Lecture 8 Overshoot Mixing, Semiconvection, Mass Loss, and Rotation
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Star Formation and Mass Assembly in High Redshift Galaxies
A&A 504, 751–767 (2009) Astronomy DOI: 10.1051/0004-6361/200811434 & c ESO 2009 Astrophysics Star formation and mass assembly in high redshift galaxies P. Santini1,2,A.Fontana1, A. Grazian1,S.Salimbeni1,3, F. Fiore1, F. Fontanot4, K. Boutsia1, M. Castellano1,2, S. Cristiani5, C. De Santis6,7, S. Gallozzi1, E. Giallongo1, N. Menci1, M. Nonino5, D. Paris1, L. Pentericci1, and E. Vanzella5 1 INAF – Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio (RM), Italy e-mail: [email protected] 2 Dipartimento di Fisica, Università di Roma “La Sapienza”, P.le A. Moro 2, 00185 Roma, Italy 3 Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003, USA 4 MPIA Max-Planck-Institute für Astronomie, Koenigstuhl 17, 69117 Heidelberg, Germany 5 INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131 Trieste, Italy 6 Dip. di Fisica, Università Tor Vergata, via della Ricerca Scientifica 1, 00133 Roma, Italy 7 INFN – Roma Tor Vergata, via della Ricerca Scientifica 1, 00133 Roma, Italy Received 27 November 2008 / Accepted 24 April 2009 ABSTRACT Aims. The goal of this work is to infer the star formation properties and the mass assembly process of high redshift (0.3 ≤ z < 2.5) galaxies from their IR emission using the 24 μm band of MIPS-Spitzer. Methods. We used an updated version of the GOODS-MUSIC catalog, which has multiwavelength coverage from 0.3 to 24 μmand either spectroscopic or accurate photometric redshifts. We describe how the catalog has been extended by the addition of mid-IR fluxes derived from the MIPS 24 μm image. -
Luminous Blue Variables
Review Luminous Blue Variables Kerstin Weis 1* and Dominik J. Bomans 1,2,3 1 Astronomical Institute, Faculty for Physics and Astronomy, Ruhr University Bochum, 44801 Bochum, Germany 2 Department Plasmas with Complex Interactions, Ruhr University Bochum, 44801 Bochum, Germany 3 Ruhr Astroparticle and Plasma Physics (RAPP) Center, 44801 Bochum, Germany Received: 29 October 2019; Accepted: 18 February 2020; Published: 29 February 2020 Abstract: Luminous Blue Variables are massive evolved stars, here we introduce this outstanding class of objects. Described are the specific characteristics, the evolutionary state and what they are connected to other phases and types of massive stars. Our current knowledge of LBVs is limited by the fact that in comparison to other stellar classes and phases only a few “true” LBVs are known. This results from the lack of a unique, fast and always reliable identification scheme for LBVs. It literally takes time to get a true classification of a LBV. In addition the short duration of the LBV phase makes it even harder to catch and identify a star as LBV. We summarize here what is known so far, give an overview of the LBV population and the list of LBV host galaxies. LBV are clearly an important and still not fully understood phase in the live of (very) massive stars, especially due to the large and time variable mass loss during the LBV phase. We like to emphasize again the problem how to clearly identify LBV and that there are more than just one type of LBVs: The giant eruption LBVs or h Car analogs and the S Dor cycle LBVs. -
SHELL BURNING STARS: Red Giants and Red Supergiants
SHELL BURNING STARS: Red Giants and Red Supergiants There is a large variety of stellar models which have a distinct core – envelope structure. While any main sequence star, or any white dwarf, may be well approximated with a single polytropic model, the stars with the core – envelope structure may be approximated with a composite polytrope: one for the core, another for the envelope, with a very large difference in the “K” constants between the two. This is a consequence of a very large difference in the specific entropies between the core and the envelope. The original reason for the difference is due to a jump in chemical composition. For example, the core may have no hydrogen, and mostly helium, while the envelope may be hydrogen rich. As a result, there is a nuclear burning shell at the bottom of the envelope; hydrogen burning shell in our example. The heat generated in the shell is diffusing out with radiation, and keeps the entropy very high throughout the envelope. The core – envelope structure is most pronounced when the core is degenerate, and its specific entropy near zero. It is supported against its own gravity with the non-thermal pressure of degenerate electron gas, while all stellar luminosity, and all entropy for the envelope, are provided by the shell source. A common property of stars with well developed core – envelope structure is not only a very large jump in specific entropy but also a very large difference in pressure between the center, Pc, the shell, Psh, and the photosphere, Pph. Of course, the two characteristics are closely related to each other. -
