Author Topic: Astronomy & Planetary Science Thread  (Read 442151 times)

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #360 on: 03/08/2018 08:22 pm »
A PECULIAR GALACTIC CLASH [HEIC1805]

Quote
Galaxies are not static islands of stars – they are dynamic and ever-changing, constantly on the move through the darkness of the Universe. Sometimes, as seen in this spectacular Hubble image of Arp 256, galaxies can collide in a crash of cosmic proportions.

http://sci.esa.int/hubble/60037-a-peculiar-galactic-clash-heic1805/

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #361 on: 03/09/2018 07:20 pm »
The HR 4796A Debris System: Discovery of Extensive Exo-ring Dust Material

The optically and IR-bright and starlight-scattering HR 4796A ringlike debris disk is one of the most- (and best-) studied exoplanetary debris systems. The presence of a yet-undetected planet has been inferred (or suggested) from the narrow width and inner/outer truncation radii of its r = 1farcs05 (77 au) debris ring. We present new, highly sensitive Hubble Space Telescope (HST) visible-light images of the HR 4796A circumstellar debris system and its environment over a very wide range of stellocentric angles from 0farcs32 (23 au) to ≈15'' (1100 au). These very high-contrast images were obtained with the Space Telescope Imaging Spectrograph (STIS) using six-roll PSF template–subtracted coronagraphy suppressing the primary light of HR 4796A, with three image-plane occulters, and simultaneously subtracting the background light from its close angular proximity M2.5V companion. The resulting images unambiguously reveal the debris ring embedded within a much larger, morphologically complex, and biaxially asymmetric exo-ring scattering structure. These images at visible wavelengths are sensitive to and map the spatial distribution, brightness, and radial surface density of micron-size particles over 5 dex in surface brightness. These particles in the exo-ring environment may be unbound from the system and interacting with the local ISM. Herein, we present a new morphological and photometric view of the larger-than-prior-seen HR 4796A exoplanetary debris system with sensitivity to small particles at stellocentric distances an order of magnitude greater than has previously been observed.

http://iopscience.iop.org/article/10.3847/1538-3881/aaa3f3/pdf

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #362 on: 03/09/2018 07:42 pm »
3 NASA Satellites Recreate Solar Eruption in 3-D

The more solar observatories, the merrier: Scientists have developed new models to see how shocks associated with coronal mass ejections, or CMEs, propagate from the Sun — an effort made possible only by combining data from three NASA satellites to produce a much more robust mapping of a CME than any one could do alone.

Much the way ships form bow waves as they move through water, CMEs set off interplanetary shocks when they erupt from the Sun at extreme speeds, propelling a wave of high-energy particles. These particles can spark space weather events around Earth, endangering spacecraft and astronauts.

Understanding a shock’s structure — particularly how it develops and accelerates — is key to predicting how it might disrupt near-Earth space. But without a vast array of sensors scattered through space, these things are impossible to measure directly. Instead, scientists rely upon models that use satellite observations of the CME to simulate the ensuing shock’s behavior.



Using data from three different satellites, scientists have developed new models that recreate, in 3-D, CMEs and shocks, separately. This movie illustrates the recreation of a CME and shock that erupted from the Sun on March 7, 2011. The pink lines show the CME structure and the yellow lines show the structure of the shock - a side effect of the CME that can spark space weather events around Earth.
Credits: NASA’s Goddard Space Flight Center/GMU/APL/Joy Ng
Download this video in HD formats from NASA Goddard's Scientific Visualization Studio


The scientists — Ryun-Young Kwon, a solar physicist at George Mason University in Fairfax, Virginia, and Johns Hopkins University Applied Physics Laboratory, or APL, in Laurel, Maryland, and APL astrophysicist Angelos Vourlidas — pulled observations of two different eruptions from three spacecraft: ESA/NASA’s Solar and Heliospheric Observatory, or SOHO, and NASA’s twin Solar Terrestrial Relations Observatory, or STEREO, satellites. One CME erupted in March 2011 and the second, in February 2014.

The scientists fit the CME data to their models — one called the “croissant” model for the shape of nascent shocks, and the other the “ellipsoid” model for the shape of expanding shocks — to uncover the 3-D structure and trajectory of each CME and shock.

Each spacecraft’s observations alone weren’t sufficient to model the shocks. But with three sets of eyes on the eruption, each of them spaced nearly evenly around the Sun, the scientists could use their models to recreate a 3-D view. Their work confirmed long-held theoretical predictions of a strong shock near the CME nose and a weaker shock at the sides.

