Category Archives: Astronomy

Thethys, the Spy

Тефия и Рея

Tethys appears to be peeking out from behind Rhea, watching the watcher.

Scientists believe that Tethys’ surprisingly high albedo is due to the water ice jets emerging from its neighbor, Enceladus. The fresh water ice becomes the E ring and can eventually arrive at Tethys, giving it a fresh surface layer of clean ice.

Lit terrain seen here is on the anti-Saturn side of Rhea. North on Rhea is up. The image was taken in red light with the Cassini spacecraft narrow-angle camera on April 20, 2012.

The view was obtained at a distance of approximately 1.1 million miles (1.8 million kilometers) from Rhea and at a Sun-Rhea-spacecraft, or phase, angle of 59 degrees. Image scale is 7 miles (11 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov or http://www.nasa.gov/cassini. The Cassini imaging team homepage is athttp://ciclops.org .

Credit: NASA/JPL-Caltech/Space Science Institute

Sun and solar activity 02.12.2014

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INFO FROM SIDC – RWC BELGIUM 2014 Dec 02 11:50:40 Solar activity is low. The strongest flare, out of 5 low-level C-class flares reported in the last 24 hours, was the impulsive C5.2 flare (peaking at 08:05 UT) on December 2. The flare originated from the Catania sunspot group 18 (NOAA AR 2217), and does not seem to be associated with CME (currently available data give no indication about possible on disc signatures of the CME). Catania sunspot groups 18 and 24 (NOAA ARs 2217 and 2222) maintain beta-gamma configuration of their photospheric magnetic field and could be the source of C-class flares. An isolated M-class flare is still possible from the Catania sunspot group 24 (NOAA AR 2222). No Earth directed CMEs were observed during last 24 hours.The Earth is currently inside a fast solar wind with the speed of about 550 km/s. This high speed stream which arrived on the midday of December 01, is associated with the extended low-latitude coronal hole (between N25 and N70) which reached the central meridian on the morning of November 26 (the transition of the coronal hole across the central meridian lasted more than two days). During last 24 hours the interplanetary magnetic field was slightly elevated, reaching the magnitude of about 12nT, but its current value decrease to about 5nT. The arrival of the coronal hole high speed stream resulted in the unsettled to active geomagnetic conditions (K=3 reported by Dourbes, K=4 reported by IZMIRAN and NOAA reported Kp=4) in the evening of December 1 and early morning of December 2. The geomagnetic conditions are at the moment quiet to unsettled and expected to remain so in the coming hours.

Sun online and solar activity 01.12.2014

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INFO FROM SIDC – RWC BELGIUM 2014 Dec 01 12:33:26 Several low-level C-class flares and one M-class flare were reported during last 24 hours. A long duration M1.8 flare, observed this morning, peaked at 06:41 UT. The M-class flare, as well as few C-class flares, originated from the Catania sunspot group 24 (NOAA AR 2222) which maintains beta-gamma configuration of its photospheric magnetic field. Currently available data give no indication about possible on disc signatures of the associated CME, therefore, we conclude that the M1.8 flare was most probably confined flare. Four out of ten currently numbered sunspot groups visible on the solar disc have beta-gamma configuration of their photospheric magnetic field and could be the source of the C-class flares and possible also an isolated M-class flare in the coming hours. No Earth directed CMEs were observed during last 24 hours.The Earth is currently inside a slow solar wind, with the speed of about 430 km/s. The interplanetary magnetic field is stable with the magnitude of about 5nT. The geomagnetic conditions are at the moment quiet to unsettled and expected to remain so in the following hours.

Sun online and solar activity 26.11.2014

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INFO FROM SIDC – RWC BELGIUM 2014 Nov 26 12:25:23 Four C-class flare were observed, with NOAA 2217 producing the strongest event of the period (C2.9 peaking at 06:17UT). Slowly developing region NOAA 2219 and a new, currently unnumbered, region near the east limb merit some attention, as they were the sources of the other C-class flares. Numerous, but quiet, filaments are present on the solar disk, with the longest measuring 40 degrees and located in the NE quadrant. No Earth-directed CMEs were observed. Further C-class flaring is expected, with a small chance on an isolated M-class flare. Solar wind speed declined from about 400 to 320 km/s. Bz was mostly negative and varied between -6 and +4 nT. The IMF is directed away from the Sun. The geomagnetic field was quiet to unsettled (K<4), and is expected to remain so. Effects from an expected Sector Boundary Crossing and the possible high speed stream from the extension of a coronal hole may result in an isolated active period on 27-28 November.