1 Firm and Less Firm Outcomes of Stellar Evolution Theory
i i Laura Greggio and Alvio Renzini: Stellar Populations — Chap. renzini9181c01 — 2011/7/12 — page 1 — le-tex i i 1 1 Firm and Less Firm Outcomes of Stellar Evolution Theory Stellar evolution theory is a mature science which provides the backbone to the theory of stellar populations and the construction of their synthetic luminosities, colors and spectra. In turn, synthetic stellar populations offer the virtually unique possibility to estimate the ages of stellar systems from star clusters to whole galax- ies, their star formation rates and star formation histories, and their mass in stars. This chapter is no substitute to a whole textbook on stellar evolution, of which there are many. It rather offers an introduction to stellar evolution, meant to familiarize the reader with the pertinent nomenclature and a few key concepts. Particular at- tention is devoted to highlight the strengths and weaknesses of current methods, assumptions and results of stellar evolution theory, in particular concerning their impact on synthetic stellar populations. Further readings on the treated issues are listed at the end of this chapter. 1.1 A Brief Journey through Stellar Evolution 1.1.1 A9Mˇ Star Figure 1.1 shows the calculated evolutionary path on the Hertzsprung–Russell di- agram (HRD) of a 9 Mˇ star of solar composition. Letters mark critical points in thecourseofevolutionandTable1.1givesthe corresponding times to reach them. Specifically, the various points mark the following events: A: Beginning of steady hydrogen burning, zero age main sequence (ZAMS). C-C0: Exhaustion of hydrogen in the core, and ignition of hydrogen burning in a shell surrounding the hydrogen-exhausted core. -
Pop III Binary Population Synthesis
Remnants of first stars for gravitational wave sources Tomoya Kinugawa Institute for Cosmic Ray Research The University of Tokyo collaborators: T. Nakamura, K. Inayoshi, K. Hotokezaka, D. Nakauchi A. Miyamoto, N. Kanda, A. Tanikawa, T. Yoshida The beginning of Gravitational wave astronomy • Gravitational wave detectors KAGRA Advanced LIGO Advanced VIRGO ©VIRGO ©KAGRA ©LIGO Masses of GW events • GW events show that there are many massive BHs (≳30 Msun). • 7/10 BBHs are massive BBHs • On the other hand, the typical mass of BHs in X-ray binaries is ~10 Msun. The LIGO scientific collaboration 2018 Origin of massive BBHs 7/10 GW BBHs are massive BBHs In order to explain the origin of such massive BBHs Many theories exist such as • 1)Pop II BBH • 2)Pop III BBH No metal field binaries • 3)Primordial Binary BH • 4)N body origin from Globular Cluster • ……………………. Pop III binary population synthesis We simulate 106 Pop III-binary evolutions and estimate how many binaries become compact binary which merges within Hubble time. ×84 models (Kinugawa et al.2014, 2016) Initial stellar parameters are decided by Monte Carlo method with initial distribution functions • Initial parameter (M1,M2,a,e) distribution in our standard model M1 : Flat (10 M<M<100 M) q=M2/M1 : P(q)=const. (0<q<1) The same distribution functions 6 adopted for Pop I population a : P(a)∝1/a (amin<a<10 R) synthesis e : P(e)∝e (0<e<1) • de Souza SFR Total mass distribution of BBH which merge within the Hubble time Typical total mass M~60 M Z=0 (Pop III) (30 M +30 M) TK et al. -
Chapter 16 the Sun and Stars
Chapter 16 The Sun and Stars Stargazing is an awe-inspiring way to enjoy the night sky, but humans can learn only so much about stars from our position on Earth. The Hubble Space Telescope is a school-bus-size telescope that orbits Earth every 97 minutes at an altitude of 353 miles and a speed of about 17,500 miles per hour. The Hubble Space Telescope (HST) transmits images and data from space to computers on Earth. In fact, HST sends enough data back to Earth each week to fill 3,600 feet of books on a shelf. Scientists store the data on special disks. In January 2006, HST captured images of the Orion Nebula, a huge area where stars are being formed. HST’s detailed images revealed over 3,000 stars that were never seen before. Information from the Hubble will help scientists understand more about how stars form. In this chapter, you will learn all about the star of our solar system, the sun, and about the characteristics of other stars. 1. Why do stars shine? 2. What kinds of stars are there? 3. How are stars formed, and do any other stars have planets? 16.1 The Sun and the Stars What are stars? Where did they come from? How long do they last? During most of the star - an enormous hot ball of gas day, we see only one star, the sun, which is 150 million kilometers away. On a clear held together by gravity which night, about 6,000 stars can be seen without a telescope. -
