The View from up Here Calendar July Meeting Notes Star Party At
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Unknown Amorphous Carbon II. LRS SPECTRA the Sample Consists Of
Table I A summary of the spectral -features observed in the LRS spectra of the three groups o-f carbon stars. The de-finition o-f the groups is given in the text. wavelength Xmax identification Group I B - 12 urn E1 9.7 M™ Silicate 12 - 23 jim E IB ^m Silicate Group II < 8.5 M"i A C2H2 CS? 12 - 16 f-i/n A 13.7 - 14 Mm C2H2 HCN? 8 - 10 Mm E 8.6 M"i Unknown 10 - 13 Mm E 11.3 - 11 .7 M«> SiC Group III 10 - 13 MJn E 11.3 - 11 .7 tun SiC B - 23 Htn C Amorphous carbon 1 The letter in this column indicates the nature o-f the -feature: A = absorption; E = emission; C indicates the presence of continuum opacity. II. LRS SPECTRA The sample consists of 304 carbon stars with entries in the LRS catalog (Papers I-III). The LRS spectra have been divided into three groups. Group I consists of nine stars with 9.7 and 18 tun silicate features in their LRS spectra pointing to oxygen-rich dust in the circumstellar shell. These sources are discussed in Paper I. The remaining stars all have spectra with carbon-rich dust features. Using NIR photometry we have shown that in the group II spectra the stellar photosphere is the dominant continuum. The NIR color temperature is of the order of 25OO K. Paper II contains a discussion of sources with this class of spectra. The continuum in the group III spectra is probably due to amorphous carbon dust. -
Sky Notes by Neil Bone 2005 August & September
Sky notes by Neil Bone 2005 August & September below Castor and Pollux. Mercury is soon ing June and July, it is still quite possible that Sun and Moon lost from view again, arriving at superior con- noctilucent clouds (NLC) could be seen into junction beyond the Sun on September 18. early August, particularly by observers at The Sun continues its southerly progress along Venus continues its rather unfavourable more northerly locations. Quite how late into the ecliptic, reaching the autumnal equinox showing as an ‘Evening Star’. Although it August NLC can be seen remains to be deter- position at 22h 23m Universal Time (UT = pulls out to over 40° elongation east of the mined: there have been suggestions that the GMT; BST minus 1 hour) on September 22. Sun during September, Venus is also heading visibility period has become longer in recent At that precise time, the centre of the solar southwards, and as a result its setting-time years. Observational reports will be welcomed disk is positioned at the intersection between after the Sun remains much the same − barely by the Aurora Section. the celestial equator and the ecliptic, the latter an hour − during this interval. Although bright While declining sunspot activity makes great circle on the sky being inclined by 23.5° at magnitude −4, Venus will be quite tricky major aurorae extending to lower latitudes to the former. Calendrical autumn begins at the to catch in the early twilight: viewing cir- less likely, the appearance of coronal holes equinox, but amateur astronomers might more cumstances don’t really improve until the in the latter parts of the cycle does bring the readily follow meteorological timing, wherein closing weeks of 2005. -
A Basic Requirement for Studying the Heavens Is Determining Where In
