Swinburne Astronomy Online

Project Cover Sheet

Student Name Sarah Pearce Student ID 100 280 899

Current Year 2016 Semester 1 = Feb.-June or 2 = July-Nov.

SAO Unit AST80016

Project ID 073

Project Supervisor Prof. Jeremy Mould

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main text

10

Total page count 16

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Name: Sarah Pearce

The ISM

The Interstellar medium (ISM) is composed of the dust and gas between stars. Composed of

mostly hydrogen (70%) and helium(27%) with small dust grains. Stars are formed in molecular

colder, denser regions of the ISM ( Smith,G., 1999). Dust absorbs light, causing reddening

effects, however spectral lines do not shift and we are able to see through the ISM in the infrared.

Dust grains are of a complex shape, preferentially absorbing shorter wavelengths. At the site of a

newborn star, photoevaporation takes place which is a process within a molecular cloud in the

vicinity of a newborn hot star where the cloud itself is dispersed by the star's radiation ( Smith,G.

1999).

Nebulae- emission nebulae H 11 regions

An H 11 region is a region of interstellar space that possesses atomic hydrogen that is ionized. It

is part of a cloud in which recent star formation has taken place. H 11 regions are often

associated with molecular clouds and appear clumpy and filamentary. H 11 regions may give

birth to thousands of stars over a period of several million years (Flynn,C., 2005). They are the

emission nebulae sites of active star formation. The precursor to an H 11 region is a giant

molecular cloud with cold dense gases, mostly molecular hydrogen. H 11 regions are only found

in spiral and irregular galaxies (Flynn,C., 2005).

.

Figures 1 and 2: Star and protostar formation. Source: URL: http://abyss.uoregon.edu/~js/ast122/lectures/lec13.html

Molecular clouds

Molecular clouds are sometimes called stellar nurseries and are a type of interstellar cloud.

Within molecular clouds are denser regions called clumps, where star formation is taking place.

The formation of stars occurs exclusively within molecular clouds (Schombert, J., 2016). They

have low temperatures and high densities, where gravitational forces act to collapse the cloud

and ignite a star. The internal motions of the clouds are ruled by turbulence in a cold magnetized

gas, often being the home of astronomical masers (Schombert, J., 2016).

Protostars

The inner regions surrounding the envelopes of protostars are characterized by a complex

chemistry, with prebiotic molecules present where protoplanetary disks (proplyds) may form

(Jorgensen et al., 2016). The interplay between ejection and accretion of matter is thought to be

of critical importance in the formation of stars (Louvet, et al., 2016). Gravitational collapse in

spiral compressed gas occurs. Hubble Space Telescope (HST) used their Wide Field Planetary

Camera to discover several externally ionized proplyds (Ricci, et al., 2008). So far a total of over

200 silhouette disks and bright proplyds have been revealed by the HST observations of the

Orion Nebulae. The majority of which have been revealed by narrowband filters centered on the

H a λ 6563 emisssion lines ( Ricci et al., 2008). The protostellar phase ends when infall stops.

Figures 3 and 4: star birth evolution and stages of star evolution within a molecular cloud. Source: https://www.mpi-

hd.mpg.de/sed2011/talkarchive/Bruce_Elmegreen_IAU284.pdf

Pre-main sequence evolution

Pre-main sequence stars (PMS) are in transition between protostars and the main sequence. The

pre-main sequence in the direct continuation of the protostellar phase (Stolte, 2016). PMS stars

are observed in young star clusters and young associations. T Tauri stars are the youngest visible

F, G, K and M spectral type of stars which are less than 2 solar masses. Although their surface

temperatures are similar to main sequence stars of the same mass, their larger radii cause them to

be significantly more luminous. These young stars have a central temperature too low for

hydrogen fusion to take place, rather they are powered by gravitational energy as the stars

contract, on their journey towards the main sequence after about 100 million years (Stolte, 2016).

