• NEANIAS Space Research Community

Within this thesis, we present an extended multiwavelength analysis of the rich massive Galactic star-forming complex G305. We have focused our attention on studying the both the embedded massive star-forming population within G305, while also identifying the intermediate-, to lowmass content of the region also. Though massive stars play an important role in the shaping and evolution of their host galaxies, the physics of their formation still remains unclear. We have therefore set out to studying the nature of star formation within this complex, and also identify the impact that such a population has on the evolution of G305. We firstly present a Herschel far-infrared study towards G305, utilising PACS 70, 160 μm and SPIRE 250, 350, and 500 μm observations from the Hi-GAL survey of the Galactic plane. The focus of this study is to identify the embedded massive star-forming population within G305, by combining far-infrared data with radio continuum, H2O maser, methanolmaser,MIPS, and Red MSX Source survey data available from previous studies. From this sample we identify some 16 candidate associations are identified as embedded massive star-forming regions, and derive a two-selection colour criterion from this sample of log(F70/F500)! 1 and log(F160/F350)! 1.6 to identify an additional 31 embedded massive star candidates with no associated starformation tracers. Using this result, we are able to derive a star formation rate (SFR) of 0.01 - 0.02 M! yr−1. Comparing this resolved star formation rate, to extragalactic star formation rate tracers (based on the Kennicutt-Schmidt relation), we find the star formation activity is underestimated by a factor of !2 in comparison to the SFR derived from the YSO population. By next combining data available from 2MASS and VVV, Spitzer GLIMPSE and MIPSGAL, MSX, and Herschel Hi-GAL, we are able to identify the low-, to intermediate-mass YSOs present within the complex. Employing a series of stringent colour selection criteria and fitting reddened stellar atmosphere models, we are able remove a significant amount of contaminating sources from our sample, leaving us with a highly reliable sample of some 599 candidate YSOs. From this sample, we derive a present-day SFR of 0.005±0.001M! yr−1, and find the YSOmass function (YMF) of G305 to be significantly steeper than the standard Salpeter-Kroupa IMF. We find evidence of mass segregation towards G305, with a significant variation of the YMF both with the active star-forming region, and the outer region. The spatial distribution, and age gradient, of our 601 candidate YSOs also seem to rule out the scenario of propagating star formation within G305, with a more likely scenario of punctuated star formation over the lifetime of the complex.

ORION2 version 1.0 code release. The code description is published in a companion JOSS publication (10.21105/joss.03771).

The utility of complex organic molecules as probes of star formation and astrophysical environments depends on understanding of complex chemistry in protostellar environments. Existing protostellar models of hot core chemistry predict very low abundances of ethylene glycol, (CH2OH)2, a very large and hydrogen rich complex molecule, in star-forming regions. However, recent observations of Comet Hale-Bopp and Central Molecular Zone (CMZ) clouds have suggested that (CH2OH)2 can be produced in higher quantities than previously assumed. However, since these sources have extreme environmental conditions that complicate analysis of the chemistry, we cannot directly compare these results to current model predictions. As such, we examine 16 GHz of spectra from high mass young stellar object (YSO) NGC 7531 IRS 1 from the IRAM 30m telescope to determine the molecular abundance and excitation temperature of (CH2OH)2. Since NGC 7538 IRS 1 is an archetypal hot core, we can directly test current model predictions and benchmark the relative importance of different stages of star formation region complex chemistry. The column density and excitation temperature is calculated in two ways: by qualitative fitting of the most promising line candidates and via the rotation diagram method. We find that current models strongly underestimate (CH2OH)2, providing the first indication that (CH2OH)2 is much more common in star-forming regions. Since laboratory experiments have linked (CH2OH)2 to warm ice photochemistry, the results imply that this stage in star formation and the formation pathways of very complex molecules such as (CH2OH)2 are of greater relative chemical importance than previously assumed.

The CSI 2264 project performed photometric monitoring of young NGC 2264 cluster members using the Spitzer Infrared Array Camera (IRAC; Fazio et al. 2004) and the Convection, Rotation and Planetary Transits satellite (CoRoT; Baglin et al. 2006) simultaneously. Thirteen other telescopes monitored the region at different times concurrently with (or closely in time to) the primary Spitzer and CoRoT joint campaign. The CSI 2264 project is described in detail in Cody et al. (2014). This table contains CoRoT light curves for objects that are very likely NGC 2264 members (using the criteria described in Cody et al. 2014). There are many rows for each object, because each object has many epochs of data. There are 9 columns in this table, as follows. Columns 7, 8, and 9 (the IRAC excess flag and the light curve types) are duplications of information found in the Object Table, but are repeated here to make it easy for users to, e.g., pull out all of the light curves of a specific type. To access this resource via TAP, issue ADQL queries on the table named csi2264t2.