Abasic requirement for studying the heavens is determining where in the sky things are. To specify sky positions, astronomers have developed several coordinate systems. Each uses a coordinate grid projected on to the celestial sphere, in analogy to the geographic coordinate system used on the surface of the Earth. The coordinate systems differ only in their choice of the fundamental plane, which divides the sky into two equal hemispheres along a great circle (the fundamental plane of the geographic system is the Earth's equator) . Each coordinate system is named for its choice of fundamental plane. The equatorial coordinate system is probably the most widely used celestial coordinate system. It is also the one most closely related to the geographic coordinate system, because they use the same fun damental plane and the same poles. The projection of the Earth's equator onto the celestial sphere is called the celestial equator. Similarly, projecting the geographic poles on to the celest ial sphere defines the north and south celestial poles. However, there is an important difference between the equatorial and geographic coordinate systems: the geographic system is fixed to the Earth; it rotates as the Earth does . The equatorial system is fixed to the stars, so it appears to rotate across the sky with the stars, but of course it's really the Earth rotating under the fixed sky. The latitudinal (latitude-like) angle of the equatorial system is called declination (Dec for short) . It measures the angle of an object above or below the celestial equator. The longitud inal angle is called the right ascension (RA for short). -
The Planets for 1955 24 Eclipses, 1955 ------29 the Sky and Astronomical Phenomena Month by Month - - 30 Phenomena of Jupiter’S S a Te Llite S
THE OBSERVER’S HANDBOOK FOR 1955 PUBLISHED BY The Royal Astronomical Society of Canada C. A. C H A N T, E d ito r RUTH J. NORTHCOTT, A s s is t a n t E d ito r DAVID DUNLAP OBSERVATORY FORTY-SEVENTH YEAR OF PUBLICATION P r i c e 50 C e n t s TORONTO 13 Ross S t r e e t Printed for th e Society By the University of Toronto Press THE ROYAL ASTRONOMICAL SOCIETY OF CANADA The Society was incorporated in 1890 as The Astronomical and Physical Society of Toronto, assuming its present name in 1903. For many years the Toronto organization existed alone, but now the Society is national in extent, having active Centres in Montreal and Quebec, P.Q.; Ottawa, Toronto, Hamilton, London, and Windsor, Ontario; Winnipeg, Man.; Saskatoon, Sask.; Edmonton, Alta.; Vancouver and Victoria, B.C. As well as nearly 1000 members of these Canadian Centres, there are nearly 400 members not attached to any Centre, mostly resident in other nations, while some 200 additional institutions or persons are on the regular mailing list of our publications. The Society publishes a bi-monthly J o u r n a l and a yearly O b s e r v e r ’s H a n d b o o k . Single copies of the J o u r n a l are 50 cents, and of the H a n d b o o k , 50 cents. Membership is open to anyone interested in astronomy. Annual dues, $3.00; life membership, $40.00. -
By John Dobson San Francisco Sidewalk Astronomers
the newsletter of the QUEEN ELIZABET H PLANETARIUM SUMMER 198 0 and the EDMONTON CENTRE, RAS C 50$ y SPECIAL TELESCOP E ISSU E NOW PLAYIN G AT QUEEN PlANETARiUM A spectacular celestial event was witnessed by th e ancien t Sumeria n civilizatio n an d ""VELA recorded i n thei r mysteriou s cuneifor m writing. Wha t wa s it ? Th e Vela Apparition APPARITION blends archaeolog y wit h astronom y i n a search for the origins o f civilzation. 3 P M and 8 P M Daily one The night sk y i s a fascinating -realm. Stars, nebulae, an d galaxie s ar e scattere d SUMMER'S throughout infinity . Join us for a tour of the sights o f th e summertim e sky . Rela x and NIGHT enjoy an evening at the Planetarium durin g One Summer's Night. 9PM Dail y A special show for special people age 3 to 7. A Fantasy O f Stars chronicle s th e FANTASY adventures o f Harol d th e Her o a s h e ventures int o th e nigh t sk y t o mee t th e constellations. A reduced admission of only o, STARS 50C for everyon e applies to thi s 3 5 minute live presentation. For more •information , „ , please phone th re Planetariu•• , , 1:3m at 0 P M Wed . and Sun . 455-0119 Vol. 2 5 No . 1 0 StOPCll SUMMER 198 0 Have Telescopes , Will Travel JOH N DOBSO N 1 0 People came from all over the city by bus, by car, by bicycle, and by foot to look through the telescope. -
