In This Issue: Astrophysical Journal Letters and He Is the Author of Six Books and More Than 230 Articles on Theoretical 1….General Meeting Astrophysics
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Arxiv:2104.03323V2 [Astro-Ph.SR] 9 Apr 2021 Pending on the Metallicity and Modeling Assumptions (E.G., Lar- Son & Starrfield 1971; Oey & Clarke 2005)
Astronomy & Astrophysics manuscript no. main ©ESO 2021 April 12, 2021 The Tarantula Massive Binary Monitoring V. R 144 – a wind-eclipsing binary with a total mass & 140 M * T. Shenar1, H. Sana1, P. Marchant1, B. Pablo2, N. Richardson3, A. F. J. Moffat4, T. Van Reeth1, R. H. Barbá5, D. M. Bowman1, P. Broos6, P. A. Crowther7, J. S. Clark8†, A. de Koter9, S. E. de Mink10; 9; 11, K. Dsilva1, G. Gräfener12, I. D. Howarth13, N. Langer12, L. Mahy1; 14, J. Maíz Apellániz15, A. M. T. Pollock7, F. R. N. Schneider16; 17, L. Townsley6, and J. S. Vink18 (Affiliations can be found after the references) Received March 02, 2021; accepted April 06, 2021 ABSTRACT Context. The evolution of the most massive stars and their upper-mass limit remain insufficiently constrained. Very massive stars are characterized by powerful winds and spectroscopically appear as hydrogen-rich Wolf-Rayet (WR) stars on the main sequence. R 144 is the visually brightest WR star in the Large Magellanic Cloud (LMC). R 144 was reported to be a binary, making it potentially the most massive binary thus observed. However, the orbit and properties of R 144 are yet to be established. Aims. Our aim is to derive the physical, atmospheric, and orbital parameters of R 144 and interpret its evolutionary status. Methods. We perform a comprehensive spectral, photometric, orbital, and polarimetric analysis of R 144. Radial velocities are measured via cross- correlation. Spectral disentangling is performed using the shift-and-add technique. We use the Potsdam Wolf-Rayet (PoWR) code for the spectral analysis. We further present X-ray and optical light-curves of R 144, and analyse the latter using a hybrid model combining wind eclipses and colliding winds to constrain the orbital inclination i. -
Prehistory of Transit Searches Danielle BRIOT1 & Jean
Prehistory of Transit Searches Danielle BRIOT1 & Jean SCHNEIDER2 1) GEPI, UMR 8111, Observatoire de Paris, 61 avenue de l’Observatoire, F- 75014, Paris, France [email protected] 2) LUTh, UMR 8102, Observatoire de Paris, 5 place Jules Janssen, F-92195 Meudon Cedex, France [email protected] Abstract Nowadays the more powerful method to detect extrasolar planets is the transit method, that is to say observations of the stellar luminosity regularly decreasing when the planet is transiting the star. We review the planet transits which were anticipated, searched, and the first ones which were observed all through history. Indeed transits of planets in front of their star were first investigated and studied in the solar system, concerning the star Sun. The first observations of sunspots were sometimes mistaken for transits of unknown planets. The first scientific observation and study of a transit in the solar system was the observation of Mercury transit by Pierre Gassendi in 1631. Because observations of Venus transits could give a way to determine the distance Sun-Earth, transits of Venus were overwhelmingly observed. Some objects which actually do not exist were searched by their hypothetical transits on the Sun, as some examples a Venus satellite and an infra-mercurial planet. We evoke the possibly first use of the hypothesis of an exoplanet transit to explain some periodic variations of the luminosity of a star, namely the star Algol, during the eighteen century. Then we review the predictions of detection of exoplanets by their transits, those predictions being sometimes ancient, and made by astronomers as well as popular science writers. -
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. -
Apus Constellation Visible at Latitudes Between +5° and -90°
