HR 8799 is a 6th magnitude spectral class A5V star, about 129 light-years away in Pegasus, measuring 1.56 solar masses and 1.5 solar radii. The star is known to host four planets, which are up to 10 times more massive than Jupiter, but only slighly larger.
Based on eight observations of the planets over 7 years since 2009, the image sequence taken at the W.M. Keck observatory in Hawaii indicates that the four planets are orbiting in a one-two-four-eight resonance with each other.
As a result of their huge masses the planets are orbiting far away from each other. The innermost, e, average distance to the star is 14.5 AU, while the outermost, b, is 68 AU away, which is more than twice the Sun-to-Pluto distance, the period out there being about 450 years for one orbit.
The black circle in the center blocks the blinding light of the star which is about 5 times brighter than the Sun, and thus make the planets visible.
Jason Wang and Christian Marois
Posted on 2017-04-18
Since March 2017, one of the closest stars to our sun is known to have at least two planets, the Luyten's Star in Canis Minor at a distance of 12.2 light-years and about 1.2 light-years away from Procyon, the primary star of the small constellation. Also designated GJ 273, Luyten's outer planet b has 2.89 terran masses and orbits barely inside the habitable zone in 18.65 days but receives solar energy equivalent to that of Earth from the sun. Presence of an protectve atmosphere provided life could have evolved.
The inner planet c outside the HBZ has 1.18 terran masses, orbits the star in 4.72 days and heat scorched, a so-called hot terran planet because its orbit lies between the HBZ and the star.
Both planets are moving on eccentric orbit suggesting seasonal changes and that neither is tidally locked.
Luyten's Star is a cool, red class M star about a third of the size and the mass of the sun, rotating slowly in about 120 days around its axis. As a 10th magnitude star is way beyond bare eye visibility.
Posted on 2017-03-22
Named for the small telescope located in Chile searching for planets around nearby stars, TRAPPIST-1, also registered as 2MASS J23062928-0502285, is a 2550°K 'cool', dim class M8 red dwarf star barely larger than Jupiter, approximately 8% the mass and 11% the radius of the Sun.
TRAPPIST-1 is located 39.5 light-years away in the constellation of Aquarius and, since Feruary 2017, known to host at least seven near-earth-sized rocky planets detected by transit, all orbiting closer to the star than Mercury to the Sun, in that they are probably tidally locked and exposed to strong radiation and flares.
The planetary system is extremely dense. The closest distance between TRAPPIST-1b and TRAPPIST-1c is merely 1.6 lunar distances. The planets should appear prominently in each others skies some larger than our Moon. The light on the surfaces at noon should be no brighter than twilight on earth. Three of the planets orbit within the star's habitable zone, the others close to it.
Orbit view: NASA/JPL-Caltech
Surface: ESO/N. Bartmann/spaceengine.org
Posted on 2017-02-23
Astronomers announced a planet around 'Proxima Centauri'. Proxima is the smallest in a system of three stars, located in the constellation of Centaurus, only 4.22 light-years away.
The planet is a bit larger than Earth and 1.3 times as massive but orbits around Proxima in merely 11.2 days at a distance of 7.5 million km which is closer than Mercury in our solar system. Although positioned within the habitable zone, the planet is most probably tidally locked and under strong radiation exposure (X-ray and ultraviolet) by its parent which is a red dwarf flare star 12% the mass of our sun and merely about 1.4 times wider than Jupiter.
The unnamed planet appears to be rocky and might be warm enough (up to + 30°C) to host liquid water, and thus be habitable, however, on the star faced side only, and if it has an atmosphere and magnetic field to shield itself. It resembles an 'eyeball planet whose day side is sun-baked and dry while the permanent night side is covered with ice. In between lies a thin ring that may sustain forms of life. Details regarding the true circumstances are still speculation.
Image credit: Hubble Space Telescope
Posted on 2016-08-25
Pr 0211 is one of the stars in the Beehieve Cluster (Praesepe) or Messier 44 some 580 light-years away. It is the first star in an open cluster around which multiple planets have been detected, 2 planets as of today. Because of the high star density in this cluster (over 1000) an observer there would admire a truly starry sky and probably seeing more than 2 planets.The innermost planet, Pr 0211 b, about twice as massive than Jupiter is a Hot Jovian, so close to the star in that it orbits it in just 2.15 days under scorching heat.The outer planet, Pr 0211c, is 8 times as massive as Jupiter is a Cold Jovian with a 5300 days orbital period at a mean distance of 5.8 AU. The highly eccentric orbit of Pr 0211c could be caused by disruption of the planetary system from close encounters with passing stars in the dense open cluster.Pr 0211 is a variable spectral class G9 star with 94% solar mass and 83% solar radius. Given its distance and luminosity, it is invisible to the unaided eye.Since it is reasonable to assume that stars in a cluster share same or similar age and metallicity, mass and age can be determined at higher precision as compared with field stars. A star cluster is afavorable environment for measuring physical properties of stars and their planets and how they are related.
