Starview Visible Object Listing For: March 15, 2017 Local Time
Total Page：16
File Type：pdf, Size：1020Kb
Load more
Recommended publications
-
Winter Constellations
Winter Constellations *Orion *Canis Major *Monoceros *Canis Minor *Gemini *Auriga *Taurus *Eradinus *Lepus *Monoceros *Cancer *Lynx *Ursa Major *Ursa Minor *Draco *Camelopardalis *Cassiopeia *Cepheus *Andromeda *Perseus *Lacerta *Pegasus *Triangulum *Aries *Pisces *Cetus *Leo (rising) *Hydra (rising) *Canes Venatici (rising) Orion--Myth: Orion, the great hunter. In one myth, Orion boasted he would kill all the wild animals on the earth. But, the earth goddess Gaia, who was the protector of all animals, produced a gigantic scorpion, whose body was so heavily encased that Orion was unable to pierce through the armour, and was himself stung to death. His companion Artemis was greatly saddened and arranged for Orion to be immortalised among the stars. Scorpius, the scorpion, was placed on the opposite side of the sky so that Orion would never be hurt by it again. To this day, Orion is never seen in the sky at the same time as Scorpius. DSO’s ● ***M42 “Orion Nebula” (Neb) with Trapezium A stellar nursery where new stars are being born, perhaps a thousand stars. These are immense clouds of interstellar gas and dust collapse inward to form stars, mainly of ionized hydrogen which gives off the red glow so dominant, and also ionized greenish oxygen gas. The youngest stars may be less than 300,000 years old, even as young as 10,000 years old (compared to the Sun, 4.6 billion years old). 1300 ly. 1 ● *M43--(Neb) “De Marin’s Nebula” The star-forming “comma-shaped” region connected to the Orion Nebula. ● *M78--(Neb) Hard to see. A star-forming region connected to the Orion Nebula. -
• Classifying Stars: HR Diagram • Luminosity, Radius, and Temperature • “Vogt-Russell” Theorem • Main Sequence • Evolution on the HR Diagram
Stars • Classifying stars: HR diagram • Luminosity, radius, and temperature • “Vogt-Russell” theorem • Main sequence • Evolution on the HR diagram Classifying stars • We now have two properties of stars that we can measure: – Luminosity – Color/surface temperature • Using these two characteristics has proved extraordinarily effective in understanding the properties of stars – the Hertzsprung- Russell (HR) diagram If we plot lots of stars on the HR diagram, they fall into groups These groups indicate types of stars, or stages in the evolution of stars Luminosity classes • Class Ia,b : Supergiant • Class II: Bright giant • Class III: Giant • Class IV: Sub-giant • Class V: Dwarf The Sun is a G2 V star Luminosity versus radius and temperature A B R = R R = 2 RSun Sun T = T T = TSun Sun Which star is more luminous? Luminosity versus radius and temperature A B R = R R = 2 RSun Sun T = T T = TSun Sun • Each cm2 of each surface emits the same amount of radiation. • The larger stars emits more radiation because it has a larger surface. It emits 4 times as much radiation. Luminosity versus radius and temperature A1 B R = RSun R = RSun T = TSun T = 2TSun Which star is more luminous? The hotter star is more luminous. Luminosity varies as T4 (Stefan-Boltzmann Law) Luminosity Law 2 4 LA = RATA 2 4 LB RBTB 1 2 If star A is 2 times as hot as star B, and the same radius, then it will be 24 = 16 times as luminous. From a star's luminosity and temperature, we can calculate the radius. -
ASTR 545 Module 2 HR Diagram 08.1.1 Spectral Classes: (A) Write out the Spectral Classes from Hottest to Coolest Stars. Broadly
ASTR 545 Module 2 HR Diagram 08.1.1 Spectral Classes: (a) Write out the spectral classes from hottest to coolest stars. Broadly speaking, what are the primary spectral features that define each class? (b) What four macroscopic properties in a stellar atmosphere predominantly govern the relative strengths of features? (c) Briefly provide a qualitative description of the physical interdependence of these quantities (hint, don’t forget about free electrons from ionized atoms). 08.1.3 Luminosity Classes: (a) For an A star, write the spectral+luminosity class for supergiant, bright giant, giant, subgiant, and main sequence star. From the HR diagram, obtain approximate luminosities for each of these A stars. (b) Compute the radius and surface gravity, log g, of each luminosity class assuming M = 3M⊙. (c) Qualitative describe how the Balmer hydrogen lines change in strength and shape with luminosity class in these A stars as a function of surface gravity. 10.1.2 Spectral Classes and Luminosity Classes: (a,b,c,d) (a) What is the single most important physical macroscopic parameter that defines the Spectral Class of a star? Write out the common Spectral Classes of stars in order of increasing value of this parameter. For one of your Spectral Classes, include the subclass (0-9). (b) Broadly speaking, what are the primary spectral features that define each Spectral Class (you are encouraged to make a small table). How/Why (physically) do each of these depend (change with) the primary macroscopic physical parameter? (c) For an A type star, write the Spectral + Luminosity Class notation for supergiant, bright giant, giant, subgiant, main sequence star, and White Dwarf. -
