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Arxiv:1504.01453V1 [Astro-Ph.GA] 7 Apr 2015 Ences
Draft version August 9, 2018 A Preprint typeset using LTEX style emulateapj v. 03/07/07 THE WEAK CARBON MONOXIDE EMISSION IN AN EXTREMELY METAL POOR GALAXY, SEXTANS A ∗ Yong Shi1,2, 3, Junzhi Wang4,5, Zhi-Yu Zhang6, Yu Gao7,5,3, Lee Armus8, George Helou8, Qiusheng Gu1,2, 3, Sabrina Stierwalt9 Draft version August 9, 2018 ABSTRACT Carbon monoxide (CO) is one of the primary coolants of gas and an easily accessible tracer of molecular gas in spiral galaxies but it is unclear if CO plays a similar role in metal poor dwarfs. We carried out a deep observation with IRAM 30 m to search for CO emission by targeting the brightest far-IR peak in a nearby extremely metal poor galaxy, Sextans A, with 7% Solar metallicity. A weak CO J=1-0 emission is seen, which is already faint enough to place a strong constraint on the conversion factor (αCO) from the CO luminosity to the molecular gas mass that is derived from the spatially resolved dust mass map. The αCO is at least seven hundred times the Milky Way value. This indicates that CO emission is exceedingly weak in extremely metal poor galaxies, challenging its role as a coolant in these galaxies. Subject headings: galaxies: dwarf – submillimeter: ISM – galaxies: ISM 1. INTRODUCTION 2013) in low metallicity environments. Probing CO emis- Stars form out of molecular clouds (Kennicutt 1998; sion at lower metallicities establishes if CO emission can Gao & Solomon 2004). The efficient cooling of molec- be an efficient gas coolant and effective tracer of molec- ular gas is the prerequisite for gas collapse and star ular gas in metal poor galaxies both locally and in early formation. -
Planetary Nebula IC 5148 and Its Ionized Halo? D
A&A 620, A84 (2018) Astronomy https://doi.org/10.1051/0004-6361/201833981 & © ESO 2018 Astrophysics Planetary nebula IC 5148 and its ionized halo? D. Barría1, S. Kimeswenger1,2, W. Kausch2, and D. S. Goldman3 1 Instituto de Astronomía, Universidad Católica del Norte, Av. Angamos 0610, Antofagasta, Chile e-mail: [email protected] 2 Institut für Astro- und Teilchenphysik, Leopold–Franzens Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria 3 Astrodon Imaging, 407 Tyrolean Court. Roseville, California, 95661, USA Received 29 July 2018 / Accepted 2 October 2018 ABSTRACT Context. Many round or roundish planetary nebulae (PNe) show multiple shells and halo structures during their evolutionary stage near the maximum temperature of their central star. Controversial debate is ongoing if these structures are recombination halos, as suggested by hydrodynamic modeling efforts, or ionized material. Recently, we discovered a halo with somewhat unusual structures around the sparsely studied PN IC 5148 and present for the first time spectroscopy going out to the halo of such a PN. Aims. We investigate the spatial distribution of material and its ionization state from the center of the nebula up to the very outskirts of the halo. Methods. We obtained long-slit low resolution spectroscopy (FORS2 at VLT) of the nebula in two position angles, which we used to investigate the nebular structure and its halo in the optical range from 450 to 880 nm. In addition we used medium resolution spectra taken with X-shooter at VLT ranging from 320 nm to 2.4 µm to derive atmospheric parameters for the central star. We obtained the distance and position in the Galaxy from various methods combined with Gaia DR2 data. -
Filter Performance Comparisons for Some Common Nebulae
Filter Performance Comparisons For Some Common Nebulae By Dave Knisely Light Pollution and various “nebula” filters have been around since the late 1970’s, and amateurs have been using them ever since to bring out detail (and even some objects) which were difficult to impossible to see before in modest apertures. When I started using them in the early 1980’s, specific information about which filter might work on a given object (or even whether certain filters were useful at all) was often hard to come by. Even those accounts that were available often had incomplete or inaccurate information. Getting some observational experience with the Lumicon line of filters helped, but there were still some unanswered questions. I wondered how the various filters would rank on- average against each other for a large number of objects, and whether there was a “best overall” filter. In particular, I also wondered if the much-maligned H-Beta filter was useful on more objects than the two or three targets most often mentioned in publications. In the summer of 1999, I decided to begin some more comprehensive observations to try and answer these questions and determine how to best use these filters overall. I formulated a basic survey covering a moderate number of emission and planetary nebulae to obtain some statistics on filter performance to try to address the following questions: 1. How do the various filter types compare as to what (on average) they show on a given nebula? 2. Is there one overall “best” nebula filter which will work on the largest number of objects? 3. -