Pre-main sequence evolution is governed by temperature and density changes which lead to

changes in the dominant opacity contribution with stars alternating between convective and

radiative phases (Stolte, 2016). A star's journey onto the Hertzsprung- Russel diagram depends

on it's stellar mass. Sun like stars develop radiative cores during the Hayashi phase. While more

massive stars develop convective cores during the Henyey phase which is radiatively driven. The

PMS evolution of a star is determined by the Kelvin-Helmholtz timescale. The amount of time

spent on the pre main sequence depends on the mass of the star.

Figures 5 and 6: The Hertzsprung-Russel diagram and the radiative and convective tracks of PMS stars. Source:

https://astro.uni-bonn.de/~astolte/StarFormation/Lecture2012_PMS.pdf

Figure 7: Convective vs radiative phases on the pre main sequence. Source: https://astro.uni-

bonn.de/~astolte/StarFormation/Lecture2012_PMS.pdf

Star formation triggers

Star formation triggers include H a at the edges of shells is known to be triggered or lingering

star formation. Pillars and bright rims form by the push back of interclumped gas (Elmegreen,

2011). The best triggering mechanisms for star formation produce high densities for long

periods and include: kinetic energy in the ISM, rotational energy in the ISM, self-gravity energy

sources, H 11 regions winds and multiple SNe, H11R and winds. Filament collapse is a common

mode of star formation. Triggering is a detail of gas dynamics on smaller scales (Elmegreen,

2011). Triggering processes include: within spiral arms of galaxies, gravitational collapse of

compressed gas with complex shock dynamics. Shells and rings undergoing gravitational

collapse in expanding, accreting geometries with complex shock dynamics. Pillars and bright

rims possess pressurized pieces of gas clouds. Star formation rates depend on the total mass of

cold gas (Elmegreen, 2011).

B) ATLASGAL

ATLASGAL is a survey by APEX, the Atacama Pathfinder experiment telescope, located on the

Chajnantor Plateau in Chile's Atacama region, 5100 meters above sea level. This survey took

advantage of the telecsope's unique attributes to provide a detailed view of the distribution of

cold and dense gas along the plane of the Milky Way galaxy. The new image survey includes

most of the regions of star formation in the southern Milky Way. The survey is the single most

successful APEX programme with over 70 associated science papers already published, now

expanding it's reach even further with reduced data products available to the full astronomical

community. Central to APEX's success are it's sensitive instruments, including the Large

Bolometer Camera (LABOCA) that was used for the ATLASGAL survey. LABOCA measures

incoming radiation by registering the minute rise in temperature it causes on its detectors and can

detect emission from the dark cold dust bands obscuring the stellar light (ATLASGAL, 2016).

The map was constructed from individual APEX observations of radiation with a wavelength of

870 um. This survey provides insights into where the next generation of stars and clusters form.

By using these observations in conjunction with observations from the Planck telescope, further

insights into the large scale structures of giant molecular clouds can be researched. APEX is a

collaboration between the Max Planck Institute for Radioastronomy (MPIfR), the Onsala Space

Observatory (OSO) and the European Southern Observatory to construct and operate a modified

ALMA prototype antenna as a single dish. APEX has a suite of heterodyne spectrometers and

wide-field bolometer cameras operating in the majority of atmospheric windows from 0.2 to 1.4

mm.

HOPS

Hops is a project led by Dr. Andrew Walsh in collaboration with Dr. Steven Longmore and Dr.

Cormac Purcell. HOPS stands for The H2O southern Galactic Plane Survey. Using the MOPRA

spectrometer (MOPS) they were able to cover 16 different frequency bands simultaneously.

Methanol lines that are known masers are indicated in table columns. They observed a total of

100 square degrees over three seasons.

GLIMPSE

GLIMPSE stands for Galactic Legacy Infrared Midplane Survey Extraordinaire. It is the use of

the Spitzer space telescope to survey the inner Milky Way in the infrared. The GLIMPSE survey

spans 130 degrees in longitude and 2-4 degrees in latitude, actually encompassing a large

fraction of the volume of our galaxy. The Spitzer telescope was pointed to 111, 000 different

positions in the sky and took images in four different infrared wavelengths (3.6, 4.5, 5.8 and 8

um), creating a total of 444 000 images. At infrared wavelengths dust particles are less opaque

and the heated dust is able to be imaged, due to both the resolution of the Spizer space telescope

and the sensitivity of it's instruments, this survey has allowed us to see stars and dusty objects for

the first time for most of our galaxy.

