Starview Visible Object Listing For: April 15, 2017 Local Time (Z4
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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. -
Naming the Extrasolar Planets
Naming the extrasolar planets W. Lyra Max Planck Institute for Astronomy, K¨onigstuhl 17, 69177, Heidelberg, Germany [email protected] Abstract and OGLE-TR-182 b, which does not help educators convey the message that these planets are quite similar to Jupiter. Extrasolar planets are not named and are referred to only In stark contrast, the sentence“planet Apollo is a gas giant by their assigned scientific designation. The reason given like Jupiter” is heavily - yet invisibly - coated with Coper- by the IAU to not name the planets is that it is consid- nicanism. ered impractical as planets are expected to be common. I One reason given by the IAU for not considering naming advance some reasons as to why this logic is flawed, and sug- the extrasolar planets is that it is a task deemed impractical. gest names for the 403 extrasolar planet candidates known One source is quoted as having said “if planets are found to as of Oct 2009. The names follow a scheme of association occur very frequently in the Universe, a system of individual with the constellation that the host star pertains to, and names for planets might well rapidly be found equally im- therefore are mostly drawn from Roman-Greek mythology. practicable as it is for stars, as planet discoveries progress.” Other mythologies may also be used given that a suitable 1. This leads to a second argument. It is indeed impractical association is established. to name all stars. But some stars are named nonetheless. In fact, all other classes of astronomical bodies are named. -
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. -
Wynyard Planetarium & Observatory a Autumn Observing Notes
Wynyard Planetarium & Observatory A Autumn Observing Notes Wynyard Planetarium & Observatory PUBLIC OBSERVING – Autumn Tour of the Sky with the Naked Eye CASSIOPEIA Look for the ‘W’ 4 shape 3 Polaris URSA MINOR Notice how the constellations swing around Polaris during the night Pherkad Kochab Is Kochab orange compared 2 to Polaris? Pointers Is Dubhe Dubhe yellowish compared to Merak? 1 Merak THE PLOUGH Figure 1: Sketch of the northern sky in autumn. © Rob Peeling, CaDAS, 2007 version 1.2 Wynyard Planetarium & Observatory PUBLIC OBSERVING – Autumn North 1. On leaving the planetarium, turn around and look northwards over the roof of the building. Close to the horizon is a group of stars like the outline of a saucepan with the handle stretching to your left. This is the Plough (also called the Big Dipper) and is part of the constellation Ursa Major, the Great Bear. The two right-hand stars are called the Pointers. Can you tell that the higher of the two, Dubhe is slightly yellowish compared to the lower, Merak? Check with binoculars. Not all stars are white. The colour shows that Dubhe is cooler than Merak in the same way that red-hot is cooler than white- hot. 2. Use the Pointers to guide you upwards to the next bright star. This is Polaris, the Pole (or North) Star. Note that it is not the brightest star in the sky, a common misconception. Below and to the left are two prominent but fainter stars. These are Kochab and Pherkad, the Guardians of the Pole. Look carefully and you will notice that Kochab is slightly orange when compared to Polaris. -
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). -
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. -
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. -
October 2020
The Newsletter of Westchester Amateur Astronomers October 2020 Pelican Nebula (IC 5070 and 5067) by Olivier Prache Imaged from Olivier’s observatory in Pleasantville. Borg 101ED and ZWO ASI071MC one-shot-color camera using an Optolong L-Enhance filter. Three hours of five-minute subs (unguided) and a bit of work with PixInsight. SERVING THE ASTRONOMY COMMUNITY SINCE 1986 1 Westchester Amateur Astronomers SkyWAAtch October 2020 WAA October Meeting WAA November Meeting Friday, October 2 at 7:30 pm Friday, November at 6 7:30 pm On-line via Zoom On-line via Zoom Intelligent Nighttime Lighting: The Many BLACK HOLES: Not so black? Benefits of Dark Skies Willie Yee Charles Fulco Recent years have seen major breakthroughs in the Science educator Charles Fulco will discuss the meth- study of black holes, including the first image of a ods and many benefits of reducing light pollution, black hole from the Event Horizon Telescope and the including energy and tax dollar savings, health bene- detection of black hole collisions with the Laser fits and of course seeing the Milky Way again. Invita- Interferometer Gravitational-wave Observatory. tions and log-in instructions will be sent to WAA Dr. Yee, a NASA Solar System Ambassador and Past members via email. President of the Mid-Hudson Astronomical Association, will review the basic science of black Starway to Heaven holes and the myths surrounding them, and present Ward Pound Ridge Reservation, the recent findings of these projects. Cross River, NY Call: 1-877-456-5778 (toll free) for announcements, Scheduled for Oct 10th (rain/cloud date Oct 17). -
Starview Visible Object Listing For: March 15, 2017 Local Time
StarView Visible Object Listing for: March 15, Local Time (Z5): Lat: Minimum Criteria: 2017 21:30 41.5 Elev: 5° / Mag: 6 Sidereal Time: Lon: Sep: 10 arcmin / Size: 08:39 81.5 2 arcsec Name Con Type Mag Sep/Size Elev Spiral M31 Andromeda Galaxy And 3.44 190 arcmin 9° Galaxy Open 30x75 Little Fish Aur 4.5 50° Cluster arcmin Double kappa Bootes Asellus Tertius Boo 4.5, 6.6 13.4 arcsec 35° Star Double 0.8, 99 Zeta Bootis Boo 4.6, 4.5 9° Star arcsec Double Iota Cancri Can 4.2, 6.6 30.6 arcsec 77° Star Open M44 Beehive Cluster, Praesepe Can 3.7 95 arcmin 68° Cluster Double Eta Cassiopeiae Achrid Cas 3.4, 7.5 13 arcsec 22° Star Delta Cephei Cep Star 4 13° Double 145 Canis Majoris h3945 Cma 4.8, 6.8 27 arcsec 22° Star Beta Canis Majoris Murzim Cma Star 2 23° Delta Canis Majoris Wezen Cma Star 1.8 19° Eta Canis Majoris Aludra Cma Star 2.4 17° Gamma Canis Majoris Cma Star 4.1 29° Muliphein Open M41 Cma 4.5 38 arcmin 22° Cluster Zeta Canis Majoris Phurud Cma Star 3.02 12° Double 24 Comae Berenices Com 5.2, 6.7 20.3 arcsec 35° Star Double 35 Comae Berenices Com 4.91 29 arcsec 33° Star Alpha Canum Venaticorum Cor CVn Double 2.9, 5.5 19.6 arcsec 42° Caroli Star Y Cvn La Superba Cvn Star 5 46° Double Nu Draconis Dra 4.88 63.4 arcsec 14° Star Omicron 2 Eridani Keid, Beid, Double Eri 4.5.