Ptrsa, 365, 1307, 2007
Phil. Trans. R. Soc. A (2007) 365, 1307–1313 doi:10.1098/rsta.2006.1998 Published online 9 February 2007 Giant flares in soft g-ray repeaters and short GRBs BY S. ZANE* Mullard Space Science Laboratory, University College of London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK Soft gamma-ray repeaters (SGRs) are a peculiar family of bursting neutron stars that, occasionally, have been observed to emit extremely energetic giant flares (GFs), with energy release up to approximately 1047 erg sK1. These are exceptional and rare events. It has been recently proposed that GFs, if emitted by extragalactic SGRs, may appear at Earth as short gamma-ray bursts. Here, I will discuss the properties of the GFs observed in SGRs, with particular emphasis on the spectacular event registered from SGR 1806-20 in December 2004. I will review the current scenario for the production of the flare, within the magnetar model, and the observational implications. Keywords: soft gamma-ray repeaters; short gamma-ray bursts; stars: neutron 1. Introduction Soft gamma-ray repeaters (SGRs) are a small group (four known sources and one candidate) of neutron stars (NSs) discovered as bursting gamma-ray sources. During the quiescent state (i.e. outside bursts events), these sources are detected as persistent emitters in the soft X-ray range (less than 10 keV), with a luminosity of approximately 1035 erg sK1 and with a typical blackbody plus power law spectrum. Their NS nature is probed by the detection of periodic X-ray pulsations at a few seconds in three cases. Very recently, a hard and pulsed emission (20–100 keV) has been discovered in two sources (Mereghetti et al. -
Lithium Abundances in Fast Rotating Bright Giant Stars
Stellar Rotation Proceedings [AU Symposium No. 215, © 2003 [AU Andre Maeder & Philippe Eenens, eds. Lithium Abundances in Fast Rotating Bright Giant Stars J.D.Jr do NascimentoI, A. Lebre", R. Konstantinova-Antova' and J. R. De Medeiros! I-Departamento de Fisico Teorica e Experimental, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, R.N., Brazil; 2-GRAAL, UMR 5024 ISTEEM/CNRS, CC 072, Uniuersiie Montpellier II, F-34095 Montpellier Cedex, France; 3 Institute of Astronomy, 72 Tsarigradsko shose, BG-1784 Sofia, Bulgaria Abstract. We present the results of high resolution spectroscopic observations of Li I resonance doublet at A6707.8 A for fast rotating single stars of luminosity class II and lb. We present a discussion on the link between rotation and Li content in intermediate mass giant stars, with emphasis on their evolutionary status. At least one of the observed stars, HD 232862, a G8I1 with an unusual vsini of 20 km/s, present a Li-rich behavior. 1. The Problem and Observations This work brings the first results of a large observational campaign to deter- mine Li, rotation and CNO abundances for a sample of single bright giants and Ib supergiants, along the spectral region F, G and K. Measurements of Li and CNO surface content of evolved stars is of paramount importance to test quan- titative and qualitative theoretical predictions of the effects of nucleosynthesis and subsequent mixing events on the stellar surface abundances. A survey of bright giants and Ib supergiants along the spectral region F, G and K, has been carried out to study the possible link between the rotational be- havior and CNO abundances (do Nascimento & De Medeiros 2003). -
15.2 Patterns Among Stars
15.2 Patterns Among Stars Our goals for learning: What is a Hertzsprung-Russell diagram? What is the significance of the main sequence? What are giants, supergiants, and white dwarfs? Why do the properties of some stars vary? What is a Hertzsprung- Russell diagram? An H-R diagram plots the luminosity and temperature of stars. Luminosity Temperature Most stars fall somewhere on the main sequence of the H-R diagram. Stars with lower T and higher L than main- sequence stars must have larger radii. These stars are called giants and supergiants. Stars with higher T and lower L than main- sequence stars must have smaller radii. These stars are called white dwarfs. Stellar Luminosity Classes A star's full classification includes spectral type (line identities) and luminosity class (line shapes, related to the size of the star): I - supergiant II - bright giant III - giant IV - subgiant V - main sequence Examples: Sun - G2 V Sirius - A1 V Proxima Centauri - M5.5 V Betelgeuse - M2 I H-R diagram depicts: Temperature Color Spectral type Luminosity Luminosity Radius Temperature Which star is the hottest? Luminosity Temperature Which star is the hottest? A Luminosity Temperature Which star is the most luminous? Luminosity Temperature Which star is the most luminous? C Luminosity Temperature Which star is a main- sequence star? Luminosity Temperature Which star is a main- sequence star? D Luminosity Temperature Which star has the largest radius? Luminosity Temperature Which star has the largest radius? Luminosity C Temperature What is the significance of the main sequence? Main-sequence stars are fusing hydrogen into helium in their cores like the Sun. -