A Review of the Disc Instability Model for Dwarf Novae, Soft X-Ray Transients and Related Objects a J.M
A review of the disc instability model for dwarf novae, soft X-ray transients and related objects a J.M. Hameury aObservatoire Astronomique de Strasbourg ARTICLEINFO ABSTRACT Keywords: I review the basics of the disc instability model (DIM) for dwarf novae and soft-X-ray transients Cataclysmic variable and its most recent developments, as well as the current limitations of the model, focusing on the Accretion discs dwarf nova case. Although the DIM uses the Shakura-Sunyaev prescription for angular momentum X-ray binaries transport, which we know now to be at best inaccurate, it is surprisingly efficient in reproducing the outbursts of dwarf novae and soft X-ray transients, provided that some ingredients, such as irradiation of the accretion disc and of the donor star, mass transfer variations, truncation of the inner disc, etc., are added to the basic model. As recently realized, taking into account the existence of winds and outflows and of the torque they exert on the accretion disc may significantly impact the model. I also discuss the origin of the superoutbursts that are probably due to a combination of variations of the mass transfer rate and of a tidal instability. I finally mention a number of unsolved problems and caveats, among which the most embarrassing one is the modelling of the low state. Despite significant progresses in the past few years both on our understanding of angular momentum transport, the DIM is still needed for understanding transient systems. 1. Introduction tems using Doppler tomography techniques (Steeghs et al. 1997; Marsh and Horne 1988; see also Marsh and Schwope Dwarf novae (DNe) are cataclysmic variables (CV) that 2016 for a recent review). -
Present Status and Future Directions of the EVN
http://www.evlbi.org/ Present status and future directions of the EVN Michael Lindqvist, Onsala Space Observatory Zsolt Paragi, JIVE Onsala Space Observatory http://www.evlbi.org/ Thanks Tasso! Onsala Space Observatory http://www.evlbi.org/ VLBI science • Radio jet & black hole physics • Radio source evolution • Astrometry • Galactic and extra-galactic masers • Gravitational lenses • Supernovae and gamma-ray-burst studies • Nearby and distant starburst galaxies • Nature of faint radio source population • HI absorption studies in AGN • Space science VLBI • Transients • SETI Onsala Space Observatory http://www.evlbi.org/ Description of the EVN • The European VLBI Network (EVN) was formed in 1980. Today it includes 15 major institutes, including the Joint Institute for VLBI ERIC, JIVE • JIVE operates EVN correlator. JIVE is also involved in supporting EVN users and operations of EVN as a facility. JIVE has officially been established as an European Research Infrastructure Consortium (ERIC). • The EVN operates an “open sky” policy • No standing centralised budget for the EVN - distributed European facility Onsala Space Observatory http://www.evlbi.org/ The network Onsala Space Observatory http://www.evlbi.org/ EVN and e-VLBI From tape reel to intercontinental light paths • Pieces falling into place around 2003: – Introduction of Mark5 recording system (game changer) by Haystack Observatory – Emergence of high bandwidth optical fibre networks e-VLBI JIVE Hot scienceJIVE • The development of e-VLBI has been spearheaded by the JIVE/EVN (EXPReS, Garrett) • In this way, the EVN/JIVE is a recognized SKA pathfinder Onsala Space Observatory http://www.evlbi.org/ e-VLBI - rapid turn-around • e-VLBI has made rapid turn-around possible – X-ray, γ-ray binaries in flaring states (including novae) – AGN γ-ray outbursts — locus of VHE emission – Other high-energy flaring (e.g., Crab) – Outbursts in Mira variables (spectral-line) – Just-exploded GRBs, SNe – Binaries (incl. -