MIPSGAL

The MIPSGAL survey is an extensive infrared investigation into the Galactic plane of the Milky

Way using the Spitzer space telescope. This survey uses infrared light to observe clumps of gas

collapsing to form protostars. It also uses the infrared to peer through gas and dust obscuring the

view to the centre of the galaxy. The MIPSGAL survey is designed to in particular identify all of

the massive protostars forming in our galaxy. It was also designed to map all the dust and where

it is distributed on the plane of our galaxy. The MIPSGAL survey encompasses 278 square

degrees of the inner Galactic plane which allows for a dataset focused on answering questions

about the interstellar dust in our galaxy and how the most massive stars are formed. The

majority of stars, gas and dust that make up our galaxy are covered in this survey. One study into

the millimeter-sized grains in the protostellar envelope looks at grain growth during star

formation and how it affects the physical and chemical processes in the evolution of star-forming

clouds (Wong et al., 2016).

HiGAL

HiGAl is the Herchel infrared Galactic Plane Survey and is an Open Time Key Project to map

the inner Milky Way galaxy in five bands between 60 and 600 microns with diffraction limited

spatial resolution. This survey provides a single homogeneous dataset with a census of

temperature, luminosity, mass and spectral energy distributions in star forming regions. It also

maps the same for cold ISM structures in all galactic environments for scales ranging from

massive objects in protoclusters to the full spiral arm. A study of the feedback of atomic jets

from embedded protostars in NGC 1333 uses Herchel data to uncover key understanding

regarding star-formation, in particular the star formation feedback onto the parent cloud

(Dionatos and Gudel, 2016). Another study using HiGal data is regarding the segregation of

starless and protostellar clumps in a particular region of the sky. Providing images of the

filamentary structure of the parent molecular clouds on large scales which allows for the the

study of the physical connection between the clumps/cores and the filaments (Olmi et al., 2016).

PILS

The ALMA Protostellar Interferometric Line Survey is a survey of the inner regions of the

envelopes surrounding young protostars (Jorgensen et al., 2016). They are characterized by a

complex chemistry, with prebiotic molecules present on the scales where protoplanetary disks

may eventually form (Jorgensen et al., 2016). ALMA provides an unprecedented view of these

regions zooming in to solar system scales to provide images of nearby protostars while mapping

the emission from rare species (Jorgensen et al., 2016). Another study using ALMA's data looks

at the interplay between the accretion and ejection of matter which is thought to be a critical

element in the formation of stars (Louvet, et al. 2016). However, the exact link between jets and

accretion disks is still a critical issue in contemporary astrophysics (Louvet, et al., 2016).

Further, ALMA data is used to study the morphology and kinematics of the gas envelopes of

protostars, and to establish the conditions for in-falling cool gas onto rotating disks surrounding

protostars, learning that different molecules populate different radial regions (Tuan-Anh, et al.,

2016) . Even further studies reveal the dynamics of Class 0 protostellar disks using ALMA data.

A class 0 protostellar disk is the earliest, embedded stage of protostellar evolution, hinting

towards these disks from the onset of protostellar formation (Seifried, et al., 2016). ALMA data

has also been used to detect a hot molecular core in the Large Magellanic Cloud, by pointing

towards a high-mass yound stellar object in a nearby low metallicity galaxy (Shimonishi et al.,

2016)

C) telescopes and detectors: focus on the imaging tools of star formation regions, young stellar

objects and protostars

Optical telescopes

HST

The Hubble Space Telescope's new Wide Field Camera 3 (WFC3) was designed to make

infrared observations. The HST can image in the visible then also image in the infrared once they

have detected a star birth region. In the Orion Nebula, is a region of star formation here in the

Milky Way. Hubble was able to reveal and image over 200 proplyds (Ricci et al, 2008), which

are disks of dust around newly born stars and the location of where planets are thought to form.

