Monday, January 23, 2017

You Are in Command as NRAO's 'Orion Explorer' Tours this Iconic Constellation

How can you travel to distant stars from the comfort of your own home? It's easy with the new Orion Explorer, the latest installment in NRAO's interactive Milky Way Explorer. Credit: NRAO/AUI/NSF


Imagine an up-close view of a red supergiant star, a peek inside a glowing nebula churning out new stars, and spying a myriad of other objects in our galaxy as you have never seen them before – in invisible radio light! That is the experience you will get through the National Radio Astronomy Observatory’s (NRAO) newly released Orion Explorer installment of its popular Milky Way Explorer, an online tour of our interstellar neighborhood guided by the actual astronomers who study it using radio waves.

Through an entertaining and informative series of videos, NRAO’s Science Visualization Team presents multimedia-rich tours of the stars Bellatrix and Betelgeuse, stellar masers, snowlines around young stars, and much more. At each stop along the way, astronomers reveal the new science and exciting details we have learned about one of the most recognizable star patterns in the night sky, the constellation of Orion.

Unlike familiar optical telescopes, which can only study objects illuminated by stars, radio telescopes can see the otherwise invisible cold, dark features in space. This includes the faint radio light that is naturally emitted by the molecules and chemicals that make up vast interstellar clouds where new stars are born, like the Orion Nebula.

The Milky Way Explorer, which was launched in 2013, also includes dozens more videos showcasing the diverse radio astronomy studies of our home galaxy and its environs.


The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.


For more information, contact:

Alexandra Angelich
aangelic@nrao.edu



Friday, January 20, 2017

A slice of Sagittarius

Constelation of Sagittarius (The Archer)
 Credit: ESA/Hubble & NASA


This stunning image, captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), shows part of the sky in the constellation of Sagittarius (The Archer). The region is rendered in exquisite detail — deep red and bright blue stars are scattered across the frame, set against a background of thousands of more distant stars and galaxies. Two features are particularly striking: the colours of the stars, and the dramatic crosses that burst from the centres of the brightest bodies.

While some of the colours in this frame have been enhanced and tweaked during the process of creating the image from the observational data, different stars do indeed glow in different colours. Stars differ in colour according to their surface temperature: very hot stars are blue or white, while cooler stars are redder. They may be cooler because they are smaller, or because they are very old and have entered the red giant phase, when an old star expands and cools dramatically as its core collapses. 

The crosses are nothing to do with the stars themselves, and, because Hubble orbits above Earth’s atmosphere, nor are they due to any kind of atmospheric disturbance. They are actually known as diffraction spikes, and are caused by the structure of the telescope itself. Like all big modern telescopes, Hubble uses mirrors to capture light and form images. Its secondary mirror is supported by struts, called telescope spiders, arranged in a cross formation, and they diffract the incoming light. Diffraction is the slight bending of light as it passes near the edge of an object. Every cross in this image is due to a single set of struts within Hubble itself! Whilst the spikes are technically an inaccuracy, many astrophotographers choose to emphasise and celebrate them as a beautiful feature of their images.



Thursday, January 19, 2017

Public to Choose Jupiter Picture Sites for NASA Juno

This amateur-processed image was taken on Dec. 11, 2016, at 9:27 a.m. PST (12:27 p.m. EST), as NASA's Juno spacecraft performed its third close flyby of Jupiter. Credit: Image credit: NASA/JPL-Caltech/SwRI/MSSS/Eric Jorgensen.  › Full image and caption


Where should NASA's Juno spacecraft aim its camera during its next close pass of Jupiter on Feb. 2? You can now play a part in the decision. For the first time, members of the public can vote to participate in selecting all pictures to be taken of Jupiter during a Juno flyby. Voting begins Thursday, Jan. 19 at 11 a.m. PST (2 p.m. EST) and concludes on Jan. 23 at 9 a.m. PST (noon EST).

"We are looking forward to people visiting our website and becoming part of the JunoCam imaging team," said Candy Hansen, Juno co-investigator from the Planetary Science Institute, Tucson, Arizona. "It's up to the public to determine the best locations in Jupiter's atmosphere for JunoCam to capture during this flyby."

NASA's JunoCam website can be visited at: https://www.missionjuno.swri.edu/junocam

The voting page for this flyby is available at:https://www.missionjuno.swri.edu/junocam/voting/

JunoCam will begin taking pictures as the spacecraft approaches Jupiter's north pole. Two hours later, the imaging will conclude as the spacecraft completes its close flyby, departing from below the gas giant's south pole. Juno is currently on its fourth orbit around Jupiter. It takes 53 days for Juno to complete one orbit.