Apus Constellation Visible at latitudes between +5° and -90°. Best visible at 21:00 (9 p.m.) during the month of July. Apus is a small constellation in the southern sky. It represents a bird-of-paradise, and its name means "without feet" in Greek because the bird-of-paradise was once wrongly believed to lack feet. First depicted on a celestial globe by Petrus Plancius in 1598, it was charted on a star atlas by Johann Bayer in his 1603 Uranometria. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756. The five brightest stars are all reddish in hue. Shading the others at apparent magnitude 3.8 is Alpha Apodis, an orange giant that has around 48 times the diameter and 928 times the luminosity of the Sun. Marginally fainter is Gamma Apodis, another ageing giant star. Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible with the naked eye. Two star systems have been found to have planets. Apus was one of twelve constellations published by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman who had sailed on the first Dutch trading expedition, known as the Eerste Schipvaart, to the East Indies. It first appeared on a 35-cm diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius. De Houtman included it in his southern star catalogue in 1603 under the Dutch name De Paradijs Voghel, "The Bird of Paradise", and Plancius called the constellation Paradysvogel Apis Indica; the first word is Dutch for "bird of paradise". -
A Direct Communication Proposal to Test the Zoo Hypothesis
Space Policy 38 (2016) 22e26 Contents lists available at ScienceDirect Space Policy journal homepage: www.elsevier.com/locate/spacepol Viewpoint A direct communication proposal to test the Zoo Hypothesis Joao~ Pedro de Magalhaes~ Institute of Integrative Biology, University of Liverpool, Biosciences Building, Room 245, Crown Street, Liverpool, L69 7ZB, UK article info abstract Article history: Whether we are alone in the universe is one of the greatest mysteries facing humankind. Given the >100 Received 3 March 2016 billion stars in our galaxy, many have argued that it is statistically unlikely that life, including intelligent Accepted 16 June 2016 life, has not emerged anywhere else. The lack of any sign of extraterrestrial intelligence, even though on a Available online 26 July 2016 cosmic timescale extraterrestrial civilizations would have enough time to cross the galaxy, is known as Fermi's Paradox. One possible explanation for Fermi's Paradox is the Zoo Hypothesis which states that Keywords: one or more extraterrestrial civilizations know of our existence and can reach us, but have chosen not to Active SETI disturb us or even make their existence known to us. I propose here a proactive test of the Zoo Hy- Astrobiology fi Fermi's Paradox pothesis. Speci cally, I propose to send a message using television and radio channels to any extrater- Messaging to extraterrestrial intelligence restrial civilization(s) that might be listening and inviting them to respond. Even though I accept this is METI unlikely to be successful in the sense of resulting in a response from extraterrestrial intelligences, the possibility that extraterrestrial civilizations are monitoring us cannot be dismissed and my proposal is consistent with current scientific knowledge. -
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. -
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. -
Download the 2016 Spring Deep-Sky Challenge
Deep-sky Challenge 2016 Spring Southern Star Party Explore the Local Group Bonnievale, South Africa Hello! And thanks for taking up the challenge at this SSP! The theme for this Challenge is Galaxies of the Local Group. I’ve written up some notes about galaxies & galaxy clusters (pp 3 & 4 of this document). Johan Brink Peter Harvey Late-October is prime time for galaxy viewing, and you’ll be exploring the James Smith best the sky has to offer. All the objects are visible in binoculars, just make sure you’re properly dark adapted to get the best view. Galaxy viewing starts right after sunset, when the centre of our own Milky Way is visible low in the west. The edge of our spiral disk is