Posted on 2016-03-31
Wolf 1061 (HIP 80824 and V2306 Ophiuchi) is an M3V-class red dwarf high proper motion star (-21km/s) located about 14 light years away in the constellation Ophiuchus. It is the 36th closest star system to the Sun and, as of December 17th., 2015, known to host 3 planets while the second is well located in the inner edge of habitable zone which extends from approximately 0.075 to 0.19 AU off the 3380°K cool star, merely 26% as wide and 25% as massive as the Sun. The planets were detected by analyzing 10 years of observations of the Wolf 1061 system by the HARPS spectrograph at La Silla Observatory in Chile.
|Name||Mass [xE]||Radius [xE]||SMA [AU]||Period [d]|
|Wolf 1061 b||1.36||1.45||0.036||4.888|
|Wolf 1061 c||4.25||1.65||0.084||17.87|
|Wolf 1061 d||5.21||2.05||0.204||67.27|
Image credit: Requio, Okinawa.
Posted on 2015-12-19
As of October 17, 2005, the star cataloged HD 219134 (or HR 8832, HIP 114622, Gliese 892) is officially known to host at least 7 planets. It is located some 21 light-years away in Cassiopeia and, as a 5th magnitude star, can be seen with bare eyes.
|Planet||Mass [xE]||Radius [xE]||SMA [AU]||Period [d]|
Image credit: Requio Web Design, mouse activated images: NASA/JPL Caltech
Posted on 2015-10-18
51 Eridani is a 5th magnitude, yellow-white main sequence star of spectral type F0V, just visible to the unaided eye, situated some 96 light-years away in the constellation of Eridanus. A cold disk of debris has been detected around the star with an inner border of 82AU. In December 2014, a young jovian planet has been photographed and announced in August 2015. A team of astronomers have used the Gemini Observatory's new Gemini Planet Imager to find the most solar system-like planet ever directly imaged around another star.
The planet, dubbed 51 Eridani b, is about twice the mass of Jupiter and orbits its host star at about 13.2 AUs (equivalent to being between Saturn and Uranus in our solar system). Its average temperature is 650°C. The Gemini data provide scientists with the strongest-ever spectroscopic detection of methane and water in the atmosphere of an extrasolar planet, adding to its similarities to giant planets in our solar system.
Image credit: J. Rameau (UdeM) and C. Marois (NRC Herzberg).
Posted on 2015-08-26
Analysis of earlier Kepler Telescope observations unveiled a planet around a sun-like star at a distance of some 1400 light-years out in the constellation of Cygnus.Compared with the Earth, the planet, dubbed Kepler 452 b, is 60% larger with 2x the surface gravity, and similarly to Earth, rotates around its parent once in 385 days at a mean distance of slightly over 1 AU -- the average Sun-Earth distance. It's mass is unknown but could range between 3~7 terran, probably rocky. With large uncertainty, though, the star Kepler-452 is 6 billion years old, 1.5 billion years older than our sun, giving that much more time for life to have evolved there, if any present. It has the same effective temperature, but is 20% brighter, and 10% wider. Prior to this discovery, the 'record holder' for the most "Earth-like" planet went to Kepler-186f / Kepler-62f, which are 10% / 40% larger than Earth both orbiting within the HBZ.
Image credit: NASA/Ames/JPL-Caltech
Posted on 2015-07-24
Published on July 15, 2015, an international group of astronomers has used the ESO 3.6-metre telescope to identify a planet just like Jupiter orbiting at the same distance from a Sun-like star, HIP 11915. The existence of a Jovian-mass planet in a Jupiter-like orbit around a Sun-like star opens the possibility that the system of planets around this star may be similar to our own Solar System. HIP 11915 is about the same age as the Sun and, furthermore, its Sun-like composition suggests that there may also be rocky planets orbiting closer to the star.
With a 0.99 jovian mass, HIP 11915 b orbits its host star in 10.5 years at a mean distance of 4.8AU close to that of Jupiter in our solar system.The G-class star lies 187 light-years away in Cetus shining at 8.58 magnitudes (visible in binoculars). The sun as seen from HIP 11915 has asimilar apparent magnitude located in the constellation of Boötes near Arcturus.
