Star Formation in Cygnus X

Star Formation in Cygnus X
Author: Soumen Deb
Publisher:
Total Pages: 0
Release: 2022
Genre: Interstellar matter
ISBN:

In astrophysics, stellar evolution is one of the most discussed topics. Although a significant amount of research and advancement of instrumentation over the last few decades have contributed to this field greatly, our understanding of the pre-main sequence evolution remains largely incomplete. The general model for the formation of protostars within the ISM is the virial instability in cold molecular gas resulting in spontaneous gravitational collapse. However, the complete understanding of this instability requires a set of other physical factors, including the hydrodynamic turbulence in the ISM, local magnetic field strength, and feedback from surrounding high-mass stars, not all of them are well-understood. This work investigates the effect of stellar feedback on local star formation and the extent of energy support for molecular clouds provided by protostellar outflows within them. I first look into a specific case of potentially triggered star formation in Cygnus X, being one of the most active star-forming regions in the Milky Way. Using multi-line submillimetre emissions as well as radio continuum and infrared data, I measure the properties of two highly energetic molecular outflows near the massive stellar complex Cygnus OB2 complex. I show structure, physical conditions, and timescale of the outflows and the associated photoionized rim are consistent with a triggering scenario. I further investigate 13 such molecular outflows in Cygnus X and measure their properties using multi-line data which I find are similar to the previous surveys of outflows throughout the galaxy. Additionally, I develop and test a method to measure the same properties using single spectral line emission. This is useful in surveys where optically thin line data are not available. Next, I implement our method to estimate outflow properties in a large-scale survey of 82 outflows, many of which were previously unknown, based on single spectral-line observations. I use machine learning to fill out missing information on protostellar luminosity using existing catalogues and investigate the comparative predictive powers of line emission and radio continuum data on local outflow formation. Next, by comparing outflow power to turbulent dissipation power I show that single-generational outflows cannot provide enough energy support for the surrounding molecular clouds. Finally, I search for evidence of large-scale triggering of star formation and find that an ionization front can perhaps trigger local star formation where molecular gas emission is high, however, find no evidence for this effect to be strong.

Diffuse Molecular Gas in the Cygnus X Star Forming Region and Its Effect on the Star Formation Law

Diffuse Molecular Gas in the Cygnus X Star Forming Region and Its Effect on the Star Formation Law
Author: Kaylie Green
Publisher:
Total Pages: 157
Release: 2015
Genre: Gases
ISBN:

Observations of star forming regions in our Milky Way show that there are two different forms of molecular gas: bright star forming molecular clouds and large diffuse clouds. What is not yet known is the difference in physical properties between these two types of molecular gas and the contribution of these diffuse clouds to the star formation efficiency in our galaxy. In this thesis I identify physical properties of low surface brightness gas in the nearby star forming regions of Cygnus X and W80, and explore the presence of these diffuse clouds as solutions to the increased efficiency of star formation observed in local clouds. I find that these low surface brightness clouds do not contribute in a significant way to the total molecular gas mass of the region. I also find that the method used for tracing star formation has a larger effect on the calculation of large scale star formation rate than previously thought.

Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region

Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region
Author:
Publisher:
Total Pages: 13
Release: 2010
Genre:
ISBN:

We present observations of newly discovered 24 micron circumstellar structures detected with MIPS around three evolved stars in the Cygnus-X star-forming region. One of the objects, BD+43 3710, has a bipolar nebula, possibly due to an outflow or a torus of material. A second, HBHA 4202-22, a Wolf-Rayet candidate, shows a circular shell of 24 micron emission suggestive of either a limb-brightened shell or disk seen face-on. No diffuse emission was detected around either of these two objects in the Spitzer 3.6-8 micron IRAC bands. The third object is the luminous blue variable candidate G79.29+0.46. We resolved the previously known inner ring in all four IRAC bands. The 24 micron emission from the inner ring extends ~1 deg. 2 beyond the shorter wavelength emission, well beyond what can be attributed to the difference in resolutions between MIPS and IRAC. Additionally, we have discovered an outer ring of 24 micron emission, possibly due to an earlier episode of mass loss. For the two shell stars, we present the results of radiative transfer models, constraining the stellar and dust shell parameters. The shells are composed of amorphous carbon grains, plus polycyclic aromatic hydrocarbons in the case of G79.29+0.46. Both G79.29+0.46 and HBHA 4202-22 lie behind the main Cygnus-X cloud. Although G79.29+0.46 simply may be on the far side of the cloud, HBHA 4202-22 is unrelated to the Cygnus-X star formation region.