In time, shocks travel away from the Sun, and thanks to the 3-D information, the scientists could reconstruct their journey through space. The modeling helps scientists deduce important pieces of information for space weather forecasting — in this case, for the first time, the density of the plasma around the shock, in addition to the speed and strength of the energized particles. All of these factors are key to assessing the danger CMEs present to astronauts and spacecraft. Their results are summarized in a paper published in the Journal of Space Weather and Space Climate published on Feb. 13, 2018.

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #363 on: 03/13/2018 08:25 pm »
VOLCANIC WORMHOLE

Quote
The organic and intricate features of a volcanic cave come alive in great detail in this three-dimensional image of La Cueva de Los Verdes in Lanzarote, Spain. Some of the most innovative scanning technologies have produced the largest 3D scan of a lava tube on Earth.

Lava tubes are planetary caves. Similar cave systems have been found from orbit on the Moon and Mars. These underground formations could one day provide safe habitats for humans on other celestial bodies – they provide constant temperature and a good shelter against cosmic radiation and micrometeorites.

Understanding the origins and formation of these caves on Earth is a passage for simulating the future of planetary explorers across the Solar System.

A team of speleologists from the University of Padova, Italy mapped the main path of the cave system aided by ESA astronaut Matthias Mauer. The image covers a 1.3 km section of the lava tube with an unprecedented resolution of few centimetres.

http://m.esa.int/spaceinimages/Images/2018/03/Volcanic_wormhole

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #364 on: 03/15/2018 05:56 am »
We Just Caught The Strongest-Ever Fast Radio Burst, But They're Still Super Mysterious

Quote
Three more of the mysterious fast radio burst (FRB) signals have been detected this month, and one of them is a real record-breaker, coming in with the highest signal-to-noise ratio ever recorded. That makes it the "brightest" FRB that's ever been observed.


The signals came in on March 1, March 9 (that's the really bright one) and March 11, snagged by the Parkes Observatory radio telescope in remote Australia.

They are called FRB 180301, FRB 180309 and FRB 180311, following the fast radio burst convention of being named for the dates on which they occurred.

https://www.sciencealert.com/brightest-fast-radio-burst-ever-detected-parkes-observatory-frb-180309

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #365 on: 03/15/2018 07:55 pm »
New instrument built to search for Earth-like exo-planets

Quote
Yale University astronomers have developed a powerful new spectrometer to search for Earth-size planets around nearby stars. Expected to improve precision over earlier ground-based instruments by a factor of 10, the Extreme Precision Spectrometer – EXPRES – is now in operation at the Lowell Observatory’s Discovery Channel Telescope in Arizona.

https://astronomynow.com/2018/03/14/new-instrument-built-to-search-for-earth-like-exo-planets/

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #366 on: 03/15/2018 08:12 pm »

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #367 on: 03/18/2018 08:27 pm »
Thought the astronomers on here might appreciate the sentiments expressed on this Twitter thread.

https://twitter.com/AstroKatie/status/975396463625867264?s=20

Quote
This thread might be interesting if you’ve ever wondered: “Could the govt be hiding knowledge of a killer asteroid from us?” Answer is no: we’d all be talking about it on Twitter. (Thread is about worrisome object that, with more data, turned out NOT to be a threat.)

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #368 on: 03/18/2018 08:32 pm »
Didn’t want to start a new thread yet for this news.

https://twitter.com/jeff_foust/status/975410163481022464?s=20

Quote
NASA has changed its mind and will allow proposals for its next Discovery competition to use RTGs, according to an email sent late yesterday:

Offline redliox

  • Senior Member
  • *****
  • Posts: 2539
  • Illinois USA
  • Liked: 683
  • Likes Given: 97
Re: Astronomy Thread
« Reply #369 on: 03/19/2018 01:58 am »
Didn’t want to start a new thread yet for this news.

https://twitter.com/jeff_foust/status/975410163481022464?s=20

Quote
NASA has changed its mind and will allow proposals for its next Discovery competition to use RTGs, according to an email sent late yesterday:

Good news although it'd probably fit better into the Discovery or New Frontiers threads.
"Let the trails lead where they may, I will follow."
-Tigatron

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #370 on: 03/19/2018 07:32 pm »
A Changing Landscape at Ceres