Image credit: Requio Web Design
Posted on 2015-07-23
The gap between the inner edge of Saturn's rings and the top of Saturn's atmosphere is about 1,500 miles (2,000 kilometers) wide.
On April 26, 2017, while NASA's spacecraft Cassini dove through the unexplored region, it came within about 1,900 miles (3,000 kilometers) of Saturn's cloud tops without any damage through particles. This was the first of 22 scheduled passages. Before diving into the gap Cassini passed over the north pole returning images of a hexagon-shape cloud formation partly with a resolution of 1 km per pixel.
During this final chapter, Cassini loops Saturn approximately once per week, making a total of 22 dives between the rings and the planet. No spacecraft has ever been this close to Saturn before.
Cassini is on a trajectory that will eventually plunge into Saturn's atmosphere on Sep 15, 2017.
NASA/JPL-Caltech/SSI/Kevin M. Gill
Posted on 2017-05-05
NASA's Dawn mission has found evidence for organic material on Ceres, mainly located in an area covering approximately 1000 square km. The signature of organics is very clear on the floor of Ernutet Crater, on its southern rim and in an area just outside the crater to the southwest. Another large area with well-defined signatures is found across the northwest part of the crater rim and ejecta. There are other smaller organic-rich areas several kilometers west and east of the crater. Organics also were found in a very small area in Inamahari Crater, about 400 km away from Ernutet.
The organics discovery adds to Ceres' attributes associated with ingredients and conditions for life in the distant past. Previous studies have found hydrated minerals, carbonates, water ice, and ammoniated clays that must have been altered by water. Salts and sodium carbonate, such as those found in the bright areas of Occator Crater, are also thought to have been carried to the surface by liquid. Ceres shares many commonalities with meteorites rich in water and organics - in particular, a meteorite group called carbonaceous chondrites.
Posted on 2017-02-17
NASA's Hubble Space Telescope has captured one of the sharpest, most detailed observations of a comet breaking apart. In a series of images taken over a three-day span in January 2016, Hubble revealed 25 building-size blocks made of a mixture of ice and dust that are drifting away from the comet named 332P/Ikeya-Murakami.
The enlarged image shows the slow migration of building-size fragments of Comet 332P/Ikeya-Murakami which broke off of the main nucleus in late 2015 as the icy comet approached the sun in its orbit.
The observations suggest that the roughly 4.5-billion-year-old comet may be spinning so fast that material is ejected from its surface and provide insight into the volatile behavior of comets as they approach the sun and begin to vaporize, unleashing dynamical forces. The resulting debris is now scattered along a 5,000-km-long trail.
Comet 332P was discovered in November 2010, after it surged in brightness and was spotted by two Japanese amateur astronomers, Kaoru Ikeya and Shigeki Murakami.
Image credits: NASA, ESA, D. Jewitt (UCLA)
Posted on 2017-01-21
NASA has chartered and geocached the entire surface of our smaller neighbor Mars thanks to its thin atmosphere and low air pressure, unlike Venus which is enshrouded in a toxic atmosphere with high air pressure and a lead-melting ground temperature.
Nevertheless, already on March 1st, 1980 Venera 13, a Soviet spacecraft landed on the southern hemisphere of Venus at 7.5°S, 303°E with a parachute and sent back data for more than two hours - including the best close-up images to date, the first in color. The lander also discovered leucite basalt in a soil sample using a spectrometer.
From a series of 16 Verena probes developed between 1961 and 1984 seven landed softly on Venus' surface followed by three further landings of Vega probes which were basic Venera design.
Text RWD, images: NASA/Venera Project
Posted on 2017-01-16
Images from NASA's Dawn spacecraft have revealed a dark, heavily cratered world whose brightest area is made of highly reflective salts -- not ice, however, newly published studies show two distinct lines of evidence for ice at or near the surface of the dwarf planet.
The image compares the hydrogen content of Ceres' upper meter of regolith, the loose surface material, with that of the giant asteroid Vesta, which Dawn orbited from 2011 to 2012. These data show Vesta is a much drier world, with a much lower percent of hydrogen in its regolith. In reality, some of the hydrogen is in the form of water ice, while a portion of the hydrogen is in the form of hydrated minerals (such as OH, in serpentine group minerals).
Ceres' uppermost surface is rich in hydrogen, with higher concentrations at mid-to-high latitudes -- consistent with broad expanses of water ice which is important because it is an essential ingredient for life as we know it.