Messier Objects
Messier Objects From the Stocker Astroscience Center at Florida International University Miami Florida The Messier Project Main contributors: • Daniel Puentes • Steven Revesz • Bobby Martinez Charles Messier • Gabriel Salazar • Riya Gandhi • Dr. James Webb – Director, Stocker Astroscience center • All images reduced and combined using MIRA image processing software. (Mirametrics) What are Messier Objects? • Messier objects are a list of astronomical sources compiled by Charles Messier, an 18th and early 19th century astronomer. He created a list of distracting objects to avoid while comet hunting. This list now contains over 110 objects, many of which are the most famous astronomical bodies known. The list contains planetary nebula, star clusters, and other galaxies. - Bobby Martinez The Telescope The telescope used to take these images is an Astronomical Consultants and Equipment (ACE) 24- inch (0.61-meter) Ritchey-Chretien reflecting telescope. It has a focal ratio of F6.2 and is supported on a structure independent of the building that houses it. It is equipped with a Finger Lakes 1kx1k CCD camera cooled to -30o C at the Cassegrain focus. It is equipped with dual filter wheels, the first containing UBVRI scientific filters and the second RGBL color filters. Messier 1 Found 6,500 light years away in the constellation of Taurus, the Crab Nebula (known as M1) is a supernova remnant. The original supernova that formed the crab nebula was observed by Chinese, Japanese and Arab astronomers in 1054 AD as an incredibly bright “Guest star” which was visible for over twenty-two months. The supernova that produced the Crab Nebula is thought to have been an evolved star roughly ten times more massive than the Sun. -
Radio Continuum and CO Emission in Star-Forming Galaxies
A&A 385, 412–424 (2002) Astronomy DOI: 10.1051/0004-6361:20020140 & c ESO 2002 Astrophysics Radio continuum and CO emission in star-forming galaxies M. Murgia1,A.Crapsi1,2, L. Moscadelli3, and L. Gregorini1,4 1 Istituto di Radioastronomia del CNR, Via Gobetti 101, 40129, Bologna, Italy 2 Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125, Firenze, Italy 3 Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra (CA), Italy 4 Dipartimento di Fisica, Universit`a di Bologna, Via B. Pichat 6/2, 40127 Bologna, Italy Received 30 October 2001 / Accepted 23 January 2002 Abstract. We combine the radio continuum images from the NRAO VLA Sky Survey with the CO-line observations from the extragalactic CO survey of the Five College Radio Astronomy Observatory to study the relationship between molecular gas and the star formation rate within the disks of 180 spiral galaxies at 4500 resolution. We find a tight correlation between these quantities. On average, the ratio between the radio continuum and the CO emission is constant, within a factor of 3, both inside the same galaxy and from galaxy to galaxy. The mean star formation efficiency deduced from the radio continuum corresponds to convert 3.5% of the available molecular gas into stars on a time scale of 108 yr and depends weakly on general galaxy properties, such as Hubble type or nuclear activity. A comparison is made with another similar analysis performed using the Hα luminosity as star formation indicator. The overall agreement we find between the two studies reinforces the use of the radio luminosity as star formation rate indicator not only on global but also on local scales. -
Planetary Nebulae
Planetary Nebulae A planetary nebula is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. The term "planetary nebula" is a misnomer that originated in the 1780s with astronomer William Herschel because when viewed through his telescope, these objects appeared to him to resemble the rounded shapes of planets. Herschel's name for these objects was popularly adopted and has not been changed. