Hubble and Gaia measure Cepheid variable stars: Using two of the world’s most powerful space telescopes — the NASA/ESA Hubble Space Telescope and ESA’s Gaia — astronomers have made the most precise measurements to date of the Universe’s expansion rate. This is calculated by gauging the distances between nearby galaxies using special types of stars called Cepheid variables as cosmic yardsticks. By comparing their intrinsic brightness — measured with Hubble — with their apparent brightness as seen from Earth, scientists can calculate their distances. Gaia further refines this yardstick by measuring the distances to Cepheid variables within our Milky Way Galaxy using astrometry. This allowed astronomers to more precisely calibrate the distances to Cepheids that are seen in other galaxies.

Type: Local Universe : StarLocal Universe : Galaxy
Category: Stars
Release date: 16 July 2018, 11:43
Credit: NASA, ESA, and A. Feild (STScI)

Artist's impression of disc around a neutron star: This illustration shows a neutron star (RX J0806.4-4123) with a disc of warm dust that produces an infrared signature as detected by the NASA/ESA Hubble Space Telescope. The disc was not directly images, but one way to explain the data is by hypothesising a disc structure that could be 29 billion kilometres across. The disc would be made up of material falling back onto the neutron star after the supernova explosion that created the stellar remnant.

Name: RX J0806.4-4123
Type: Milky Way : Star : Evolutionary Stage : Neutron Star
Category: Stars
Release date: 18 September 2018, 11:09
Credit: NASA, ESA, and N. Tr’Ehnl (Pennsylvania State University)

Artist's impression of pulsar wind from a neutron star: This is an illustration of a pulsar wind nebula produced by the interaction of the outflow particles from the neutron star with gaseous material in the interstellar medium that the neutron star is plowing through. Such an infrared-only pulsar wind nebula is unusual because it implies a rather low energy of the particles accelerated by the pulsar’s intense magnetic field. This hypothesised model would explain the unusual infrared signature of the neutron star RX J0806.4-4123 as detected by the NASA/ESA Hubble Space Telescope.

Name: RX J0806.4-4123
Type: Milky Way : Star : Evolutionary Stage : Neutron Star
Category: IllustrationsStars
Release date: 18 September 2018, 11:09
Credit: NASA, ESA, and N. Tr’Ehnl (Pennsylvania State University)

Hubble sees an unusual neutron star: This is a near-infrared-light image of the neutron star RX J0806.4-4123 taken with the NASA/ESA Hubble Space Telescope. Hubble detected an unusual excess of infrared radiation that might be evidence for a disc around the stellar remnant. Or it could be from a wind of charged particles streaming off the neutron star and slamming into gas in the interstellar medium the neutron star is plowing through.

Name: RX J0806.4-4123
Type: Milky Way : Star : Evolutionary Stage : Neutron Star
Category: Stars
Release date: 18 September 2018, 11:09
Credit: NASA, ESA, and B. Posselt (Pennsylvania State University)

Artist's illustration of a young red dwarf stripping away a planet's atmosphere: Violent outbursts of seething gas from young red dwarf stars may make conditions uninhabitable on fledgling planets. In this artist's rendering, an active, young, red dwarf (right) is stripping the atmosphere from an orbiting planet (left). Scientists found that flares from the youngest red dwarfs they surveyed — approximately 40 million years old — are 100 to 1000 times more energetic than when the stars are older. They also detected one of the most intense stellar flares ever observed in ultraviolet light — more energetic than the most powerful flare ever recorded from our Sun.

Type: Unspecified : Star
Category: Stars
Release date: 19 October 2018, 14:57
Credit: NASA, ESA, and D. Player (STScI)

Artist's impression of progenitor star to a type Ic supernova: This is an artist's impression of a blue supergiant star that once existed inside a cluster of young stars in the spiral galaxy NGC 3938, located 65 million light-years away. It exploded as a supernova in 2017, and NASA/ESA Hubble Space Telescope archival photos were used to locate the doomed progenitor star, as it looked in 2007. The star may have been 50 as massive as our Sun and burned at a furious rate, making it hotter and bluer than our Sun. It was so hot, it had lost its outer layers of hydrogen and helium. When it exploded in 2017, astronomers categorised it as a Type Ic supernova because of the lack of hydrogen and helium in the supernova's spectrum. In an alternative scenario (not shown here) a binary companion to the massive star may have stripped off its hydrogen and helium layers.

Name: SN 2017ein
Type: Local Universe : Star : Evolutionary Stage : Supernova
Category: Stars
Distance: 65 million light years
Release date: 16 November 2018, 13:53
Credit: NASA, ESA, and J. Olmsted (STScI)

Astronomers find a supernova's progenitor star in Hubble images: This NASA/ESA Hubble Space Telescope image of the nearby spiral galaxy NGC 3938 shows the location of supernova 2017ein, in a spiral arm near the bright core. The exploded star is a Type Ic supernova, thought to detonate after its massive star has shed or been stripped of its outer layers of hydrogen and helium. Progenitor stars to Type Ic supernovas have been hard to find. But astronomers sifting through Hubble archival images may have uncovered the star that detonated as supernova 2017ein. The location of the candidate progenitor star is shown in the pullout box at bottom left, taken in 2007. The bright object in the box at bottom right is a close-up image of the supernova, taken by Hubble in 2017, shortly after the stellar blast. NGC 3938 resides 65 million light-years away in the constellation Ursa Major (the Great Bear). The Hubble image of NGC 3938 was taken in 2007.

Name: NGC 3938, SN 2017ein
Type: Local Universe : Star : Evolutionary Stage : SupernovaEarly Universe : Galaxy : Type : Spiral
Category: GalaxiesStars
Distance: 65 million light years
Release date: 16 November 2018, 13:53
Credit: NASA, ESA, S. Van Dyk (Caltech), and W. Li (University of California)

Artist's impression of gas streaming from GJ 3470b: This artist's impression shows a giant cloud of hydrogen streaming off a warm, Neptune-sized planet just 97 light-years from Earth. The exoplanet is tiny compared to its star, a red dwarf named GJ 3470. The star's intense radiation is heating the hydrogen in the planet's upper atmosphere to a point where it escapes into space. The alien world is losing hydrogen at a rate 100 times faster than a previously observed warm Neptune whose atmosphere is also evaporating away.

Name: Gliese 3470b
Type: Milky Way : Planet
Category: Exoplanets
Distance: 97 light years
Release date: 17 December 2018, 15:51
Credit: NASA, ESA, and D. Player (STScI)

Exoplanet radius versus distance from star: This graphic plots exoplanets based on their size and distance from their star. Each dot represents an exoplanet. Planets the size of Jupiter (located at the top of the graphic) and planets the size of Earth and so-called super-Earths (at the bottom) are found both close to and far from their star. But planets the size of Neptune (in the middle of the plot) are scarce close to their star. This so-called desert of hot Neptunes shows that such alien worlds are rare, or, they were plentiful at one time, but have since disappeared. The detection that GJ 3470b, a warm Neptune at the border of the desert, is fast losing its atmosphere suggests that hotter Neptunes may have eroded down to smaller, rocky super-Earths.

Name: Gliese 3470b
Type: Milky Way : Planet
Category: Exoplanets
Distance: 95 light years
Release date: 17 December 2018, 15:51
Credit: NASA, ESA, and A. Feild (STScI)