When the HST images in infrared, the dust fades leaving only the location of where the star birth

activity is taking place. The instrument has two channels, one for UV and visible light and the

other for near infrared (NIR). In both cases the devices are solid state CCDs. The combination of

these two devices allows for wider performance over a broader range of wavelengths. This

allows astronomers to locate the actual sites of star formation.

Infrared telescopes

The Spitzer space telescope operates in the infrared region of the spectrum. It exposes regions of

star birth in nebulas otherwise obscured by dust. Strings of stars that have yet to burn their way

through their gas shells can be pinpointed using the Spitzer telescope. The GLIMPSE survey

was undertaken using the Spitzer space telescope and it imaged the majority of our galaxy. It was

able to uncover numerous regions of star birth and peer through the dust allowing for the process

of star birth to be better understood. The telescope has wavelength coverage from 3-180 microns,

spectroscopy from 5-40 microns and spectrophotometry from 50-100 microns. This telescope is

in an Earth - trailing, Heliocentric orbit with an 85 cm diameter. This telescope has been used to

study young stellar objects, in particular in Canis Major. Spitzer data can be used to identify new

stellar objects (YSOs) over the entire sky (Fisher et al., 2016) Newly identified YSOs may

refine the initial stellar mass function, allowing for a better characterization of star and planet

formation in regions with low initial gas densities and identify sites nearby for high resolution

imaging and spectroscopy follow up (Fisher at al., 2016).

Ground based radio astronomy telescopes

ALMA

The Atacama Large Millimeter/Submillimeter Array (ALMA) is an international collaboration

between the European Southern Observatory (ESO), the National Institutes of Natural Sciences

(NINS) of Japan, the US National Science Foundation and NRC (Canada) with NSC and ASIAA

(Taiwan) and KASI (Republic of Korea) in cooperation with the Republic of Chile. It is

composed of 66 high precision antennas located on the Chajnantor plateau, 5000 meters altitude

in Chile and is the largest astronomical project in existence. ALMA works on the notion of

interferometry, where signals captured are combined and thus obtain information about their

source such as a star, planet or galaxy (Hales et al., 2016). With the combination of signals for

several antennas it is possible to construct images. The images ALMA produces are as good as

one hypothetical telescope 14 000 meters in diameter (Hales et al., 2016). Hence the combination

of several (66) antennas to construct one giant telescope. To operate properly all of ALMA's 66

antennas and electronics need to be acting in synchronicity, with the precision of one millionth of

a millionth of a second (Hales et al., 2016). Further, the signals from all of the different antennas

must be combined in a way such that the paths of the signals must be known to an accuracy of

hundredths of a millimeter before they are finally combined by the central computer known as

the correlator. Further complicating things are the noise contributions to the signal such as the

atmosphere which must later be corrected for. ALMA has seven weather stations, with specially

built water vapor radiometers, to correctly characterize the contributions of the atmosphere to the

signal noise (Hales et al., 2016). Radio waves undergo a chain of channeling, reception,

conversion, transmission, combination and analysis after having travelled through space for

millions of years. Antennas: function to capture and concentrate the radio waves proceeding

from the astronomical source at the point known as the focus (Hales et al., 2016). The way

ALMA's antennas then send the light concentrated at the focus to a subreflector, by reflecting the

light which is a point behind the parabolic surface, where there is a receiver designed to capture

the signal concentrated by the antenna (Hales et al., 2016). In order to capture the largest amount

of radio waves, in order to optimize the signal received, ALMA's antennas must aim with unique

precision. This is achieved by ensuring that the antennas must not deviate from a perfect

parabola by more than 20 microns on average (Hales et al., 2016). The front end is the name

given to the beginning of the detection, amplification, conversion and digitization of the signal

picked up by each antenna. The most critical components of the front end are kept at a

temperature of - 269 degree Celsius to reduce noise (Hales et al., 2016). The front end

technologies have been developed in laboratories in Japan, France, the Netherlands, the UK,