Sun online and solar activity 24.11.2014

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INFO FROM SIDC – RWC BELGIUM 2014 Nov 24 12:16:19

Five low-level C-class flares were observed over the last 24 hours. The largest was a C4.1 peaking at 11:04UT in NOAA 2217, which was also the source of 3 other C2 flares. One of these peaked on 23 November at 16:14UT and was associated to a non-Earth directed CME, first visible in LASCO at 16:24UT. NOAA 2216 produced the remaining C2 flare. The other regions were quiet, with NOAA 2209 still maintaining a weak delta spot in its trailing portion. More C-class flares are expected, with a chance on an isolated M-class flare. The IMF is directed away from the Sun, with Bz varying between -7 and +4 nT. Solar wind speed varied between 470 and 360 km/s and is currently near 400 km/s. The geomagnetic field was quiet to unsettled (K<3), and is expected to remain so, with an isolated active period possible.

The Sun online and Solar Activity 23.11.2014

UPH20141124091421 INFO FROM SIDC – RWC BELGIUM 2014 Nov 23 12:43:20 NOAA ARs 2209 and 2216 (Catania numbers 9 and 14 respectively) have delta-spots in their trailing parts and continue to produce C-class flares. However, the strongest flare of the past 24 hours was the C3.5 flare peaking at 10:53 UT today in the still unnumbered sunspot group that appeared from behind the east solar limb yesterday evening. We expect flaring activity on the C-level, possibly with an isolated M-class flare. A long filament in the northern hemisphere has finished crossing the solar central meridian, but its eruption may still lead to an Earth-directed CME.The Earth is currently inside a slow (around 400 km/s) solar wind flow with slightly elevated (7-8 nT) interplanetary magnetic field magnitude. Due to low solar wind speed, the geomagnetic conditions remained mostly at the quiet to unsettled level (K < 4), only with one interval of active conditions (K = 4) reported by IZMIRAN and NOAA yesterday evening. The geomagnetic conditions are expected to stay at the quiet to unsettled levels (K < 4), with isolated intervals of active conditions (K = 4).

Dumbbell Nebula

63507ccf115a0f7cc008b082aeaa7de6.1824x0_q100_watermark_watermark_opacity-10_watermark_position-1_watermark_text-Copyright ray.gilman@cox.net

 

The Dumbbell Nebula (also known as Apple Core Nebula, Messier 27, M 27, or NGC 6853) is a planetary nebula in the constellationVulpecula, at a distance of about 1,360 light years.

This object was the first planetary nebula to be discovered; by Charles Messier in 1764. At its brightness of visual magnitude 7.5 and its diameter of about 8 arcminutes, it is easily visible in binoculars, and a popular observing target in amateur telescopes.

The Dumbbell Nebula appears to be shaped like an prolate spheroid and is viewed from our perspective along the plane of its equator. In 1992, Moreno-Corral et al. computed that its rate of expansion in the plane of the sky was no more than 2.3″ per century. From this, an upper limit to the age of 14,600 yr may be determined. In 1970, Bohuski, Smith, and Weedman found an expansion velocity of 31 km/s. Given its semi-minor axis radius of 1.01 ly, this implies that the kinematic age of the nebula is some 9,800 years.

Like many nearby planetary nebulae, the Dumbbell contains knots. Its central region is marked by a pattern of dark and bright cusped knots and their associated dark tails (see picture). The knots vary in appearance from symmetric objects with tails to rather irregular tail-less objects. Similarly to the Helix Nebula and the Eskimo Nebula, the heads of the knots have bright cusps which are local photoionizationfronts.

Imaging telescopes or lenses: Meade LX200 12″ GPS Pier mount
Imaging cameras: QSI 640 WSG-8
Mounts: Meade LX200 fork mount standard fork mount
Guiding telescopes or lenses: Borg 101ED/F6.4
Guiding cameras: SBIG STi-C
Focal reducers: Starizona SCT Corrector f/7.5
Software: Cyanogen Maxim DL5, Software Bisque TheSky
Filters: Astronomik Ha 12nm, Asronomik OIII , Astronomic SII 12nm
Accessories: Shoestring Astronomy FCUSB, Focuser JMI EVN-2
Resolution: 2048×2048
Dates: Oct. 1, 2014
Locations: Home Observatory
Frames: 33×300″
Integration: 2.8 hours
Avg. Moon age: 6.54 days
Avg. Moon phase: 41.10%
RA center: 299.901 degrees
DEC center: 22.708 degrees
Pixel scale: 0.722 arcsec/pixel
Orientation: -10.793 degrees
Field radius: 0.291 degrees

Autor: Ray G, 04.10.2014

47 Tucanae (NGC 104)

47 Tucanae (NGC 104) or just 47 Tuc is a globular cluster located in the constellation Tucana. It is about 16,700 light years away from Earth, and 120 light years across. It can be seen with the naked eye, with a visual apparent magnitude of 4.9. Its number comes not from the Flamsteedcatalogue, but the more obscure 1801 “Allgemeine Beschreibung und Nachweisung der Gestirne nebst Verzeichniss” compiled by Johann Elert Bode.