The Great Supernova of 1987
The great supernova of 1987 SN 1987 A. Despite their apparently very different objectives, astrophy sics - the study of the largest structures in the Universe - and particle physics - the study of the smallest - have always had common ground. On 23 February 1987 a super nova explosion provided addi tional impetus to reinforce these links. In this article, David Schramm of the Univer sity of Chicago and the NASA/Fermilab Astrophysics Center, explains why. One of the most spectacular events in modern astrophysics occurred on 23 February 1987, when light and neutrinos from a supernova ex plosion in the Large Magellanic Cloud (LMC) first reached Earth. The LMC (a satellite of our Milky Way Galaxy) is 170,000 light years away, making the event, code- named SN 1987A, the closest vi sual supernova since Kepler ob served one almost 400 years ago. Most of our knowledge of super- novae has come either from obser vations of outbursts in distant gal axies, too far away to obtain neu trinos, or from studies of old rem nants in our Galaxy, thus missing the fireworks. Having a supernova blast off re also proved that our ideas about novae that were missed in previous latively nearby while neutrino and element formation in exploding supernova rate estimates. Another electromagnetic radiation detectors stars were basically correct. In par exciting ingredient was the recent were in action has been fantastic. ticular, the gamma rays from ra report of a 0.5 ms pulsar remnant In addition, the pre-supernova star dioactive cobalt-56 indicated that in the supernova. -
Urania Nr 5/2001
Eta Carinae To zdjęcie mgławicy otaczającej gwiazdę // Carinae uzyskano za po mocą telskopu kosmicznego Hubble a (K. Davidson i J. Mors). Porównując je z innymi zdjęciami, a w szczególności z obrazem wyko nanym 17 miesięcy wcześniej, Auto rzy stwierdzili rozprężanie się mgła wicy z szybkością ok. 2,5 min km/h, co prowadzi do wniosku, że rozpo częła ona swe istnienie około 150 lat temu. To bardzo ciekawy i intrygujący wynik. Otóż największy znany roz błysk )j Carinae miał miejsce w roku 1840. Wtedy gwiazda ta stała się naj jaśniejszą gwiazdą południowego nie ba i jasność jej przez krótki czas znacznie przewyższała blask gwiaz dy Canopus. Jednak pyłowy dysk ob serwowany wokół)/ Carinae wydaje się być znacznie młodszy - jego wiek (ekspansji) jest oceniany na 100 lat, co może znaczyć, że powstał w cza sie innego, mniejszego wybuchu ob serwowanego w roku 1890. Więcej na temat tego intrygują cego obiektu przeczytać można we wnątrz numeru, w artykule poświę conym tej gwieździe. NGC 6537 Obserwacje przeprowadzone teleskopem Hubble’a pokazały istnienie wielkich falowych struktur w mgławicy Czerwonego Pająka (NGC 6537) w gwiazdozbiorze Strzelca.Ta gorąca i „wietrzna” mgławica powstała wokół jednej z najgorętszych gwiazd Wszech świata, której wiatr gwiazdowy wiejący z prędkością 2000-4500 kilometrów na sekundę wytwarza fale o wysokości 100 miliardów kilometrów. Sama mgławica rozszerza się z szybkością 300 km/s. Jest też ona wyjątkowo gorąca — ok. 10000 K. Sama gwiazda, która utworzyła mgławicę, jest obecnie białym karłem i musi mieć temperaturę nie niższą niż pół miliona stopni — jest tak gorąca, że nie widać jej w obszarach uzyskanych teleskopem Hubble’a, a świeci głównie w promieniowaniu X. -
Information Bulletin on Variable Stars
COMMISSIONS AND OF THE I A U INFORMATION BULLETIN ON VARIABLE STARS Nos November July EDITORS L SZABADOS K OLAH TECHNICAL EDITOR A HOLL TYPESETTING K ORI ADMINISTRATION Zs KOVARI EDITORIAL BOARD L A BALONA M BREGER E BUDDING M deGROOT E GUINAN D S HALL P HARMANEC M JERZYKIEWICZ K C LEUNG M RODONO N N SAMUS J SMAK C STERKEN Chair H BUDAPEST XI I Box HUNGARY URL httpwwwkonkolyhuIBVSIBVShtml HU ISSN COPYRIGHT NOTICE IBVS is published on b ehalf of the th and nd Commissions of the IAU by the Konkoly Observatory Budap est Hungary Individual issues could b e downloaded for scientic and educational purp oses free of charge Bibliographic information of the recent issues could b e entered to indexing sys tems No IBVS issues may b e stored in a public retrieval system in any form or by any means electronic or otherwise without the prior written p ermission of the publishers Prior written p ermission of the publishers is required for entering IBVS issues to an electronic indexing or bibliographic system to o CONTENTS C STERKEN A JONES B VOS I ZEGELAAR AM van GENDEREN M de GROOT On the Cyclicity of the S Dor Phases in AG Carinae ::::::::::::::::::::::::::::::::::::::::::::::::::: : J BOROVICKA L SAROUNOVA The Period and Lightcurve of NSV ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::: W LILLER AF JONES A New Very Long Period Variable Star in Norma ::::::::::::::::::::::::::::::::::::::::::::::::::: :::::::::::::::: EA KARITSKAYA VP GORANSKIJ Unusual Fading of V Cygni Cyg X in Early November ::::::::::::::::::::::::::::::::::::::: -