Canada and the USA. Firstly the signal from the subreflector is tunneled through a series of

small mirrors and waveguides to the cold components where the detectors reside (Hales et al.,

2016). The signal is then mixed with a reference signal designed to lower it's frequency. This

lower frequency signal is more easily amplified and processed by the transmission and

digitization system called the back end that will send the data to the correlator over as much as

15 km of fiber optic cable (Hales et al., 2016). ALMA is used in 10 frequency bands, whereby

there are 10 cartridges per antenna, one per band. The back end acts as the nervous system of

ALMA, transmitting the signal received at each of the receivers in each antenna to the central

computer called the correlator. First, the signal from the front end is again converted to an even

lower frequency, between 7.5 to 15 cm, then a digitization system processes the signal and

transmits it underground via fiber optic to the central building (Hales et al., 2016). In addition to

transmitting the signal to the correlator the back end acts as overall orchestra conductor, sending

out a reference bar to ensure that all ALMA components: the antenna movements, electronics

and hydrogen atomic clocks located in the central building, are in unison by the back end that

generates a reference pulse it sends out to all the components (Hales et al., 2016). Further, the

back end also sends out a round-trip laser signal to all the antennas to ensure the length of the

fiber optic cables which can expand and contract due to temperature variations at the site. Any

changes to the length of the fibres are compensated with real-time stretching or contracting of the

fiber. This is called the Line Length Correction system and it ensures the stability of the signal

path length to approximately one micron (Hales et al., 2016). The correlator is ALMA's brain, a

supercomputer custom designed for taking the signals form ALMA's antennas and combining

them in order to generate astronomical datasets for later analysis. The correlator multiplies the

signals from the multiple antennas and saves the data as files called Visibilities, which contain all

the information required to form a 2-D image and the spectral information of the region of the

sky observed (Hales et al., 2016). The processing of the data to become a Visibilities file

requires a number of calibration and data reduction stages for which a specialized data reduction

program has been created. Computing IPT (CIPT) is in charge of all of ALMA's information

processing, handling all the software required to control the antennas, instrumentation and data

filling(Hales et al., 2016). Further, CIPT is in charge of providing all the software for the

scientific community to use for preparing observations, as well as a specialized software for data

processing and reduction known as Common Astronomy Software Application (CASA) (Hales

et al., 2016). Science IPT is ALMA's team for performing the scientific verification of the data

obtained. It ensures the scientific validity of the datasets, by carrying out all the calibrations and

verifications to check that all items of equipment are operating according to the ALMA technical

and scientific requirements (Hales et al., 2016).

Researchers use ALMA data in conjunction with Herschel and Caltech submillimeter

Observatory (CSO) to study star formation and feedback, molecular outflows and how they

interact with prestellar cores. Low mass star formation is known to occur exclusively in the

shielded interiors of molecular cloud cores, when gravity fights for control from supporting

thermal, magnetic and turbulent pressures, collapse ensuing (Lis et al., 2016). Significant effort

has been placed on understanding the subsequent stages of star formation, when a central object

and surrounding circumstellar disk are formed and evolve towards a new star and potentially an

associated planetary system (Lis et al., 2016). However, initiation of this process is among the

least understood steps of star formation. However, it is key to understand and refine fundamental

aspects such as the initial mass function, the binarity fraction and it's dependence on both stellar

mass and the star formation efficiency (Lis et al., 2016).

Figure 8 : Protoplanetary disk around a newborn star by ALMA. Source:

https://en.wikipedia.org/wiki/Atacama_Large_Millimeter_Array.

This was a key finding for ALMA's contribution to the research of stellar birth because nobody

expected protoplanet formation around such a young star, whereby new theories emerged about

the formation of protoplanets around 100 000 - 1 000 000 year old systems. ALMA imaging

instruments function in all atmospheric windows between 350 um and 10 mm. This makes it

possible for ALMA to directly observe star birth regions. This image of a protoplanetary disk

was observed surrounding a very young T Tauri star and shown to the public in 2014.

Much of the insight into structure of starless cloud cores comes from observations of the

millimeter dust emission. Researchers have shown that cores form preferentially along dense

filaments (Lis et al., 2016). High angular resolution interferometric continuum studies give

insights into multiple systems.