Posted on 2016-12-16
The first-ever views of Jupiter's pole regions were taken by NASA's Juno spacecraft on August 27, 2016 from a distance of 125,000 km (north pole) and 94,500km (south pole) above the planet during its orbital flyby.
In absence of characteristical latitudinal bands there are numerous clockwise and counterclockwise rotating storms of various sizes while higher altitude clouds appear to cast shadows.
The Juno spacecraft launched on Aug. 5, 2011, from Cape Canaveral, Florida, and arrived at Jupiter on July 4, 2016. Juno executed the first of 36 orbital flybys on August 27 when the spacecraft came about 4,200 km above Jupiter.
Juno, the first spacecraft to carry a titanium vault designed to shield its computer and electronics from intense radiation, will also probe how the planet's intense magnetic field is generated, and examine the formation of auroras.
Posted on 2016-11-27
NASA's Cassini spacecraft captured prominent long cloud streaks that lie between 49 and 55 degrees north latitude on Saturn' largest moon Titan, on Oct. 29 and 30, 2016. These clouds are measured to move at a speed of about 14 to 22 miles per hour (7 to 10 meters per second).In 2016, Cassini has intermittently observed clouds across the northern mid-latitudes of Titan, as well as within the north polar region -- an area known to contain numerous methane/ethane lakes and seas. Models of Titan's climate have predicted more cloud activity during early northern summer than what Cassini has observed so far, suggesting that the current understanding of the giant moon's changing seasons is incomplete. The mission will continue monitoring Titan's weather around the 2017 summer solstice in Titan's northern hemisphere.
NASA/JPL-Caltech/Space Science Institute
Posted on 2016-11-23
In April 2016, NASA's New Horizons spacecraft observed 1994 JR1, a 90-mile (145-kilometer) wide Kuiper Belt object orbiting more than 3 billion miles (5 billion kilometers) from the sun, for the second time. Taken on April 7-8 from a distance of about 69 million miles (111 million km), the images shatter New Horizons' own record for the closest-ever views of this KBO in November 2015, when New Horizons detected JR1 from 170 million miles (280 million km) away.
Combining the November 2015 and April 2016 observations allows scientists to pinpoint the location of JR1 to within 1,000 km (about 600 miles), far better than any small KBO. The more accurate orbit also allows the science team to dispel a theory that JR1 is a quasi-satellite of Pluto.
From the closer vantage point of the April 2016 observations, the team also determined the object's rotation period, observing the changes in light reflected from JR1's surface to determine that it rotates once every 5.4 hours. Its period is 247.53 years on a stable orbit entirely beyond Neptune.
The observations are great practice for possible close-up looks at about 20 more ancient Kuiper Belt objects that may come in the next few years.
Posted on 2016-10-04
New Horizons recently observed the Kuiper Belt object Quaoar, which is roughly half the size of Pluto. This animated sequence shows composite images taken by New Horizons' Long Range Reconnaissance Imager (LORRI) at four different times over July 13-14: "A" on July 13 at 02:00 Universal Time; "B" on July 13 at 04:08 UT; "C" on July 14 at 00:06 UT; and "D" on July 14 at 02:18 UT.
When these images were taken, Quaoar was approximately 6.4 billion kilometers from the sun and 2.1 billion km from New Horizons. The images also captured two far away galaxies, IC 1048 and UGC 09485.
A year on Quaoar is about 286 terran years orbiting at a mean distance of 43 AU. Rotating in 17.68 hours, it is the densest known KBO and has a moon, Weywot, 74 km wide orbiting at a distance of 14,500 km.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute
Posted on 2016-09-01
After discovering dwarf planet Makemake in 2005, astronomers had searched several times for a companion orbiting the icy world. End of April 2015, the Hubble Space Telescope has uncovered a tiny moon around Makemake, at that time in Coma Berenices, that is estimated to be 160 km wide and some 21,000 km away from the dwarf planet. Provisionally designated S/2015 (136472) 1 and nicknamed MK 2, the moon is more than 1,300 times fainter than Makemake, which is 1400 km across.
Uncovering the moon also reinforces the idea that most dwarf planets have satellites. By measuring the moon's orbit, astronomers can calculate a mass for the system and gain insight into its evolution. Preliminary estimates indicate that if the moon is in a circular orbit, it completes a circuit around Makemake in 12 days or longer.