47 Tucanae was discovered by Nicolas Louis de Lacaille in 1751, who thought it was the nucleus of a bright comet. Its southern location had hidden it from European observers until then. The cluster appears roughly the size of the full moon in the sky under ideal conditions.

It is the second brightest globular cluster in the sky (after Omega Centauri), and is noted for having a very bright and dense core. It is also one of the most massive globular clusters in the Galaxy, containing millions of stars.

The core of 47 Tuc was the subject of a major survey for planets, using the Hubble Space Telescope to look for partial eclipses of stars by their planets. No planets were found, though 10-15 were expected based on the rate of planet discoveries around stars near the Sun. This indicates that planets are relatively rare in globular clusters. A later ground-based survey in the uncrowded outer regions of the cluster also failed to detect planets when several were expected. This strongly indicates that the low metallicity of the environment, rather than the crowding, is responsible.

47 Tuc’s dense core contains a number of exotic stars of scientific interest. Globular clusters efficiently sort stars by mass, with the most massive stars falling to the center. 47 Tuc contains at least 21 blue stragglers near its core. It also contains hundreds of X-ray sources, including stars with enhanced chromospheric activity due to their presence in binary star systems, cataclysmic variable stars containing white dwarfs accreting from companion stars, and low-mass X-ray binaries containing neutron stars that are not currently accreting, but can be observed by the X-raysemitted from the hot surface of the neutron star. 47 Tuc has 23 known millisecond pulsars, the second largest population of pulsars in any globular cluster. These pulsars are thought to be spun up by the accretion of material from binary companion stars, in a previous X-ray binaryphase. The companion of one pulsar in 47 Tucanae, 47 Tuc W, seems to still be transferring mass towards the neutron star, indicating that this system is completing a transition from being an accreting low-mass X-ray binary to a millisecond pulsar. X-ray emission has been individually detected from most millisecond pulsars in 47 Tuc with the Chandra X-ray Observatory, likely emission from the neutron star surface, and gamma-ray emission has been detected with the Fermi Gamma-ray Space Telescope from its millisecond pulsar population (making 47 Tuc the first globular cluster to be detected in gamma-rays).

There is no evidence yet for the existence of any black holes in 47 Tuc; Hubble Space Telescope data provides the strongest constraint on the mass of any possible black hole at its center, < 1500 times the mass of our Sun.

In December 2008, Ragbir Bhathal of the University of Western Sydney claimed the detection of a strong laser-like signal from the direction of 47 Tucanae.

How to Identify that Light in the Sky 

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Image Credit & Copyright: HK (The League of Lost Causes)

 What is that light in the sky? Perhaps one of humanity’s more common questions, an answer may result from a few quick observations. For example – is it moving or blinking? If so, and if you live near a city, the answer is typically an airplane, since planes are so numerous and so few stars and satellites are bright enough to be seen over the din of artificial city lights. If not, and if you live far from a city, that bright light is likely a planet such as Venus or Mars – the former of which is constrained to appear near the horizon just before dawn or after dusk. Sometimes the low apparent motion of a distant airplane near the horizon makes it hard to tell from a bright planet, but even this can usually be discerned by the plane’s motion over a few minutes. Still unsure? The above chart gives a sometimes-humorous but mostly-accurate assessment. Dedicated sky enthusiasts will likely note – and are encouraged to provide – polite corrections.

NASA APOD 09-Jun-14

NGC 5584

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NGC 5584
The brilliant, blue glow of young stars traces the graceful spiral arms of galaxy NGC 5584. Among the galaxy’s myriad stars are pulsating stars called Cepheid variables and one recent Type Ia supernova, a special class of exploding stars. Astronomers use Cepheid variables and Type Ia supernovae as reliable distance markers to measure the universe’s expansion rate. NGC 5584 was one of eight galaxies astronomers studied to measure the universe’s expansion rate.