The History of Star Formation in Galaxies
Astro2010 Science White Paper: The Galactic Neighborhood (GAN) The History of Star Formation in Galaxies Thomas M. Brown ([email protected]) and Marc Postman ([email protected]) Space Telescope Science Institute Daniela Calzetti ([email protected]) Dept. of Astronomy, University of Massachusetts 24 25 26 I 27 28 29 30 0.5 1.0 1.5 V-I Brown et al. The History of Star Formation in Galaxies Abstract If we are to develop a comprehensive and predictive theory of galaxy formation and evolution, it is essential that we obtain an accurate assessment of how and when galaxies assemble their stel- lar populations, and how this assembly varies with environment. There is strong observational support for the hierarchical assembly of galaxies, but by definition the dwarf galaxies we see to- day are not the same as the dwarf galaxies and proto-galaxies that were disrupted during the as- sembly. Our only insight into those disrupted building blocks comes from sifting through the re- solved field populations of the surviving giant galaxies to reconstruct the star formation history, chemical evolution, and kinematics of their various structures. To obtain the detailed distribution of stellar ages and metallicities over the entire life of a galaxy, one needs multi-band photometry reaching solar-luminosity main sequence stars. The Hubble Space Telescope can obtain such data in the outskirts of Local Group galaxies. To perform these essential studies for a fair sample of the Local Universe will require observational capabilities that allow us to extend the study of resolved stellar populations to much larger galaxy samples that span the full range of galaxy morphologies, while also enabling the study of the more crowded regions of relatively nearby galaxies. -
Race to the Moons
Race to the Moons The year is 2169 and mankind has pretty much filled up the Earth. It has been 200 years since man first set foot on the Moon. Now there are cities on the Moon and Mars, and mining communities in the asteroid belt. But our Solar System is just the beginning. It might be home, but Earth is the only truly hospitable planet nearby. However, recent breakthroughs in warp travel mean that interstellar voyages are finally a reality. There are several extrasolar systems that have been discovered to have planets and moons which appear to be very Earthlike, and likely hospitable. The nearest of these is in the Gamma Leporis tri-star system, 29 light years away from Earth. A series of moons orbiting a gas giant named Yutu show breathable atmospheres, tolerable radiation levels, reasonable temperatures, liquid water, and plenty of land. Now, the race is on. Terran, Lunar, Martian, and Belter organizations are competing to be the first to send humans to one of these habitable moons and establish a permanent human colony. It will take research, determination, and a bit of luck to be the first to arrive. Do you have what it takes to drive the next great space triumph and win the Race to the Moons? Overview: Race to the Moons is a worker placement game where 2-5 players (solo variant included) are working to research the technology needed to complete an interstellar mission and be the first to found a human colony on a moon system around a gas planet in another solar system. -
Spectroscopy of Variable Stars
Spectroscopy of Variable Stars Steve B. Howell and Travis A. Rector The National Optical Astronomy Observatory 950 N. Cherry Ave. Tucson, AZ 85719 USA Introduction A Note from the Authors The goal of this project is to determine the physical characteristics of variable stars (e.g., temperature, radius and luminosity) by analyzing spectra and photometric observations that span several years. The project was originally developed as a The 2.1-meter telescope and research project for teachers participating in the NOAO TLRBSE program. Coudé Feed spectrograph at Kitt Peak National Observatory in Ari- Please note that it is assumed that the instructor and students are familiar with the zona. The 2.1-meter telescope is concepts of photometry and spectroscopy as it is used in astronomy, as well as inside the white dome. The Coudé stellar classification and stellar evolution. This document is an incomplete source Feed spectrograph is in the right of information on these topics, so further study is encouraged. In particular, the half of the building. It also uses “Stellar Spectroscopy” document will be useful for learning how to analyze the the white tower on the right. spectrum of a star. Prerequisites To be able to do this research project, students should have a basic understanding of the following concepts: • Spectroscopy and photometry in astronomy • Stellar evolution • Stellar classification • Inverse-square law and Stefan’s law The control room for the Coudé Description of the Data Feed spectrograph. The spec- trograph is operated by the two The spectra used in this project were obtained with the Coudé Feed telescopes computers on the left. -