draped along the horizon, from Carina in the south to Cygnus in the north. As the night progresses the action turns north- and east-ward as Orion rises, drawing the Milky Way up with it. Before daybreak, the Milky Way spans from Perseus and Auriga in the north to Crux in the South. Meanwhile, the Large and Small Magellanic Clouds are in pole position for observing. The SMC is perfectly placed at the start of the evening (it culminates at 21:00 on November 30), while the LMC rises throughout the course of the night. Many hundreds of deep-sky objects are on display in the two Clouds, so come prepared! Soon after nightfall, the rich galactic fields of Sculptor and Grus are in view. Gems like Caroline’s Galaxy (NGC 253), the Black-Bottomed Galaxy (NGC 247), the Sculptor Pinwheel (NGC 300), and the String of Pearls (NGC 55) are keen to be viewed. -
407 a Abell Galaxy Cluster S 373 (AGC S 373) , 351–353 Achromat
Index A Barnard 72 , 210–211 Abell Galaxy Cluster S 373 (AGC S 373) , Barnard, E.E. , 5, 389 351–353 Barnard’s loop , 5–8 Achromat , 365 Barred-ring spiral galaxy , 235 Adaptive optics (AO) , 377, 378 Barred spiral galaxy , 146, 263, 295, 345, 354 AGC S 373. See Abell Galaxy Cluster Bean Nebulae , 303–305 S 373 (AGC S 373) Bernes 145 , 132, 138, 139 Alnitak , 11 Bernes 157 , 224–226 Alpha Centauri , 129, 151 Beta Centauri , 134, 156 Angular diameter , 364 Beta Chamaeleontis , 269, 275 Antares , 129, 169, 195, 230 Beta Crucis , 137 Anteater Nebula , 184, 222–226 Beta Orionis , 18 Antennae galaxies , 114–115 Bias frames , 393, 398 Antlia , 104, 108, 116 Binning , 391, 392, 398, 404 Apochromat , 365 Black Arrow Cluster , 73, 93, 94 Apus , 240, 248 Blue Straggler Cluster , 169, 170 Aquarius , 339, 342 Bok, B. , 151 Ara , 163, 169, 181, 230 Bok Globules , 98, 216, 269 Arcminutes (arcmins) , 288, 383, 384 Box Nebula , 132, 147, 149 Arcseconds (arcsecs) , 364, 370, 371, 397 Bug Nebula , 184, 190, 192 Arditti, D. , 382 Butterfl y Cluster , 184, 204–205 Arp 245 , 105–106 Bypass (VSNR) , 34, 38, 42–44 AstroArt , 396, 406 Autoguider , 370, 371, 376, 377, 388, 389, 396 Autoguiding , 370, 376–378, 380, 388, 389 C Caldwell Catalogue , 241 Calibration frames , 392–394, 396, B 398–399 B 257 , 198 Camera cool down , 386–387 Barnard 33 , 11–14 Campbell, C.T. , 151 Barnard 47 , 195–197 Canes Venatici , 357 Barnard 51 , 195–197 Canis Major , 4, 17, 21 S. Chadwick and I. Cooper, Imaging the Southern Sky: An Amateur Astronomer’s Guide, 407 Patrick Moore’s Practical -
VIRTUAL CONCEPT > REAL PROFIT
B K C L OZE ULKA OE M > K , VIRTUAL CONCEPT REAL PROFIT S , [ed.] AWSKI with Digital Manufacturing and Simulation IR E , S , , , O VIRTUAL CONCEPT In our highly competitive industrialized world of lean production TT O and fast innovation, it comes as no surprise that customers demand CASA Yves Coze instantaneous delivery of individualized products at the best price- , , > performance ratio. For manufacturing companies, vast product REAL PROFIT ranges of high quality and complexity mean that flexible develop- with Digital Manufacturing and Simulation VIRTUAL CONCEPT ment and ramp-up across supply chain networks is crucial to survive with Digital Manufacturing and Simulation and thrive. Global competition, economic pressure, environmental and energy issues demand state-of-the-art capabilities and, above all, timely action. Such formidable challenges can only be met by Nicolas Kawski tightly interwoven lifecycle-oriented engineering and manufactur- ing technologies and processes. To date more than ever, the ongoing development and integration of digital manufacturing and simu- lation is critical to eliminate the waste of time and money in the physical world, and to ensure product success as much and as early as possible. Torsten Kulka Digital manufacturing and simulation clearly constitute contempo- rary extensions of the train of thought and practice that Frederick Winslow Taylor started a century ago. The evolution from “Taylor- > made” to “tailor-made” is in perfect concert with the ongoing REAL PROFIT customization that customers have learned not only to demand but to even co-create. Apart from lowering cost and improving time- to-market, digital manufacturing and simulation are targeted at Pascal Sire intensifying the intimacy, efficiency and effectiveness of co-creation feedback loops, fostering the collaboration of manufacturers, cus- tomer communities, independent R&D institutes and individuals. -