Spectroscopy

Spectroscopy is the dispersion of an object's light into its component colours or energies. By

performing this analysis and dissection of an object's light astronomers can infer the physical

properties of that object, such as temperature, mass, luminosity and composition (Kulesa, C.,

1997). There are two distinctive classes of spectra, continuous and discrete. For continuous

spectra, the light is composed of a wide range of colours. With discrete spectra, a researcher sees

only bright or dark lines at very distinct and sharply defined colours. Discrete spectra with bright

lines are called emission spectra and those with dark lines are called absorption spectra.

Continuous spectra arise from dense gases or solid objects which radiate away their heat through

the production of light. Stars emit in a predominantly continuous spectrum. Discrete spectra are

the observable results of the physics of atoms (Kulesa, C., 1997). Emission line spectra are

concerned with the electron clouds surrounding the nuclei of atoms and can only have a very

specific energy dictated by quantum mechanics. Each element on the periodic table has its own

set of possible energy levels, which are distinct and identifiable. Atoms will tend to settle at the

lowest energy state, called the ground state. This mean an excited atom must dump some of it's

energy by way of emitting a wave of light at that exact energy. This energy dump corresponds to

a specific colour or wavelength and thus researchers see a bright line at that exact wavelength,

otherwise known as an emission spectrum (Kulesa, C., 1997). Tiny changes of energy in an atom

generate photons with small energies and long wavelengths, such as radio waves. Further, large

changes in energy in an atom will mean that high energy, shorter wavelength photons, such as

UV, x-ray or gamma rays are emitted. Absorption line spectra is the opposite process, with

atoms absorbing specific energetic photons that have become excited, jumping from the ground

state to a higher energy level. If a star with a continuous spectrum is shining upon an atom, the

wavelength corresponding to possible energy transition within that atom will be absorbed and

therefore a researcher will not see them, in this way - dark -line absorption spectrum is created

(Kulesa, C., 1997).

A spectrometer works when a telescope light beam enters the spectrometer. The focal point of

the telescope beam is brought to the slit of the spectrometer, with the slit being what is ultimately

imaged on the detector. The light passing through the slit is then reflected off a collimating

mirror, which parallelizes the beam of light before sending it off to the diffraction grating. This

optical element disperses the parallel beams of light into their component colours or wavelengths

(Kulesa, C., 1997). This creates an image of the slit that is spread out like a rainbow by colour.

The new colour dispersed bean of light is then focused and imaged on the detector by the camera

lens or a CCD array.

Figure 9: Spectra from two galaxies with star birth regions. Source:

http://loke.as.arizona.edu/~ckulesa/camp/spectroscopy_examples.html

Starburst galaxies are best studied in the infrared and radio regions of the spectrum, since star

forming galaxies often contain so much dust and gas visible light can't penetrate to the cores

where star formation activity is taking place (Kulesa, C., 1997). Above is an infrared spectrum of

two different star birth galaxies, imaged at 2.0 - 2.5 microns. Most of the features in the spectra

are from molecular hydrogen, H2, the stuff stars are made from. These molecular hydrogen

emission lines tell us that the molecular gas in the first galaxy is very hot in the top of the galaxy,

and is excited by shock heated gas. The bottom galaxy spectra is telling us it has molecular

hydrogen excited by UV light emitted from recently formed young, hot stars (Kulesa, C., 1997).

D) How have these surveys changed our understanding of star formation.