Homework 6 – Stellar Physics 1. Cygnus X-1 Is an X-Ray Source In
Homework 6 – Stellar Physics 1. Cygnus X-1 is an x-ray source in the constellation Cygnus that astrophysicists believe is a black hole. An artist’s impression is shown in Figure 1A. Figure 1A The mass of the black hole has been determined to be 14∙8 solar masses. (a) (i) State what is meant by the Schwarzschild radius of a black hole. (ii) Calculate the Schwarzchild radius of the black hole in Cygnus X-1. (b) The Hertzsprung-Russell (H-R) diagram shown in Figure 1B shows the relationship between luminosity and surface temperature of stars. Figure 1B Zeta Cygni B and Chi Cygni are two stars in the constellation Cygnus. They are shown on the H-R diagram. Chi Cygni is more luminous than Zeta Cygni B. Describe two other differences between these stars. (c) Another star, Aldebaran B, is a distance of 6∙16 x 1017 m from the Earth. The luminosity of Aldebaran B is 2∙32 x 1025 W and its temperature is determined to be 3∙4 x 103 K. (i) Calculate the radius of Aldebaran B. (ii) Calculate the apparent brightness of Aldebaran B as observed from Earth. 1 2. Hertzsprung-Russell (H-R) diagrams are widely used by physicists and astronomers to categorise stars. Figure 2A shows a simplified H-R diagram. Figure 2A (a) State what class of star Sirius B is. (b) Estimate the radius of Betelgeuse. (c) Ross 128 and Barnard’s Star have a similar temperature but Barnard’s Star has a slightly greater luminosity. Determine what other information this tells you about the two stars. -
Cygnus a Monthly Sky Guide for the Beginning to Intermediate Amateur Astronomer Tom Trusock 10-Aug-2005
Small Wonders: Cygnus A monthly sky guide for the beginning to intermediate amateur astronomer Tom Trusock 10-Aug-2005 Figure 1: Widefield Map 2/16 Small Wonders: Cygnus Target List Object Type Size Mag RA Dec α (alpha) Cygni (Deneb) Star 1.3 20h 41m 38.7s 45 17' 59" β (beta) Cygni (Albireo) Star 3 19h 30m 57.9s 27 58' 18" NGC 7000 Bright Nebula 120.0'x100.0' 4 20h 59m 03.2s 44 32' 16" IC 5070 Bright Nebula 60.0'x50.0' 8 20h 51m 01.1s 44 12' 13" NGC 6960 Supernova Remnant 70.0'x6.0' 7 20h 45m 57.0s 30 44' 12" NGC 6979 Bright Nebula 7.0'x3.0' 20h 51m 14.9s 32 10' 14" NGC 6992 Bright Nebula 60.0'x8.0' 7 20h 56m 39.0s 31 44' 16" M 29 Open Cluster 10.0' 6.6 20h 24m 11.6s 38 30' 58" M 39 Open Cluster 31.0' 4.6 21h 32m 10.4s 48 26' 40" NGC 6826 Planetary Nebula 36" 8.8 19h 44m 58.8s 50 32' 21" NGC 7026 Planetary Nebula 45" 10.9 21h 06m 31.4s 47 52' 28" NGC 6888 Bright Nebula 18.0'x13.0' 10 20h 12m 20.0s 38 22' 18" NGC 6946 Galaxy 11.5'x9.8' 9 20h 35m 01.0s 60 10' 19" Challenge Objects Object Type Size Mag RA Dec PK 64+ 5.1 Planetary Nebula 5" 9.6 19h 35m 02.3s 30 31' 45" Sh2-112 9.0'x7.0' Cygnus ygnus is a spectacular summer constellation. -
Variable Star
Variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) fluctuates. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as either: Intrinsic variables, whose luminosity actually changes; for example, because the star periodically swells and shrinks. Extrinsic variables, whose apparent changes in brightness are due to changes in the amount of their light that can reach Earth; for example, because the star has an orbiting companion that sometimes Trifid Nebula contains Cepheid variable stars eclipses it. Many, possibly most, stars have at least some variation in luminosity: the energy output of our Sun, for example, varies by about 0.1% over an 11-year solar cycle.