Author Topic: Astronomy Thread  (Read 87063 times)

Offline CuddlyRocket

Re: Astronomy Thread
« Reply #520 on: 08/01/2018 06:50 AM »
Revised Radii of Kepler Stars and Planets using Gaia Data Release 2 (arXiv)

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(Abstract)
One bottleneck for the exploitation of data from the Kepler mission for stellar astrophysics and exoplanet research has been the lack of precise radii and evolutionary states for most of the observed stars. We report revised radii of 177,911 Kepler stars derived by combining parallaxes from Gaia Data Release 2 with the DR25 Kepler Stellar Properties Catalog. The median radius precision is ≈ 8%, a typical improvement by a factor of 4-5 over previous estimates for typical Kepler stars. We find that ≈ 67% (≈ 120,000) of all Kepler targets are main-sequence stars, ≈ 21% (≈ 37,000) are subgiants, and ≈ 12% (≈ 21,000) are red giants, demonstrating that subgiant contamination is less severe than some previous estimates and that Kepler targets are mostly main-sequence stars. Using the revised stellar radii, we recalculate the radii for 2123 confirmed and 1922 candidate exoplanets. We confirm the presence of a gap in the radius distribution of small, close-in planets, but find that the gap is mostly limited to incident fluxes > 200F⊕ and its location may be at a slightly larger radius (closer to ≈ 2R⊕) when compared to previous results. Further, we find several confirmed exoplanets occupying a previously-described "hot super-Earth desert" at high irradiance, show the relation between gas-giant planet radius and incident flux, and establish a bona-fide sample of eight confirmed planets and 30 planet candidates with Rp < 2R⊕ in circumstellar "habitable zones" (incident fluxes between 0.25--1.50 F⊕). The results presented here demonstrate the potential for transformative characterization of stellar and exoplanet populations using Gaia data.

Offline Star One

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Re: Astronomy Thread
« Reply #521 on: 08/01/2018 08:11 PM »
New radio telescope picks up mysterious signal from space

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The observatory in Canada may have already found clues to one of the newest mysteries in astronomy.

https://www.cnet.com/google-amp/news/new-radio-telescope-picks-up-mysterious-signal-from-space/

Offline Star One

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Re: Astronomy Thread
« Reply #522 on: 08/03/2018 08:25 PM »
New facility to simulate conditions on Venus

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The German Space Agency (DLR) has opened a new simulation facility at its Planetary Spectroscopy Laboratory (PSL) in Berlin. The facility could help researchers better understand the surface of Venus hidden behind the planet's dense atmosphere.

https://phys.org/news/2018-08-facility-simulate-conditions-venus.amp

Scientists identify exoplanets where life could develop as it did on Earth

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Scientists have identified a group of planets outside our solar system where the same chemical conditions that may have led to life on Earth exist.

The researchers, from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology (MRC LMB), found that the chances for life to develop on the surface of a rocky planet like Earth are connected to the type and strength of light given off by its host star.

Their study, published in the journal Science Advances, proposes that stars which give off sufficient ultraviolet (UV) light could kick-start life on their orbiting planets in the same way it likely developed on Earth, where the UV light powers a series of chemical reactions that produce the building blocks of life.

https://www.eurekalert.org/pub_releases/2018-08/uoc-sie073018.php

Offline Star One

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Re: Astronomy Thread
« Reply #523 on: 08/03/2018 08:35 PM »
Probing Oort clouds around Milky Way stars with CMB surveys

Long-period comets observed in our solar system are believed to originate from the Oort cloud, which is estimated to extend from roughly a few thousand to 105 AU from the Sun. Despite many theoretical arguments for its existence, no direct observations of the cloud have been reported. Here, we explore the possibility of measuring Oort clouds around other stars through their emission at submillimeter wavelengths. Observations with the 545 and 857 GHz bands of the Planck satellite are well matched to the expected temperatures of Oort cloud bodies (on the order of 10 K). By correlating the Planck maps with catalogs of stars observed by the Gaia mission, we are able to constrain interesting regions of the exo-Oort cloud parameter space, placing limits on the total mass and the minimum size of grains in the cloud. We also explore an observed excess around the brightest and nearest stars in our sample as arising from possible exo-Oort clouds or other extended sources of thermal emission. We compare our measurements with known debris disk systems -- in the case of Vega and Fomalhaut we find a significant excess that is in agreement with measurements from Herschel. We use the measurements around Fomalhaut to constrain a possible exo-Oort cloud of that system. We argue that future CMB surveys and targeted observations with far-infrared and millimeter wavelength telescopes have the potential to detect exo-Oort clouds or other extended sources of thermal emission beyond ∼1000 AU from the parent stars.