Each of these surveys has its own merits and shortcomings. Each survey was undertaken to

provide the astronomical research community with a wealth of data, mostly regarding our

galaxy, the Milky Way. By far the largest contribution to understanding star formation has come

from the ALMA instruments. Observing star formation is best accomplished by investigating the

infrared and radio wavelengths, whereby the GLIMPSE survey and the ATLASGAL surveys are

very useful for astronomers investigating star formation. The ALMA datasets provide for the

highest resolution information for astronomers to work with. They are able to penetrate the dust

and gas, while providing spectra for researchers to investigate at the cores of molecular clouds

where star formation is taking place. Current limitations to determining the physical processes

involved in star formation include: what triggers the cloud collapse, what the role of magnetic

fields are and what explains the masses of the new born stars. These surveys are able to probe

these questions while none of them answers all the questions fully. Our entire Milky Way

composed of approximately 100 billion stars appears to be evolving steadily, forming new stars

at a rate of approximately three solar masses per year (Dunlop, J., 2011). However, much

evidence exists to suggest that there was once a dark ages period in stellar formation, following

the big bang, when gas needed to cool to allow for the first molecular clouds to form. Observing

regions of star formation involves dissecting their spectra into stellar populations of measurable

mass, age and chemical compositions (Dunlop, J., 2011). However the further back in time a

researcher looks the less information they have to work with. We know that stars and galaxies

existed at redshifts of z = approximately 8.5, extending our cosmic star formation history to

within 500 million years of the big bang (Dunlop, J., 2011). These first galaxies and stars contain

very young stellar populations with stars of very low metallicity. Researchers are interested in

these first stellar birth regions as they help to further the field of our universe's cosmic star

formation history.

References:

Dionatos, O., & Güdel, M. (2016). The feedback of atomic jets from embedded protostars in

NGC 1333. arXiv preprint arXiv:1608.06131.

Dunlop, J. S. (2011). The Cosmic History of Star Formation. Science, 333(6039), 178-181.

Fischer, W. J., Padgett, D. L., Stapelfeldt, K. L., & Sewilo, M. (2016). A WISE Census of Young

Stellar Objects in Canis Major. arXiv preprint arXiv:1606.01896.

Flynn,Chris., 2005, Lecture 4B: Radiation case studies (HII regions)., Accesses November 5th,

2016.

Jørgensen, J. K., van der Wiel, M. H. D., Coutens, A., Lykke, J. M., Müller, H. S. P., van

Dishoeck, E. F., ... & Favre, C. (2016). The ALMA Protostellar Interferometric Line Survey

(PILS): First results from an unbiased submillimeter wavelength line survey of the Class 0

protostellar binary IRAS 16293-2422 with ALMA. arXiv preprint arXiv:1607.08733.

Kirk, H., Di Francesco, J., Johnstone, D., Duarte-Cabral, A., Sadavoy, S., Hatchell, J., ... &

Currie, M. J. (2016). The JCMT Gould Belt survey: a first look at dense cores in Orion B. The

Astrophysical Journal, 817(2), 167.

Lefloch, B., Vastel, C., Viti, S., Jimenez-Serra, I., Codella, C., Podio, L., ... & Bachiller, R.

(2016). Phosphorus-bearing molecules in solar-type star forming regions: First PO

detection. Monthly Notices of the Royal Astronomical Society, stw1918.

Lis, D. C., Wootten, H. A., Gerin, M., Pagani, L., Roueff, E., van der Tak, F. F., ... & Walmsley,

C. M. (2016). Star Formation and Feedback: A Molecular Outflow-Prestellar Core Interaction in

L1689N. arXiv preprint arXiv:1605.01239.

Louvet, F., Dougados, C., Cabrit, S., Hales, A., Pinte, C., Menard, F., ... & Gueth, F. (2016).

ALMA observations of the Th 28 protostellar disk-A new exemple of counter-rotation between

disk and optical jet. arXiv preprint arXiv:1607.08645.

Olmi, L., Cunningham, M., Elia, D., & Jones, P. (2016). The segregation of starless and

protostellar clumps in the Hi-GAL l= 224deg region. arXiv preprint arXiv:1608.05262.

Seifried, D., Sánchez-Monge, Á., Walch, S., & Banerjee, R. (2016). Revealing the dynamics of

Class 0 protostellar discs with ALMA. Monthly Notices of the Royal Astronomical

Society, 459(2), 1892-1906.

Shimonishi, T., Onaka, T., Kawamura, A., & Aikawa, Y. (2016). Detection of a hot molecular

core in the Large Magellanic Cloud with ALMA. arXiv preprint arXiv:1606.02823.

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