over several hundred parsec, owing to a massive stellar content producing an ionizing output which is a thousand-fold higher than the Orion Nebula [4].

NGC 2070 is the dominant ionized region within the Tarantula Nebula, powered by a large number of hot luminous stars from R136 at its heart plus many more within its vicinity. NGC 2060, located 6 arcmin (90 pc) to the southwest, is host to a more modest population of OB stars plus an X-ray pulsar PSR J0537-6910 and its supernova remnant (SNR) N157B. Hodge 301 is located 3 arcmin (45 pc) to the north west of R136, but does not possess significant nebulosity since previous supernovae are likely to have cleared this region of gas, and its stellar population (B-type stars and red supergiants) does not possess a significant Lyman continuum output. NGC 2070 is often referred to as a cluster in the literature but it extends over tens of parsecs whereas genuine star clusters are an order of magnitude smaller, such that the only rich star clusters within the Tarantula are R136, with an age of 1–2 Myr [5] and Hodge 301 with an age of 20–30 Myr [6] with a few additional lower mass young, compact clusters (e.g., TLD1, SL 639). Table 1 compares various regions within the Tarantula Nebula, adapted from a previous review by Walborn [7]. Although the focus of the present review is on spectroscopic results for massive stars, Sabbi et al. [8] have undertaken a deep Hubble Space Telescope (HST) multi-colour photometric survey, known as the Hubble Tarantula Treasury Project (HTTP) which permits lower mass stars in the Tarantula Nebula to be studied.


**Table 1.** Physical scales within the Tarantula Nebula, adapted from Walborn [7]. Ionizing outputs, N(LyC) are obtained from the present work.

A number of complementary studies of the star formation history of the Tarantula Nebula have been carried out, exploiting pre-main sequence low mass stars [13,14] and massive stars [15]. Significant star formation commenced ∼25 Myr ago, as witnessed by Hodge 301, and reached a peak several Myr ago, with the young massive star cluster R136 at its heart no more than 2 Myr old. It is apparent that star formation within the Tarantula Nebula has not been limited to specific parsec-scale star clusters, such as Hodge 301 or R136, but has been distributed across the entire region, akin to a super OB association. Wright et al. [16] have established from proper motion observations that star formation in the far smaller Milky Way Cygnus OB2 region did not originate in a star cluster, but involved individual sub-regions in virial equilibrium. Indeed, median ages of massive stars show little radial dependence on their projected distance from R136, with very massive stars (≥100*M*) identified throughout the region [15]. Infrared and radio observations of the Tarantula reveal ongoing regions of massive star formation, to which the reader is referred to the review by Walborn [17] and a more recent study of the brightest embedded sources based on Spitzer/IRAC imaging [18]. Atacama

Large Millimetre Array (ALMA) has obtained high resolution observations of parsec-scale clumps within the Tarantula [19], with the rate of star formation in the Tarantula anticipated to decline in the future.