https://arxiv.org/abs/1808.00415

Habitability in the Omega Centauri Cluster

The search for exoplanets has encompassed a broad range of stellar environments, from single stars in the solar neighborhood to multiple stars and various open clusters. The stellar environment has a profound effect on planet formation and stability evolution and is thus a key component of exoplanetary studies. Dense stellar environments, such as those found in globular clusters, provide particularly strong constraints on sustainability of habitable planetary conditions. Here, we use Hubble Space Telescope observations of the core of the Omega Centauri cluster to derive fundamental parameters for the core stars. These parameters are used to calculate the extent of the Habitable Zone of the observed stars. We describe the distribution of Habitable Zones in the cluster and compare them with the stellar density and expected stellar encounter rate and cluster dynamics. We thus determine the effect of the stellar environment within the Omega Centauri core on the habitability of planets that reside within the cluster. Our results show that the distribution of Habitable Zone outer boundaries generally lie within 0.5 AU of the host stars, but that this small cross-sectional area is counter-balanced by a relatively high rate of stellar close encounters that would disrupt planetary orbits within the Habitable Zone of typical Omega Centauri stars.

https://arxiv.org/abs/1808.00053

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Re: Astronomy Thread
« Reply #524 on: 08/08/2018 07:54 PM »
Largest haul of extrasolar planets for Japan

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Forty-four planets in solar systems beyond our own have been unveiled in one go, dwarfing the usual number of confirmations from extrasolar surveys, which is typically a dozen or less. The findings will improve our models of solar systems and may help researchers investigate exoplanet atmospheres. Novel techniques developed to validate the find could hugely accelerate the confirmation of more extrasolar planet candidates.

An international team of astronomers pooled data from U.S. space agency NASA's Kepler and the European Space Agency (ESA)'s Gaia space telescopes, as well as ground-based telescopes in the U.S. Alongside John Livingston, lead author of the study and a graduate student at the University of Tokyo, the team's combined resources led to the confirmed existence of these 44 exoplanets and described various details about them.

https://www.eurekalert.org/pub_releases/2018-08/uot-lho080718.php

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Re: Astronomy Thread
« Reply #525 on: 08/09/2018 08:41 PM »
Planetary-Mass Magnetic Powerhouse

Object is at boundary between giant planet and brown dwarf

https://public.nrao.edu/news/planetary-mass-powerhouse/

Offline Star One

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Re: Astronomy Thread
« Reply #526 on: 08/14/2018 05:02 PM »
MSU astronomers discovered supermassive black hole in an ultracompact dwarf galaxy

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Fornax UCD3 is a part of a Fornax galaxy cluster and belongs to a very rare and unusual class of galaxies - ultracompact dwarfs. The mass of such dwarf galaxies reaches several dozen millions of solar masses and the radius, typically, does not exceed three hundred light years. This ratio between mass and size makes UCDs the densest stellar systems in the Universe.

"We have discovered a supermassive black hole in the center of Fornax UCD3. The black hole mass is 3.5 million that of the Sun, similar to the central black hole in our own Milky Way" explained Anton Afanasiev, the first author of the article, a student of the department of the Faculty of Physics, MSU.

https://www.eurekalert.org/pub_releases/2018-08/lmsu-mad081318.php

Offline Star One

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Re: Astronomy Thread
« Reply #527 on: 08/14/2018 08:27 PM »
The Venus controversy

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A lack of new missions keeps scientists guessing on what shaped the planet’s surface

http://www.planetary.org/blogs/guest-blogs/the-venus-controversy.html

Offline Star One

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Re: Astronomy Thread
« Reply #528 on: 08/14/2018 08:38 PM »
Excavation Begins on Giant Magellan Telescope Site in Chile
Release No.:
2018-16
For Release:
Tuesday, August 14, 2018 - 11:00am
GMT hard rock excavation
Cambridge, MA -
GMTO Corporation (GMTO) today announced the start of hard rock excavation for the Giant Magellan Telescope's massive concrete pier and the foundations for the telescope's enclosure on its site at Las Campanas Observatory in Chile. The work will be performed by Minería y Montajes Conpax (known as Conpax), a construction services company that has previously performed site work for other observatories in Chile. Using a combination of hydraulic drilling and hammering, the excavation work is expected to take about five months to complete. Excavation is a key step towards the construction of the GMT, which is expected to see first light as early as 2024.

The 25-meter diameter GMT, expected to have a final weight of about 1,600 metric tons, will comprise seven 8.4-meter mirrors supported by a steel telescope structure that will be seated on the concrete pier. It will be housed inside a rotating enclosure that will measure 65 meters (~22 stories) tall and 56 meters wide. As well as working on the enclosure and telescope pier foundations, Conpax will excavate a recess in the summit rock for the lower portion of the mirror coating chamber and foundations for a utility building and tunnel on the summit.

GMTO Project Manager, Dr. James Fanson, said, "With the start of construction of the permanent buildings on the site, the GMT is showing tangible progress towards completion. We are delighted that Conpax is carrying out this important work."