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years. The mechanism for formation of most planetary nebulae is thought to be the following: at the end of the star's life, during the red giant phase, the outer layers of the star are expelled by strong stellar winds. Eventually, after most of the red giant's atmosphere is dissipated, the exposed hot, luminous core emits ultraviolet radiation to ionize the ejected outer layers of the star. Absorbed ultraviolet light energizes the shell of nebulous gas around the central star, appearing as a bright colored planetary nebula at several discrete visible wavelengths. Planetary nebulae may play a crucial role in the chemical evolution of the Milky Way, returning material to the interstellar medium from stars where elements, the products of nucleosynthesis (such as carbon, nitrogen, oxygen and neon), have been created. Planetary nebulae are also observed in more distant galaxies, yielding useful information about their chemical abundances. In recent years, Hubble Space Telescope images have revealed many planetary nebulae to have extremely complex and varied morphologies. -
Publications for Geraint Lewis 2021 2020
Publications for Geraint Lewis 2021 R., Horner, J., Wright, D., Carter, B., Morton, T., Spina, L., Li, T., Koposov, S., Erkal, D., Ji, A., Shipp, N., Hilmi, T., Bland-Hawthorn, J., Hayden, M., Lewis, G., Sharma, S., Kuehn, K., Pace, A., Lewis, G., Mackey, D., Wan, Z., Bland- Simpson, J., et al (2021). The GALAH Survey: Using galactic Hawthorn, J., Sharma, S., et al (2021). Broken into pieces: archaeology to refine our knowledge of TESS target stars. ATLAS and Aliqa Uma as one single stream. The Astrophysical Monthly Notices of the Royal Astronomical Society, 504(4), Journal, 911(2), 149. <a href="http://dx.doi.org/10.3847/1538- 4968-4989. <a 4357/abeb18">[More Information]</a> href="http://dx.doi.org/10.1093/mnras/stab1052">[More Information]</a> Sharma, S., Hayden, M., Bland-Hawthorn, J., Stello, D., Buder, S., Zinn, J., Kallinger, T., Asplund, M., De Silva, G., D'Orazi, Oliver, W., Elahi, P., Lewis, G., Power, C. (2021). The V., Kos, J., Lewis, G., Lin, J., Zucker, D., Chen, B., Huber, D., hierarchical structure of galactic haloes: Classification and Kafle, P., Khanna, S., et al (2021). Fundamental relations for characterization with halo-optics. Monthly Notices of the Royal the velocity dispersion of stars in the Milky Way. Monthly Astronomical Society, 501(3), 4420-4437. <a Notices of the Royal Astronomical Society, 506(2), 1761-1776. href="http://dx.doi.org/10.1093/mnras/staa3879">[More <a href="http://dx.doi.org/10.1093/mnras/stab1086">[More Information]</a> Information]</a> Arentsen, A., Starkenburg, E., Aguado, D., Martin, N., Placco, Wiseman, P., Sullivan, M., Smith, M., Frohmaier, C., Vincenzi, V., Carlberg, R., Gonz�lez Hern�ndez, J., Hill, V., M., Graur, O., Popovic, B., Armstrong, P., Brout, D., Davis, T., Jablonka, P., Kordopatis, G., Lewis, G., Wan, Z., et al (2021). -
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. -
The Search for Living Worlds and the Connection to Our Cosmic Origins
The Search for Living Worlds and the Connection to Our Cosmic Origins Contact person: Prof Martin Barstow Address: Department of Physics & Astronomy, University of Leicester, UK Email: [email protected] Telephone: +44 116 252 3492 Imaging Earth 2.0. Simulation of the inner solar system viewed at visible wavelengths from a distance of 13 parsec with a LUVOIR telescope. The enormous glare from the central star has been suppressed with a coronagraph so the faint planets can be seen. The atmosphere of each planet can be probed with spectra to reveal its composition. Credit: L. Pueyo, M M. N’Diaye (STScI)/A. Roberge (NASA GSFC). The Search for Living Worlds – ESA Voyage 2050 White Paper Executive summary One of the most exciting scientific challenges is to detect Earth-like planets in the habitable zones of other stars in the galaxy and search for evidence of life. During the past 20 years the detection of exoplanets, orbiting stars beyond our own has moved from science fiction to science fact. From the first handful of gas giants, found through radial velocity studies, detection techniques have increased in sensitivity, finding smaller planets and diverse multi-planet systems. Through enhanced ground-based spectroscopic observations, transit detection techniques and the enormous productivity of the Kepler space mission, the number of confirmed planets has increased to more than 2000. There are several space missions, such as TESS (NASA), now operational, and PLATO (ESA), which will extend the parameter space for exoplanet discovery towards the regime of rocky earth- like planets and take the census of such bodies in the neighbourhood of the Solar System. -
Pierre Naccache Stéphane Potvin