Spica the Blue Giant Spica Is on the Left, Venus Is the Brightest on the Bottom, with Jupiter Above
Spica the blue giant Spica is on the left, Venus is the brightest on the bottom, with Jupiter above. The constellation Virgo Spica is the brightest star in this constellation. It is the 15th brightest star in the sky and is located 260 light years from earth, which makes it one of the nearest stars to our sun. Many people throughout history have observed it including Copernicus and Hipparchus. Facts • Spica is a binary star system with the primary star at 10x the sun’s mass and 7x the sun’s radius. It puts out 12,100x the lumens as our sun, placing it in the luminosity range of a sub-giant to giant star. The magnitude reading is +1.04 with a temperature of 22,400 Kelvin. It is a flushed white helium type star. The companion is 7x the sun’s mass and has a radius 3.6x as large. The companion is main sequence. The distance between these two stars is 11 million miles. 80% of the light emitted from this area comes from Spica. Spica is also a strong source of x-rays. Spica is a binary system • There are up to 3 other components in this star system. The orbit around the barycenter, or common center of mass, is as quick as four days. The bodies are so close we cannot see them apart with our telescopes. We know this because of observations of the Doppler shift in the absorption lines of the spectra. The rotation rate of both stars is faster than their mutual orbital period. -
Types of Stars Notes
STARS QUESTION • When you think of a star, what comes to mind? WHAT IS A STAR? • Star- a fixed luminous point in the night sky that is a large, remote incandescent body. • Stars are a big ball of gas. • It is held together by its own gravity. • They are made mostly of hydrogen and helium. • The closest star to Earth is the Sun. HOW ARE STARS MADE? • Stars are born in nebulas, which are like star nurseries. • In a nebula, gravity forces gas together. • As the gas comes together, it heats up and the hydrogen in the gas starts to speed up. • Eventually, the gases form a dense, hot core. • The core is middle of the star and it provides the fuel for the star’s entire life. ARE ALL STARS THE SAME? • Just like people, stars come in different sizes and colors. • The main types of stars are: • Dwarf • Main Sequence • Giant • Super Giant • Dwarf Star- a very small stars with small mass. • The most common type of star in the DWARF STARS universe. • They burn very slowly • They live for a very long time. • Some can life for trillions of years before they run out of fuel. • They also don’t shine brightly. • Example- Proxima Centauri • Two Types: • White Dwarf • One of the hottest stars in the universe. • Red Dwarf • The coldest stars in the universe. MAIN SEQUENCE STARS • Also known as medium stars. • Our sun is a main sequence star. • They are usually yellow in color. • They have a medium temperature. • These stars typically live for about 10 billion years. -
Star Classification Stars Are Classified by Their Spectra (The Elements That They Absorb) and Their Temperature
Star Classification Stars are classified by their spectra (the elements that they absorb) and their temperature. There are seven main types of stars. In order of decreasing temperature, O, B, A, F, G, K, and M. O and B stars are uncommon but very bright; M stars are common but dim.. An easy mnemonic for remembering these is: "Oh be a fine girl, kiss me." Hertzsprung - Russell Diagram The Hertzsprung -Russell (H-R) Diagram is a graph that plots stars color (spectral type or surface temperature) vs. its luminosity (intrinsic brightness or absolutemagnitude). On it, astronomers plot stars' color, temperature, luminosity, spectral type, and evolutionary stage. This diagram shows that there are 3 very different types of stars: Most stars, including the sun, are "main sequence stars," fueled by nuclear fusion converting hydrogen into helium. For these stars, the hotter they are, the brighter. These stars are in the most stable part of their existence; this stage generally lasts for about 5 billion years. As stars begin to die, they become giants and supergiants (above the main sequence). These stars have depleted their hydrogen supply and are very old. The core contracts as the outer layers expand. These stars will eventually explode (becoming a planetary nebula or supernova, depending on their mass) and then become white dwarfs, neutron stars, or black holes (again depending on their mass). Smaller stars (like our Sun) eventually become faint white dwarfs (hot, white, dim stars) that are below the main sequence. These hot, shrinking stars have depleted their nuclear fuels and will eventually become cold, dark, black dwarfs.