Quote
Ceres turns out to be a livelier place than we might have imagined. Continuing analysis of data from the Dawn spacecraft is showing us an object where surface changes evidently caused by temperature variations induced by the dwarf planet’s orbit are readily visible even in short time frames. Two new papers on the Dawn data are now out in Science Advances, suggesting variations in the amount of surface ice as well as newly exposed crustal material.

https://www.centauri-dreams.org/2018/03/19/a-changing-landscape-at-ceres/

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #371 on: 03/20/2018 08:32 pm »
Measuring White Dwarf Masses with Gravitational Lensing

Friday, March 16, 2018

Science Update - A look at CfA discoveries from recent journals

Measuring the mass of a celestial body is one of the most challenging tasks in observational astronomy. The most successful method uses binary systems because the orbital parameters of the system depend on the two masses. In the case of black holes, neutron stars, and white dwarfs, the end states of stellar evolution, many are isolated objects, and most of them are also very faint. As a result, astronomers still do not know the distribution of their masses. They are of great interest, however, because they participate in dramatic events like the accretion of material and emission of energetic radiation, or in mergers that can result in gravitational waves, gamma-ray bursts, or Type Ia supernovae, all of which depend on an object's mass.

CfA astronomers Alexander Harding, Rosanne Di Stefano, and Claire Baker and three colleagues propose a new method for determining the masses of isolated compact objects: gravitational lensing. The path of a light beam will be bent by the presence of mass, an effect calculated by General Relativity. A massive body will act like a lens to distort the image of an object seen behind it when the two are close to being aligned along our line-of-sight, and the specifics of the image distortions will depend on the body's mass. The astronomers describe the prospects for predicting lensing events generated by nearby compact objects as their motions take them across the field of background stars.

The team estimates that the nearby population of compact objects contains about 250 neutron stars, 5 black holes, and about 35,000 white dwarf stars suitable for this study. Knowing the general motions of the white dwarfs across the sky, they obtain a statistical estimate of about 30-50 lensing events per decade that could be spotted by Hubble, ESA's Gaia mission, or NASA's new JWST telescope. The next step in this effort is to use ongoing stellar surveys like that of Gaia to refine the bodies' positions and motions to be able to predict specifically which objects to monitor for lensing.

Reference(s):
"Predicting Gravitational Lensing by Stellar Remnants," Alexander J. Harding, R. Di Stefano, S. Lepine, J. Urama, D. Pham and C. Baker, MNRAS 475, 79, 2018.

https://www.cfa.harvard.edu/news/su201811

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #372 on: 03/21/2018 08:09 pm »
K2-231 b: A sub-Neptune exoplanet transiting a solar twin in Ruprecht 147

Quote
We identify a sub-Neptune exoplanet (Rp=2.5±0.2 R⊕) transiting a solar twin in the Ruprecht 147 star cluster (3 Gyr, 300 pc, [Fe/H] = +0.1 dex). The ~81 day light curve for EPIC 219800881 (V = 12.71) from K2 Campaign 7 shows six transits with a period of 13.84 days, a depth of ~0.06%, and a duration of ~4 hours. Based on our analysis of high-resolution MIKE spectra, broadband optical and NIR photometry, the cluster parallax and interstellar reddening, and isochrone models from PARSEC, Dartmouth, and MIST, we estimate the following properties for the host star: M⋆=1.01±0.03 M⊙, R⋆=0.95±0.03 R⊙, and Teff=5695±50 K. This star appears to be single, based on our modeling of the photometry, the low radial velocity variability measured over nearly ten years, and Keck/NIRC2 adaptive optics imaging and aperture-masking interferometry. Applying a probabilistic mass-radius relation, we estimate that the mass of this planet is Mp=7+5−3 M⊕, which would cause a RV semi-amplitude of K=2±1 m s−1 that may be measurable with existing precise RV facilities. After statistically validating this planet with BLENDER, we now designate it K2-231 b, making it the second sub-stellar object to be discovered in Ruprecht 147 and the first planet; it joins the small but growing ranks of 23 other planets found in open clusters.

https://arxiv.org/abs/1803.07430

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #373 on: 03/21/2018 08:28 pm »
Evidence that a star disturbed prehistory solar system comets

Quote
About 70,000 years ago, during human occupation of the planet, a small, reddish star approached our solar system and gravitationally disturbed comets and asteroids. Astronomers from the Complutense University of Madrid and the University of Cambridge have verified that the movement of some of these objects is still marked by that stellar encounter.