"The pictures JunoCam can take depict a narrow swath of territory the spacecraft flies over, so the points of interest imaged can provide a great amount of detail," said Hansen. "They play a vital role in helping the Juno science team establish what is going on in Jupiter's atmosphere at any moment. We are looking forward to seeing what people from outside the science team think is important."

There will be a new voting page for each upcoming flyby of the mission. On each of the pages, several points of interest will be highlighted that are known to come within the JunoCam field of view during the next close approach. Each participant will get a limited number of votes per orbit to devote to the points of interest he or she wants imaged. After the flyby is complete, the raw images will be posted to the JunoCam website, where the public can perform its own processing.

"It is great to be able to share excitement and science from the Juno mission with the public in this way," said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. "Amateur scientists, artists, students and whole classrooms are providing the world with their unique perspectives of Jupiter. I am really pleased that this website is having such a big impact and allowing so many people to join the Juno science team. The public involvement is really affecting how we look at the most massive planetary inhabitant in our solar system."

During the Feb. 2 flyby, Juno will make its closest approach to Jupiter at 4:58 a.m. PST (7:58 a.m. EST), when the spacecraft is about 2,700 miles (4,300 kilometers) above the planet's swirling clouds.
JunoCam is a color, visible-light camera designed to capture remarkable pictures of Jupiter's poles and cloud tops. As Juno's eyes, it will provide a wide view of Jupiter over the course of the mission, helping to provide context for the spacecraft's other instruments. JunoCam was included on the spacecraft primarily for public engagement purposes, although its images also are helpful to the science team.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of Southwest Research Institute in San Antonio. The Juno mission is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama, for NASA's Science Mission Directorate. Lockheed Martin Space Systems, Denver, built the spacecraft. JPL is a division of Caltech in Pasadena, California.


More information on the Juno mission is available at: http://www.nasa.gov/juno -  http://www.missionjuno.swri.edu


The public can follow the mission on Facebook and Twitter at: http://www.facebook.com/NASAJuno  -  http://www.twitter.com/NASAJuno


News Media Contact

DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@jpl.nasa.gov

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown@nasa.gov / laura.l.cantillo@nasa.gov


Source:  JPL-Caltech

Galaxy murder mistery

Spiral galaxy NGC 4921
This artist’s impression shows the spiral galaxy NGC 4921 based on observations made by the Hubble Space Telescope. 
Credit: ICRAR, NASA, ESA, the Hubble Heritage Team (STScI/AURA).

Ram-pressure stripping of galaxy NGC 4921 
An artist’s impression of ram-pressure stripping of galaxy NGC 4921. Stripping removes gas—the raw fuel for star formation—and could be the dominant way galaxies are killed by their environment. Credit: ICRAR, NASA, ESA, the Hubble Heritage Team (STScI/AURA).

Ram-pressure stripping removing gas from galaxies
An artist’s impression showing the increasing effect of ram-pressure stripping in removing gas from galaxies, sending them to an early death. Credit: ICRAR, NASA, ESA, the Hubble Heritage Team (STScI/AURA)


Ram Stripping of Galaxies
An animation showing how ram-pressure stripping removes gas from galaxies, sending them to an early death. 
Credit: ICRAR, NASA, ESA, the Hubble Heritage Team (STScI/AURA)



It’s the big astrophysical whodunnit. Across the Universe, galaxies are being killed and the question scientists want answered is, what’s killing them?

New research published today by a global team of researchers, based at the International Centre for Radio Astronomy Research (ICRAR), seeks to answer that question. The study reveals that a phenomenon called ram-pressure stripping is more prevalent than previously thought, driving gas from galaxies and sending them to an early death by depriving them of the material to make new stars.

The study of 11,000 galaxies shows their gas—the lifeblood for star formation—is being violently stripped away on a widespread scale throughout the local Universe.

Toby Brown, leader of the study and PhD candidate at ICRAR and Swinburne University of Technology, said the image we paint as astronomers is that galaxies are embedded in clouds of dark matter that we call dark matter halos.

Dark matter is the mysterious material that despite being invisible accounts for roughly 27 per cent of our Universe, while ordinary matter makes up just 5 per cent. The remaining 68 per cent is dark energy.

“During their lifetimes, galaxies can inhabit halos of different sizes, ranging from masses typical of our own Milky Way to halos thousands of times more massive,” Mr Brown said.

“As galaxies fall through these larger halos, the superheated intergalactic plasma between them removes their gas in a fast-acting process called ram-pressure stripping.

“You can think of it like a giant cosmic broom that comes through and physically sweeps the gas from the galaxies.” Mr Brown said removing the gas from galaxies leaves them unable to form new stars.

“It dictates the life of the galaxy because the existing stars will cool off and grow old,” he said.

“If you remove the fuel for star formation then you effectively kill the galaxy and turn it into a dead object.” ICRAR researcher Dr Barbara Catinella, co-author of the study, said astronomers already knew ram-pressure stripping affected galaxies in clusters, which are the most massive halos found in the Universe.