BLAST

BLAST
Author: Jorge Luis Morales Ortiz
Publisher:
Total Pages: 184
Release: 2009
Genre:
ISBN:

Handbook of Star Forming Regions: The northern sky

Handbook of Star Forming Regions: The northern sky
Author: Bo Reipurth
Publisher:
Total Pages: 0
Release: 2008
Genre: Northern sky (Astronomy)
ISBN: 9781583816707

The Handbook describes the 6̃0 most important star forming regions within approximately 2 kpc, and has been written by a team of 105 authors with expertise in the individual regions. It consists of two full-color volumes, one for the northern and one for the southern hemisphere, with a total of over 1900 pages. The Handbook is full of stunning color images from some of the best astrophotographers, complementing the extensive research, figures, and tables presented by the authors. These volumes aim to be a source of comprehensive factual information about each region, with extensive references to the literature. A useful reference guide for both researchers and students, the Handbook provides a unique and detailed presentation of our current knowledge about the nearest and most important star forming regions.

The Physics of Star Formation and Early Stellar Evolution

The Physics of Star Formation and Early Stellar Evolution
Author: Charles J. Lada
Publisher: Springer Science & Business Media
Total Pages: 779
Release: 2012-12-06
Genre: Science
ISBN: 9401136424

The origin of stars is one of the principle mysteries of nature. During the last two decades advances in technology have enabled more progress to be made in the quest to understand stellar origins than at any other time in history. The study of star formation has developed into one of the most important branches of mod ern astrophysical research. A large body of observational data and a considerable literat ure now exist concerning this topic and a 1arge community of international astronomers and physicists devote their efforts attempting to decipher the secrets of stellar birth. Yet, the young astronomerjphysicist or more advanced researcher desiring to obtain a basic background in this area of research must sift through a very diverse and sometimes bewildering literature. A literature which includes research in many discip1ines and sub discip1ines of classical astrophysics from stel lar structure to the interstellar medium and encompasses the entire range of the electromagnetic spectrum from radio to gamma rays. Often, the reward of a suc cessfu1 foray through the current literature is the realization that the results can be obsolete and outdated as soon as the ink is dry in the journal or the conference proceeding in which they are published.

Principles of Star Formation

Principles of Star Formation
Author: Peter Bodenheimer
Publisher: Springer Science & Business Media
Total Pages: 352
Release: 2011-07-10
Genre: Science
ISBN: 3642150632

Understanding star formation is one of the key fields in present-day astrophysics. This book treats a wide variety of the physical processes involved, as well as the main observational discoveries, with key points being discussed in detail. The current star formation in our galaxy is emphasized, because the most detailed observations are available for this case. The book presents a comparison of the various scenarios for star formation, discusses the basic physics underlying each one, and follows in detail the history of a star from its initial state in the interstellar gas to its becoming a condensed object in equilibrium. Both theoretical and observational evidence to support the validity of the general evolutionary path are presented, and methods for comparing the two are emphasized. The author is a recognized expert in calculations of the evolution of protostars, the structure and evolution of disks, and stellar evolution in general. This book will be of value to graduate students in astronomy and astrophysics as well as to active researchers in the field.

The Labyrinth of Star Formation

The Labyrinth of Star Formation
Author: Dimitris Stamatellos
Publisher: Springer Science & Business Media
Total Pages: 490
Release: 2014-04-03
Genre: Science
ISBN: 3319030418

This volume contains the proceedings from the conference "The Labyrinth of Star Formation" that was held in Crete, Greece, in June 2012, to honour the contributions to the study of star formation made by Professor Anthony Whitworth of Cardiff University. The book covers many aspects of theoretical and observational star formation: low-mass star formation; young circumstellar discs; computational methods; triggered star formation; the stellar initial mass function; high-mass star formation and stellar clusters. Each section starts with a review paper, followed by papers discussing recent theoretical and observational work. This volume summarises our current understanding of star formation and is useful for both graduate students and researchers alike.