TAAS Observing Challenge, March 2016 Deep Sky Object
TAAS Observing Challenge, March 2016 Deep Sky Object NGC 3242 (PN) Hydra ra: 10h 24m 46.2s dec: -18° 38’ 34” Magnitude (visual) = 7.7 Size = 64” Distance = approximately 2,500 light years Description: William Herschel discovered this planetary nebula on February 7, 1785, and cataloged it as H IV.27. John Herschel observed it from the Cape of Good Hope, South Africa, in the 1830s, and numbered it as h 3248, and included it in the 1864 General Catalogue as GC 2102; this became NGC 3242 in J.L.E. Dreyer's New General Catalogue of 1888. This planetary nebula consists of a small dense nebula of about 16" x 26" in diameter, surrounded by a fainter envelop measuring about 40 x 35 arc seconds. This central nebula is embedded in a much larger faint halo, measuring 1250" or about 20.8 arc minutes in diameter. The bright inner nebula is described as looking like an eye by Burnham, and the outer shell gave rise to its popular name, as it is of about the apparent size of Jupiter. This planetary nebula is most frequently called the Ghost of Jupiter, or Jupiter's Ghost, but it is also sometimes referred to as the Eye Nebula, or the CBS Eye. Source: http://messier.seds.org/spider/Misc/n3242.html AL: Herschel 400, Caldwell [59]; TAAS 200 Challenge Object NGC 3962 (GX) Crater ra: 11h 54m 40.0s dec: -13° 58’ 34” Magnitude (visual) = 10.7 Size = 2.6’ x 2.2’ Position angle = 10° Description: NGC3962 is a small, elliptical galaxy in the constellation of Crater. -
List of Easy Double Stars for Winter and Spring = Easy = Not Too Difficult = Difficult but Possible
List of Easy Double Stars for Winter and Spring = easy = not too difficult = difficult but possible 1. Sigma Cassiopeiae (STF 3049). 23 hr 59.0 min +55 deg 45 min This system is tight but very beautiful. Use a high magnification (150x or more). Primary: 5.2, yellow or white Seconary: 7.2 (3.0″), blue 2. Eta Cassiopeiae (Achird, STF 60). 00 hr 49.1 min +57 deg 49 min This is a multiple system with many stars, but I will restrict myself to the brightest one here. Primary: 3.5, yellow. Secondary: 7.4 (13.2″), purple or brown 3. 65 Piscium (STF 61). 00 hr 49.9 min +27 deg 43 min Primary: 6.3, yellow Secondary: 6.3 (4.1″), yellow 4. Psi-1 Piscium (STF 88). 01 hr 05.7 min +21 deg 28 min This double forms a T-shaped asterism with Psi-2, Psi-3 and Chi Piscium. Psi-1 is the uppermost of the four. Primary: 5.3, yellow or white Secondary: 5.5 (29.7), yellow or white 5. Zeta Piscium (STF 100). 01 hr 13.7 min +07 deg 35 min Primary: 5.2, white or yellow Secondary: 6.3, white or lilac (or blue) 6. Gamma Arietis (Mesarthim, STF 180). 01 hr 53.5 min +19 deg 18 min “The Ram’s Eyes” Primary: 4.5, white Secondary: 4.6 (7.5″), white 7. Lambda Arietis (H 5 12). 01 hr 57.9 min +23 deg 36 min Primary: 4.8, white or yellow Secondary: 6.7 (37.1″), silver-white or blue 8. -
Mètodes De Detecció I Anàlisi D'exoplanetes
MÈTODES DE DETECCIÓ I ANÀLISI D’EXOPLANETES Rubén Soussé Villa 2n de Batxillerat Tutora: Dolors Romero IES XXV Olimpíada 13/1/2011 Mètodes de detecció i anàlisi d’exoplanetes . Índex - Introducció ............................................................................................. 5 [ Marc Teòric ] 1. L’Univers ............................................................................................... 6 1.1 Les estrelles .................................................................................. 6 1.1.1 Vida de les estrelles .............................................................. 7 1.1.2 Classes espectrals .................................................................9 1.1.3 Magnitud ........................................................................... 9 1.2 Sistemes planetaris: El Sistema Solar .............................................. 10 1.2.1 Formació ......................................................................... 11 1.2.2 Planetes .......................................................................... 13 2. Planetes extrasolars ............................................................................ 19 2.1 Denominació .............................................................................. 19 2.2 Història dels exoplanetes .............................................................. 20 2.3 Mètodes per detectar-los i saber-ne les característiques ..................... 26 2.3.1 Oscil·lació Doppler ........................................................... 27 2.3.2 Trànsits