Édition septembre 2015 « DU SAVOIR AU VÉCU » Pierre Naccache Stéphane Potvin SOMMAIRE Le mot de l’éditeur ................................................................................................ 4 Introduction ................................................................................................................. 4 Le Pierr’Eau la Lune de septembre .............................................................................. 4 Événements, nouvelles et anecdotes ................................................................... 5 Soirée de Perséides à St-Pierre .................................................................................... 5 22 août 2015, c’était le Star Party à Rimouski............................................................. 6 Le Club Cyclorizon à St-Pierre ...................................................................................... 7 Les chevaliers de St-Pierre ........................................................................................... 8 ROC 2015 ..................................................................................................................... 9 Question d’astronomie ........................................................................................ 10 Curiosity travaille sans relâche .................................................................................. 10 Capture étrange par la All Sky du COAMND .............................................................. 11 Caméra refroidie sans fil ........................................................................................... -
Science in the Urantia Papers
Science ¾ Scientific Validation of the UB z By Denver Pearson z By Phil Calabrese ¾ Seraphic Velocities ¾ Astronomy The Scientific Integrity of the Urantia Book by Denver Pearson As scientifically minded readers first peruse the Urantia Book, it soon occurs to them that many of its statements on the natural sciences conflict with currently held data and theories. In the minds of many this gives rise to doubts about the truthfulness of those statements. Wisdom would lead us to realize that nothing short of perfection is perfect, and anything touched by human hands has fingerprints. This should be our guiding thoughts as we contemplate the accuracy of the scientific content of the Urantia Papers. Several years ago, at the first scientific symposium, it was implied by one of the speakers that the revelation contains errors. This implication is alarming. More recently, at the second symposium held in Oklahoma, an interesting publication named "The Science Content of The Urantia Book" was made available (this document is obtainable from the Brotherhood of Man Library). In this publication is an article entitled "Time Bombs" in which the author suggests that the revelators planted certain inaccurate scientific statements in the book in order to prevent it from becoming a fetish. He states "...the revelators incorporated safeguards in the papers that would form The Urantia Book to diminish the tendency to regard it as an object of worship. What safeguards did they use? Suppose they decided to make sure that mortals reading it understood that some cosmological statements in the book would be found to be inaccurate". -
Next TCC Club Meeting Friday March 30 7:00 PM Dr. William Caire – Director of the Selman Living Laboratory and Observatory
Next TCC Club Meeting Friday March 30 7:00 PM Dr. William Caire – Director of the Selman Living Laboratory and Observatory Contents Presidents Message Messier Marathon March 30 Meeting One Armed Observing with a Sling Coming Events Regional Summer Astronomy Events Spring Planets March 2 Minutes Dark Sky Committee Update Treasurers report President’s Message by Ann Bruun This spring the Astronomy Club of Tulsa has been awarded a volunteer grant from Scripps Howard Foundation. The money will be used to purchase a projector and a laptop computer. With this equipment we will be able to give presentations at the observatory during public star parties and anywhere we are hosting a group interested in Astronomy. Our outreach will definitely be enhanced by this grant. The Messier Marathon is March 24 th , next Saturday, at TUVA. Be sure and read the article describing the marathon below and remember you do not have to stay all night. My first year I only made it until about 1:00 AM. You can also bring a cot to set up in the clubhouse and get some sleep. The marathon is definitely a challenge but the camaraderie is what really makes it worthwhile. Open Positions: We have two open positions I would like everyone to consider. The Group Director and the Newsletter Editor. Teresa and Jerry have each done a fantastic job in these positions respectively but unfortunately paid work has encroached and they are both having trouble finding time to fulfill their volunteer tasks the way they would like to. The Group Director is responsible for coordinating with groups that contact the club for special visits.