Credit: NASA, ESA, A. Parker and M. Buie (Southwest Research Institute), W. Grundy (Lowell Observatory), and K. Noll (NASA GSFC)
Posted on 2016-04-26
On the 1,228th Martian day, or sol, NASA's Curiosity Mars Rover operating on the surface of Mars, took this mosaic image on January 19, 2016, combining 57 frames using its onboard Mars Hand Lens Imager (MAHLI). The photo shows uriosity at "Namib Dune," where the rover's is scuffing into the dune with a wheel and scooping samples of sand for laboratory analysis. Namib Dune is situated along the northwestern flank of Mount Sharp. Images taken from orbit have shown that dunes in the Bagnold field move as much as about 3 feet (1 meter) per Earth year.
For scale, the rover's wheels are 20 inches (50 centimeters) in diameter and about 16 inches (40 centimeters) wide. The size of the image published by NASA spans 10519 x 11225 pixels on a 16.4 MB data footprint.
Posted on 2016-01-29
A 'planet Nine' without visual proof but mathematically modeledby Caltech astronomer, Mike Brown and planetary scientist Konstantin Batygin, as the team found that dwarf planet Sedna and similarly classified bodies orbit under gravitational influence caused by a pertubing body at least 10 times the mass of Earth, and about 20 times further out than Neptune on a some 20,000-years trip around the sun.
Its current orbit position is not known, in that telescopes cannot just be pointedat the object. At this extreme distance from the sun, the object maybe 600 times fainter than Pluto. The primary search now conducted with the Japanese Subaru Telescope on Mauna Kea is expected to take up to 5 years.
Stay tuned as further news check in.
Illustration: Requio Web Design
Orbit Plot: K. Batgyn and M. E. Brown
Posted on 2016-01-21
Scheduled for launch in October 2018 on an Ariane 5 rocket from French Guaina, the James Webb Telescope, JWST, is an optical reflecting telescope with a 6.5 meter mirror (clear aperture of 25m²), composed of 18 hexagonal segments made from rigid, light-weight beryllium. The mirror of the Hubble Space Telescope is 2.4 meters across. Also onboard, a Science Instrument Module and the spacecraft element including the spacecraft bus and sunshield, as well as a suite of infrared cameras as eyes.
To achieve a single perfect focus, the primary mirror segments and secondary mirror are moved by six actuators attached to the back of each mirror piece. The primary mirror segments also have an additional actuator at its center that adjusts its curvature. In order to align the primary mirror segments as though they form a single large mirror, each mirror segment is aligned to 1/10,000th. the thickness of a human hair!
The mission of the JWST is searching for the first galaxies after the Big Bang, determine how galaxies evolved, observe the formation of stars and planetary systems, measure properties of planetary systems, and investigate the potential for life. JWST will orbit the sun, a million miles away from Earth at the second Lagrange point (four lunar distances).
3D Tour (NASA)
Images courtesy NASA Goddard Space Flight Center
Posted on 2016-03-15
WFIRST, Wide Field Infrared Survey Telescope, is a NASA space observatory designed to explore dark energy, exoplanets, and infrared astrophysics, performing wide-field imaging and surveys of the near infrared sky.
The telescope has a primary mirror that is 2.4 meters in diameter (7.9 feet), the same size as the Hubble Space Telescope's primary mirror, but has a 100 times wider field of view, that is, it can image the Andromeda galaxy with only 2 pointings, saving observation time at the same high resolution.
WFIRST will carry a coronagraph enabling astronomers to detect and measure properties of exoplanets and study their atmospheres.
The telescope's sensitivity and wide view will enable a large-scale search for exoplanets by monitoring the brightness of millions of stars in the crowded central region of our galaxy. The survey will net thousands of new exoplanets complementing NASA's Kepler mission and the upcoming Transiting Exoplanet Survey Satellite.
Images courtesy NASA/GSFC/Conceptual Image Lab
Posted on 2016-02-20
Objects that have mass ripple surrounding space generate gravitational waves, propagating at light speed, that bend space and time the more the larger the mass, just like a stone thrown into a lake. Published on February 12, 2016 in Washington DC, gravitational waves have been measured and confirmed by the US-based LIGO Observatory on Sep 14, 2015, by capturing the signature of two merging black holes.
For instance, black holes with an incredible mass cannot be seen because they swallow light, but gravitational waves they generate unveil their existence. Likewise, binary or multiple star systems comprising large masses, orbiting and rotating at high velocity, generate gravitational waves, thus ripples in spacetime.
Albert Einstein predicted gravitational waves 100 years before in June 1916, but did not believe to find evidence because the effect is extremely minute. The compression effect measured by LIGO is 1/1000th the size of a hydrogen atom.
Illustrations Courtesy Caltech/MIT/LIGO Laboratory
Posted on 2016-02-12