“This paper demonstrates that the same process is operating in much smaller groups of just a few galaxies together with much less dark matter,” said Mr. Brown. “Most galaxies in the Universe live in these groups of between two and a hundred galaxies,” he said.

“We’ve found this removal of gas by stripping is potentially the dominant way galaxies are quenched by their surrounds, meaning their gas is removed and star formation shuts down.”

The study was published in the journal Monthly Notices of the Royal Astronomical Society. It used an innovative technique combining the largest optical galaxy survey ever completed—the Sloan Digital Sky Survey—with the largest set of radio observations for atomic gas in galaxies —the Arecibo Legacy Fast ALFA survey.

Mr Brown said the other main process by which galaxies run out of gas and die is known as strangulation.

“Strangulation occurs when the gas is consumed to make stars faster than it’s being replenished, so the galaxy starves to death,” he said. “It’s a slow-acting process. On the contrary, what ram-pressure stripping does is bop the galaxy on the head and remove its gas very quickly—of the order of tens of millions of years—and astronomically speaking that’s very fast.”



Publications Details


‘Cold gas stripping in satellite galaxies: from pairs to clusters’, published in the Monthly Notices of the Royal Astronomical Society on January 17th, 2017.

Click here for the research paper



More Information

ICRAR

The International Centre for Radio Astronomy Research (ICRAR) is a joint venture between Curtin University and The University of Western Australia with support and funding from the State Government of Western Australia.



Contact Information

Mr Toby Brown (ICRAR-UWA, Swinburne University of Technology)
Email:
toby.brown@icrar.org
M: +61 6488 7753
 
Dr Barbara Catinella (ICRAR-UWA)
Email:
barbara.catinella@icrar.org
Tel: +972 89346511
 
Pete Wheeler—Media Contact, ICRAR
Email:
pete.wheeler@icrar.org
M: +61 423 982 018


Wednesday, January 18, 2017

Geminga and B0355+54: Chandra Images Show That Geometry Solves a Pulsar Puzzle

Geminga and  PSR B0355+54
Credit: X-ray: NASA/CXC/PSU/B.Posselt et al; 
Infrared: NASA/JPL-Caltech; Illustration: Nahks TrEhnl




NASA's Chandra X-ray Observatory has taken deep exposures of two nearby energetic pulsars flying through the Milky Way galaxy. The shape of their X-ray emission suggests there is a geometrical explanation for puzzling differences in behavior shown by some pulsars.

Pulsars - rapidly rotating, highly magnetized, neutron stars born in supernova explosions triggered by the collapse of massive stars were discovered 50 years ago via their pulsed, highly regular, radio emission. Pulsars produce a lighthouse-like beam of radiation that astronomers detect as pulses as the pulsar's rotation sweeps the beam across the sky.

Since their discovery, thousands of pulsars have been discovered, many of which produce beams of radio waves and gamma rays. Some pulsars show only radio pulses and others show only gamma-ray pulses. Chandra observations have revealed steady X-ray emission from extensive clouds of high-energy particles, called pulsar wind nebulas, associated with both types of pulsars. New Chandra data on pulsar wind nebulas may explain the presence or absence of radio and gamma-ray pulses.

This four-panel graphic shows the two pulsars observed by Chandra. Geminga is in the upper left and B0355+54 is in the upper right. In both of these images, Chandra's X-rays, colored blue and purple, are combined with infrared data from NASA's Spitzer Space Telescope that shows stars in the field of view. Below each data image, an artist's illustration depicts more details of what astronomers think the structure of each pulsar wind nebula looks like.

For Geminga, a deep Chandra observation totaling nearly eight days over several years was analyzed to show sweeping, arced trails spanning half a light year and a narrow structure directly behind the pulsar. A five-day Chandra observation of the second pulsar, B0355+54, showed a cap of emission followed by a narrow double trail extending almost five light years.

The underlying pulsars are quite similar, both rotating about five times per second and both aged about half a million years. However, Geminga shows gamma-ray pulses with no bright radio emission, while B0355+54 is one of the brightest radio pulsars known yet not seen in gamma rays.

A likely interpretation of the Chandra images is that the long narrow trails to the side of Geminga and the double tail of B0355+54 represent narrow jets emanating from the pulsar's spin poles. Both pulsars also contain a torus, a disk-shaped region of emission spreading from the pulsar's spin equator. These donut-shaped structures and jets are crushed and swept back as the pulsars fly through the Galaxy at supersonic speeds.

In the case of Geminga, the view of the torus is close to edge-on, while the jets point out to the sides. B0355+54 has a similar structure, but with the torus viewed nearly face-on and the jets pointing nearly directly towards and away from Earth. In B0355+54, the swept-back jets appear to lie almost on top of each other, giving a doubled tail.