Hubble Peeks Inside a Stellar Cloud 23 April 2012
Image: Hubble peeks inside a stellar cloud 23 April 2012 It is thought that most of the stars in the Milky Way were born in OB associations. There are several such groupings of stars in the LMC. Just like the others, LH 88 consists of several high-mass young stars in a large nebula of partially ionized hydrogen gas, and lies in what is known to be a supergiant shell of gas called LMC 4. Over a period of several million years, thousands of stars may form in these supergiant shells, which are the largest interstellar structures in galaxies. The shells themselves are believed to have been created by strong stellar winds and clustered supernova explosions of massive stars that blow away surrounding dust and gas, and in turn trigger further episodes of star formation. The LMC is the third closest galaxy to our Milky Way. It is located some 160 000 light-years away, and is about 100 times smaller than our own.This image, which shows ultraviolet, visible and infrared Credit: ESA/Hubble, NASA and D. A Gouliermis. Acknowledgement: Flickr user Eedresha Sturdivant light, covers a field of view of approximately 1.8 by 1.8 arcminutes. A version of this image was entered into the (Phys.org) -- These bright stars shining through Hubble's Hidden Treasures Image Processing what looks like a haze in the night sky are part of a Competition by contestant Eedresha Sturdivant. young stellar grouping in one of the largest known Hidden Treasures is an initiative to invite astronomy star formation regions of the Large Magellanic enthusiasts to search the Hubble archive for Cloud (LMC), a dwarf satellite galaxy of the Milky stunning images that have never been seen by the Way. -
Observer Page 2 of 12
AAAssstttrrrooonnnooomyyy CCCllluuubbb ooofff TTTuuulllsssaaa OOOOOObbbbbbsssssseeeeeerrrrrrvvvvvveeeeeerrrrrr January 2009 Picture of the Month Mirach’s Ghost – NGC 404 / Herschel II-224 As far as ghosts go, Mirach's Ghost isn't really that scary. In fact, Mirach's Ghost is just a faint, fuzzy galaxy, well known to astronomers, that happens to be seen nearly along the line-of-sight to Mirach, a bright star. Centered in this star field, Mirach is also called Beta Andromedae. About 200 light-years distant, Mirach is a red giant star, cooler than the Sun but much larger and so intrinsically much brighter than our parent star. In most telescopic views, glare and diffraction spikes tend to hide things that lie near Mirach and make the faint, fuzzy galaxy look like a ghostly internal reflection of the almost overwhelming starlight. Still, appearing in this sharp image just above and to the right, Mirach's Ghost is cataloged as galaxy NGC 404 and is estimated to be some 10 million light-years away. – Explanation from APOD/NASA Credit & Copyright – Anthony Ayiomamitis (Athens, Greece) Website = http://www.perseus.gr/ & eMail = [email protected] Inside This Issue: Important ACT Upcoming Dates: Vice President's Message - p2 IYoA - - - - - - - - - - - - - - - p6 Public Star Party… Fri. January 2, 2009 (p11) Word Search Puzzle - - - - p3 Virtual Moon Atlas - - - - - - p7 ACT Meeting @ TCC - Fri. January 9, ( 7pm ) January Stars - - - - - - - - p4 Observing Pages - - - - pp 8- 9 Members Only Star Party … Fri. January 23, 2009 Planetarium News - - - - - p5 Land’s Tidbits - - - - - - - - p10 ACT Observer Page 2 of 12 Vice President’s Message by Tom Mcdonough Happy New Year to everyone, we have a very exciting year ahead of us! 2009 is the International Year of Astronomy in celebration of the 400th anniversary of Galileo’s observations of the heavens with one of the first telescopes.