[1] Contents Discovery Detecting variability Variable star observations Interpretation of observations Nomenclature Classification Intrinsic variable stars Pulsating variable stars Eruptive variable stars Cataclysmic or explosive variable stars Extrinsic variable stars Rotating variable stars Eclipsing binaries Planetary transits See also References External links Discovery An ancient Egyptian calendar of lucky and unlucky days composed some 3,200 years ago may be the oldest preserved historical document of the discovery of a variable star, the eclipsing binary Algol.[2][3][4] Of the modern astronomers, the first variable star was identified in 1638 when Johannes Holwarda noticed that Omicron Ceti (later named Mira) pulsated in a cycle taking 11 months; the star had previously been described as a nova by David Fabricius in 1596. This discovery, combined with supernovae observed in 1572 and 1604, proved that the starry sky was not eternally invariable as Aristotle and other ancient philosophers had taught. -
Desert Skies
Desert Skies Tucson Amateur Astronomy Association Volume LII, Number 8 August, 2006 Jupiter Dominates the August Night Sky ♦ Learn the latest about comets at ♦ Constellation of the month the monthly meeting ♦ Grand Canyon Star Party Report ♦ Star party for U of A students ♦ Object of the Month Desert Skies: August, 2006 2 Volume LII, Number 8 Cover Photo: Imaged by Rik Hill using a C14 and a ToUCam. It's a stack of about 3600 images taken in 3 minutes time. The stacking was done with Registax 3 and the final processing with GIMP. TAAA Web Page: http://www.tucsonastronomy.org TAAA Phone Number: (520) 792-6414 Office/Position Name Phone E-mail Address President Bill Lofquist 297-6653 [email protected] Vice President Ken Shaver 762-5094 [email protected] Secretary Steve Marten 307-5237 [email protected] Treasurer Terri Lappin 977-1290 [email protected] Member-at-Large George Barber 822-2392 [email protected] Member-at-Large JD Metzger 760-8248 [email protected] Member-at-Large Teresa Plymate 883-9113 [email protected] Chief Observer Wayne Johnson 586-2244 [email protected] AL Correspondent (ALCor) Nick de Mesa 797-6614 [email protected] Astro-Imaging SIG Steve Peterson 762-8211 [email protected] Computers in Astronomy SIG Roger Tanner 574-3876 [email protected] Beginners SIG Bill Lofquist 297-6653 [email protected] Newsletter Editor George Barber 822-2392 [email protected] School Star Party -
Observing List
day month year Epoch 2000 local clock time: 4.00 Observing List for 24 7 2019 RA DEC alt az Constellation object mag A mag B Separation description hr min deg min 60 75 Andromeda Gamma Andromedae (*266) 2.3 5.5 9.8 yellow & blue green double star 2 3.9 42 19 73 111 Andromeda Pi Andromedae 4.4 8.6 35.9 bright white & faint blue 0 36.9 33 43 72 71 Andromeda STF 79 (Struve) 6 7 7.8 bluish pair 1 0.1 44 42 58 80 Andromeda 59 Andromedae 6.5 7 16.6 neat pair, both greenish blue 2 10.9 39 2 89 34 Andromeda NGC 7662 (The Blue Snowball) planetary nebula, fairly bright & slightly elongated 23 25.9 42 32.1 75 84 Andromeda M31 (Andromeda Galaxy) large sprial arm galaxy like the Milky Way 0 42.7 41 16 75 85 Andromeda M32 satellite galaxy of Andromeda Galaxy 0 42.7 40 52 75 82 Andromeda M110 (NGC205) satellite galaxy of Andromeda Galaxy 0 40.4 41 41 60 84 Andromeda NGC752 large open cluster of 60 stars 1 57.8 37 41 57 73 Andromeda NGC891 edge on galaxy, needle-like in appearance 2 22.6 42 21 89 173 Andromeda NGC7640 elongated galaxy with mottled halo 23 22.1 40 51 82 10 Andromeda NGC7686 open cluster of 20 stars 23 30.2 49 8 47 200 Aquarius 55 Aquarii, Zeta 4.3 4.5 2.1 close, elegant pair of yellow stars 22 28.8 0 -1 35 181 Aquarius 94 Aquarii 5.3 7.3 12.7 pale rose & emerald 23 19.1 -13 28 30 173 Aquarius 107 Aquarii 5.7 6.7 6.6 yellow-white & bluish-white 23 46 -18 41 26 221 Aquarius M72 globular cluster 20 53.5 -12 32 27 220 Aquarius M73 Y-shaped asterism of 4 stars 20 59 -12 38 40 181 Aquarius NGC7606 Galaxy 23 19.1 -8 29 28 219 Aquarius NGC7009