The most challenging part of their work on the summit will be to excavate the solid rock of the mountain top to a depth of 7 meters (23 feet) to hold the concrete for the telescope pier. Much of this work will be done with a hydraulic rock hammer and jack hammer to ensure that the integrity of the solid bedrock below the pier is undamaged. Dr. Fanson said, "In total, we expect to remove 5,000 cubic meters or 13,300 tons of rock from the mountain and will need 330 dump truck loads to remove it from the summit."

Las Campanas Observatory, located in the southern Atacama Desert of Chile and owned by the Carnegie Institution for Science, is one of the world's premier astronomical sites, known for its clear, dark skies and stable airflow, producing exceptionally sharp images. With its unique design, the GMT will produce images that are 10 times sharper than those from the Hubble Space Telescope in the infrared region of the spectrum and will be used by astronomers to study planets around other stars and to look back to the time when the first galaxies formed.

In the past year, the GMT project has cast the fifth primary mirror segment at the Richard F. Caris Mirror Lab at the University of Arizona, announced a new partner for the project with Arizona State University, and awarded design-build contracts for the telescope mount.

This release is being issued jointly with GMTO.

The 2018 Science Book describing GMT's strengths and its potential for scientific discovery was recently released and is available for download.

GMTO Corporation (GMTO) manages the Giant Magellan Telescope project on behalf of its U.S. and international partners: Arizona State University, Astronomy Australia Ltd., The Australian National University, Carnegie Institution for Science, Fundação de Amparo à Pesquisa do Estado de São Paulo, Harvard University, Korea Astronomy and Space Science Institute, Smithsonian Institution, Texas A&M University, The University of Texas at Austin, University of Arizona, and University of Chicago.

The Smithsonian Astrophysical Observatory (SAO) leads the team responsible for the spectrograph G-CLEF (GMTConsortium Large Earth Finder). G-CLEF, when mounted on the GMT, will significantly advance the detection and characterization of planets around other stars. It is designed to detect the presence of diatomic oxygen in the atmospheres of Earth-like planets orbiting nearby stars. Terrestrial O2 is produced by living organisms. The search for life on other planets is one of the key programs of the Harvard University Origins of Life Initiative, with senior members from both Harvard College Observatory and SAO. The GMT will also enable important progress in a broad range of other fields of astrophysics, including understanding how galaxies form and evolve, and advancing the exciting new field of gravitational wave astronomy.

The Harvard-Smithsonian Center for Astrophysics also participates in the GMT through active membership on the GMTO Board and the Science Advisory Committee, as well as leadership in technical design reviews. SAO scientists have also played a leading role in designing the mirror alignment system.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a collaboration between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. CfA scientists, organized into six research divisions, study the origin, evolution and ultimate fate of the universe.

Offline Star One

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Re: Astronomy Thread
« Reply #529 on: 08/15/2018 08:56 PM »
Iron and titanium in the atmosphere of an exoplanet

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Exoplanets, planets in other solar systems, can orbit very close to their host stars. When the host star is much hotter than the sun, the exoplanet becomes as hot as a star. The hottest "ultra-hot" planet was discovered last year by American astronomers. Today, an international team led by researchers from the University of Geneva (UNIGE), who collaborated with theoreticians from the University of Bern (UNIBE), Switzerland, discovered the presence of iron and titanium vapours in the atmosphere of this planet. The detection of these heavy metals was made possible by the surface temperature of the planet, which reaches more than 4000 degrees. This discovery is published in the journal Nature.

https://m.phys.org/news/2018-08-iron-titanium-atmosphere-exoplanet.html

Offline Star One

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Re: Astronomy Thread
« Reply #530 on: 08/17/2018 07:05 AM »
Earliest galaxies found 'on our cosmic doorstep'

https://www.bbc.co.uk/news/science-environment-45198764

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Astronomy Thread
« Reply #531 on: 08/18/2018 08:31 AM »
Surely a major boost for the likelihood of extraterrestrial life. Might explain the Fermi Paradox if the universe is full of intelligent marine life. Guess Douglas Adams was right.

Water-worlds are common: Exoplanets may contain vast amounts of water

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Scientists have shown that water is likely to be a major component of those exoplanets (planets orbiting other stars) which are between two to four times the size of Earth. It will have implications for the search of life in our Galaxy. The work is presented at the Goldschmidt Conference in Boston.

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Li Zeng continued, "Our data indicate that about 35% of all known exoplanets which are bigger than Earth should be water-rich. These water worlds likely formed in similar ways to the giant planet cores (Jupiter, Saturn, Uranus, Neptune) which we find in our own solar system. The newly-launched TESS mission will find many more of them, with the help of ground-based spectroscopic follow-up. The next generation space telescope, the James Webb Space Telescope, will hopefully characterize the atmosphere of some of them. This is an exciting time for those interested in these remote worlds".

https://m.phys.org/news/2018-08-water-worlds-common-exoplanets-vast-amounts.html
« Last Edit: 08/18/2018 08:41 AM by Star One »