1 Stellar Birth and Stellar Structure Reflection Nebula

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1 Stellar Birth and Stellar Structure Reflection Nebula

Stellar Birth and Stellar Structure Dense “cold” clouds in the Interstellar Medium, or the ISM 75% hydrogen 25% helium and trace amounts of : carbon, oxygen, nitrogen A clouds of gas and dust is called a nebula. • Dark nebula • Emission Nebula • Reflection Nebula This picture is a dark nebula. Is is called the “Horsehead”. Reflection Nebula The Pleiades cluster: the starlight scatters off the gas and especially the dust. Star cluster move through the ISM; as they do, a “hollow wake” can be carved out by the starlight from the very brightest stars. Reflection nebulae appear blue in color. Direction of motion Area of low density 1 Examples of Emission Nebulae Dark Nebula and Interstellar Reddening VISIBLE NEAR IR (VERY RED) The “Dark Cloud” blocks out starlight in the visible. However, observed in the very very red, the starlight does make it through the cold, dense, dusty cloud. Interstellar Reddening occurs because blue light scatters more efficiently than does red light. This is why reflection nebulae appear blue and sunsets appear red. 2 Formation of Stars From the Interstellar Medium The gravitationally unstable clumps become molecular clouds, which have molecules- required for cooling and contraction into stars. Note that the stars are in a cluster. Later, as they drift apart they are called an association. Examples of Stars Forming protostar 3 Stellar Birth and the Birth Line Bipolar outflow (jets) Accretion disk Herbig-Haro object The time it takes for a protostar to These protostars are in the bipolar outflow contract to a main-sequence star phase of their birth. Forming stars have depends upon mass. accretion disks that focus material and energize it into these Herbig-Haro objects. The larger the mass, the shorter the birthing process. 4 .