Quote
Now, two astronomers from the Complutense University of Madrid, the brothers Carlos and Raúl de la Fuente Marcos, together with the researcher Sverre J. Aarseth of the University of Cambridge (United Kingdom), have analyzed for the first time nearly 340 solar system objects with hyperbolic orbits (very open V-shaped, rather than elliptical) They have concluded that the trajectories of some of these were influenced by the passage of Scholz's star.

"Using numerical simulations, we have calculated the radiants or positions in the sky from which all these hyperbolic objects seem to come," explains Carlos de la Fuente Marcos, a co-author of the study now published in Monthly Notices of the Royal Astronomical Society.

"In principle," he adds, "one would expect those positions to be evenly distributed in the sky, particularly if these objects come from the Oort cloud. However, what we find is very different—a statistically significant accumulation of radiants. The pronounced over-density appears projected in the direction of the constellation of Gemini, which fits the close encounter with Scholz's star."

I love this thought of seeing another red star so bright in the sky.

Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp


Offline as58

  • Full Member
  • ****
  • Posts: 835
  • Liked: 300
  • Likes Given: 186
Re: Astronomy Thread
« Reply #374 on: 03/21/2018 09:22 pm »
Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp

Only if human ancestors had much more sensitive eyes than we do. Even at its closest approach the star would have been fainter than 10th magnitude.

Offline CuddlyRocket


Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Astronomy Thread
« Reply #376 on: 03/22/2018 06:51 am »
Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

https://phys.org/news/2018-03-evidence-star-disturbed-prehistory-solar.amp

Only if human ancestors had much more sensitive eyes than we do. Even at its closest approach the star would have been fainter than 10th magnitude.

All the articles I’ve seen about this have reported the same thing so I assume it had come from an official press release somewhere?

Especially odd as I’ve looked into this and you’re completely correct, it’s apparent magnitude would have been 11.4 - too faint to be seen with the naked eye.
« Last Edit: 03/22/2018 06:54 am by Star One »

Offline jebbo

  • Full Member
  • ****
  • Posts: 940
  • Cambridge, UK
  • Liked: 608
  • Likes Given: 309
Re: Astronomy Thread
« Reply #377 on: 03/22/2018 07:05 am »
All the articles I’ve seen about this have reported the same thing so I assume it had come from an official press release somewhere?

I think it comes from the final line of the release from the Spanish Foundation for Science & Technology:

Quote
Scholz's star is actually a binary system formed by a small red dwarf with about 9 percent of the mass of the sun, around which a much less bright and smaller brown dwarf orbits. It is likely that human ancestors saw its faint reddish light during prehistorical nights.

Article here

It's well worth reading Eric Mamajek's FAQ for the initial discovery in 2015: here

--- Tony

Offline Bynaus

  • Full Member
  • ****
  • Posts: 562
  • Scientist, Curator, Writer, Family man
  • Switzerland
    • Final-Frontier.ch
  • Liked: 424
  • Likes Given: 316
Re: Astronomy Thread
« Reply #378 on: 03/22/2018 11:49 am »
As I read this, the only thing that might have been visible are the (potential) occasional flares.
More of my thoughts: www.final-frontier.ch (in German)

Offline Star One

  • Senior Member
  • *****
  • Posts: 13997
  • UK
  • Liked: 3974
  • Likes Given: 220
Re: Astronomy Thread
« Reply #379 on: 03/22/2018 07:56 pm »
As I read this, the only thing that might have been visible are the (potential) occasional flares.

Here’s some more thoughts on this topic

Quote
Scholz’s Star is a binary system, a red dwarf orbited by a brown dwarf, and it is likely that there was a time when our ancestors could see it in the sky. But only barely — Eric Mamajek has pointed out that even at its closest approach, the apparent magnitude would have been in the range of 11.4, which is five magnitudes fainter than what the naked eye can see, even in the pristine skies of paleolithic Earth. What might have been visible would have been flares from the M-dwarf, which could have created short-lived transient events, fleeting but noticeable.

https://www.centauri-dreams.org/2018/03/22/a-prehistoric-close-pass/

 

Advertisement NovaTech
Advertisement Northrop Grumman
Advertisement
Advertisement Margaritaville Beach Resort South Padre Island
Advertisement Brady Kenniston
Advertisement NextSpaceflight
Advertisement Nathan Barker Photography
1