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Midterm Results the Milky Way in the Infrared
3/2/10 Lecture 13 : Midterm Results The Interstellar Medium and Cosmic Recycling A2020 Prof. Tom Megeath The Milk The Milky Way in the Infrared Way from Above (artist conception) The Milky Way appears to have a bar and four spiral arms. Star formation and hot blue stars concentrated in arms. View from the Earth: Edge On Infrared light penetrates the clouds and shows the entire galaxy 1 3/2/10 NGC 7331: the Milky Way’s Twins The Interstellar Medium The space between the stars is not empty, but ﬁlled with a very low density of matter in the form of: •Atomic hydrogen •Ionized hydrogen •Molecular Hydrogen •Cosmic Rays •Dust grains •Many other molecules (water, carbon monoxide, formaldehyde, methanol, etc) •Organic molecules like polycyclic aromatic hydrocarbons How do we know the gas is there? Review: Kirchoff Laws Remainder of the Lecture Foreground gas cooler, absorption 1. How we observe and study the interstellar medium 2. The multiwavelength Milky Way Absorbing gas hotter, 3. Cosmic Recycling emission lines (and (or cooler blackbody) blackbody) If foreground gas and emitting blackbody the same temperature: perfect blackbody (no lines) Picture from Nick Strobel’s astronomy notes: www.astronomynotes.com 2 3/2/10 Observing the ISM through Absorption Lines • We can determine the composition of interstellar gas from its absorption lines in the spectra of stars • 70% H, 28% He, 2% heavier elements in our region of Milky Way Picture from Nick Strobel’s astronomy notes: www.astronomynotes.com Emission Lines Emission Line Nebula M27 Emitted by atoms and ions in planetary and HII regions.
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Arxiv:1904.06897V1 [Astro-Ph.SR] 15 Apr 2019
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Gas and dust in the Magellanic clouds A Thesis Submitted for the Award of the Degree of Doctor of Philosophy in Physics To Mangalore University by Ananta Charan Pradhan Under the Supervision of Prof. Jayant Murthy Indian Institute of Astrophysics Bangalore - 560 034 India April 2011 Declaration of Authorship I hereby declare that the matter contained in this thesis is the result of the inves- tigations carried out by me at Indian Institute of Astrophysics, Bangalore, under the supervision of Professor Jayant Murthy. This work has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: ii Certiﬁcate This is to certify that the thesis entitled ‘Gas and Dust in the Magellanic clouds’ submitted to the Mangalore University by Mr. Ananta Charan Pradhan for the award of the degree of Doctor of Philosophy in the faculty of Science, is based on the results of the investigations carried out by him under my supervi- sion and guidance, at Indian Institute of Astrophysics. This thesis has not been submitted for the award of any degree, diploma, associateship, fellowship, etc. of any university or institute. Signed: Date: iii Dedicated to my parents ========================================= Sri. Pandab Pradhan and Smt. Kanak Pradhan ========================================= Acknowledgements It has been a pleasure to work under Prof. Jayant Murthy. I am grateful to him for giving me full freedom in research and for his guidance and attention throughout my doctoral work inspite of his hectic schedules. I am indebted to him for his patience in countless reviews and for his contribution of time and energy as my guide in this project.
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Optical and UV Surface Brightness of Translucent Dark Nebulae ? Dust Albedo, Radiation field, and fluorescence Emission by H2 K
A&A 617, A42 (2018) https://doi.org/10.1051/0004-6361/201833196 Astronomy & © ESO 2018 Astrophysics Optical and UV surface brightness of translucent dark nebulae ? Dust albedo, radiation field, and fluorescence emission by H2 K. Mattila1, M. Haas2, L. K. Haikala3, Y-S. Jo4, K. Lehtinen1,8, Ch. Leinert5, and P. Väisänen6,7 1 Department of Physics, University of Helsinki, PO Box 64, 00014 Helsinki, Finland e-mail: [email protected] 2 Astronomisches Institut, Ruhr-Universität Bochum, Universitätsstrasse 150, 44801 Bochum, Germany 3 Instituto de Astronomía y Ciencias Planetarias de Atacama, Universidad de Atacama, Copayapu 485, Copiapo, Chile 4 Korea Astronomy and Space Science Institute (KASI), 776 Daedeokdae-ro, Yuseong-gu, Daejeon 305-348, Korea 5 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany 6 South African Astronomical Observatory, PO Box 9 Observatory, Cape Town, South Africa 7 Southern African Large Telescope, PO Box 9 Observatory, Cape Town, South Africa 8 Finnish Geospatial Research Institute FGI, Geodeetinrinne 2, 02430 Masala, Finland Received 9 April 2018 / Accepted 27 May 2018 ABSTRACT Context. Dark nebulae display a surface brightness because dust grains scatter light of the general interstellar radiation field (ISRF). High-galactic-latitudes dark nebulae are seen as bright nebulae when surrounded by transparent areas which have less scattered light from the general galactic dust layer. Aims. Photometry of the bright dark nebulae LDN 1780, LDN 1642, and LBN 406 shall be used to derive scattering properties of dust and to investigate the presence of UV fluorescence emission by molecular hydrogen and the extended red emission (ERE).
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E. E. Barnard and His Dark Nebula!
Visible throughout our galaxy are clouds of interstellar matter, thin but widespread wisps of gas and dust. Some of the stars near nebulae are often very massive and their high-energy radiation can excite the gas of the nebula to shine; such nebula is called emission nebula. If the stars are dimmer or further away, their light is reflected by the dust in the nebula and can be seen as reflection nebula. Some nebulae are only visible by the absorption of the light from objects behind them. These are called dark nebula Edward Emerson Barnard was a professor of astronomy at the University of Chicago Yerkes Observatory. As a pioneer in astrophotography, he cataloged a series of dark nebula of the Milky Way. Through this work of studying the structure of the Milky Way, Barnard discovered that certain dark regions of our galaxy are actually clouds of gas and dust that obscured the more distant stars in the background. Today, we’re going to look-back on his life and accomplishments. We’ll also review several of my observations of his dark nebula. Barnard’s Early Years: A: Childhood, Work, and Stargazing Edward Emerson Barnard was born on December 16th, 1857 in Nashville Tennessee, at the cusp of the Civil War. His mother, Elizabeth, (at the age of 42), had moved the family from Cincinnati to Nashville a few months prior to Edward’s birth, when his father, Reuben Barnard had passed away. The family lived in near poverty, with Elizabeth as the sole provider working several small jobs, the most profitable being that of her making wax flowers, which she had a skill at creating.
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'This Is Not a Pipe': Curious Dark Nebula Seen As Never Before 15 August 2012
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