Both pulsars have magnetic poles quite close to their spin poles, as is the case for the Earth's magnetic field. These magnetic poles are the site of pulsar radio emission so astronomers expect the radio beams to point in a similar direction as the jets. By contrast the gamma-ray emission is mainly produced along the spin equator and so aligns with the torus.

For Geminga, astronomers view the bright gamma-ray pulses along the edge of the torus, but the radio beams near the jets point off to the sides and remain unseen. For B0355+54, a jet points almost along our line of sight towards the pulsar. This means astronomers see the bright radio pulses, while the torus and its associated gamma-ray emission are directed in a perpendicular direction to our line of sight, missing the Earth.

These two deep Chandra images have, therefore, exposed the spin orientation of these pulsars, helping to explain the presence, and absence, of the radio and gamma-ray pulses.
The Chandra observations of Geminga and B0355+54 are part of a large campaign, led by Roger Romani of Stanford University, to study six pulsars that have been seen to emit gamma-rays. The survey sample covers a range of ages, spin-down properties and expected inclinations, making it a powerful test of pulsar emission models.

A paper on Geminga led by Bettina Posselt of Penn State University was accepted for publication in The Astrophysical Journal and is available online. A paper on B0355+54 led by Noel Klingler of the George Washington University was published in the December 20th, 2016 issue of The Astrophysical Journal and is available online. NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.



Fast Facts for Geminga:

Scale: Image is 4.6 arcmin across. (About 1 light year)
Category: Neutron Stars/X-ray Binaries
Coordinates (J2000): RA 06h 33m 54.15s | Dec Dec: +17 46 12.91
Constellation: Gemini
Observation Dates: 14 pointings between Feb 2004 and Sep 2013
Observation Time: 188 hours 21 min
Obs. IDs: 4674, 7592, 14691-14694, 15551, 15552, 15595, 15622, 15623, 16318, 16319, 16372
Instrument: ACIS
References: Posselt, B. et al, 2016, ApJ (accepted); arXiv:1611.03496
Color Code: X-ray (Pink, Blue); Infrared (Grayscale)
Distance Estimate: About 800 light years



Fast Facts for PSR B0355+54:

Scale: Image is 1.8 arcmin across. (About 1.8 light years)
Category: Neutron Stars/X-ray Binaries
Coordinates (J2000): RA 03h 58m 53.72s | Dec Dec: +54 13 13.73
Constellation: Camelopardalis
Observation Dates: 8 pointings between Nov 2012 and July 2013
Observation Time: 109 hours 45 min
Obs. IDs: 14688-14690, 15548-15550, 15585, 15586
Instrument:
ACIS
Color Code: X-ray (Pink, Blue); Infrared (Grayscale)
Distance Estimate: About 3400 light years 



Tuesday, January 17, 2017

ALMA Starts Observing the Sun

ALMA observes a giant sunspot (1.25 millimetres)

ALMA observes a giant sunspot (3 millimetres)

ALMA observes the full solar disc

Image of the solar surface alongside a close-up view of a sunspot from ALMA



Videos

ESOcast 92 Light: ALMA Starts Observing the Sun
ESOcast 92 Light: ALMA Starts Observing the Sun

Comparison of the solar disc in ultraviolet and millimetre wavelength light
Comparison of the solar disc in ultraviolet and millimetre wavelength light

Sunspot seen in visible and millimetre wavelength light
Sunspot seen in visible and millimetre wavelength light



Image Comparison

Comparison of the solar disc in ultraviolet and millimetre wavelength light

Comparison of the solar disc in ultraviolet and millimetre wavelength light



New images taken with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile have revealed otherwise invisible details of our Sun, including a new view of the dark, contorted centre of a sunspot that is nearly twice the diameter of the Earth. The images are the first ever made of the Sun with a facility where ESO is a partner. The results are an important expansion of the range of observations that can be used to probe the physics of our nearest star. The ALMA antennas had been carefully designed so they could image the Sun without being damaged by the intense heat of the focussed light.

Astronomers have harnessed ALMA's capabilities to image the millimetre-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, which forms the visible surface of the Sun. The solar campaign team, an international group of astronomers with members from Europe, North America and East Asia [1], produced the images as a demonstration of ALMA’s ability to study solar activity at longer wavelengths of light than are typically available to solar observatories on Earth.

Astronomers have studied the Sun and probed its dynamic surface and energetic atmosphere in many ways through the centuries. But, to achieve a fuller understanding, astronomers need to study it across the entire electromagnetic spectrum, including the millimetre and submillimetre portion that ALMA can observe.
Since the Sun is many billions of times brighter than the faint objects ALMA typically observes, the ALMA antennas were specially designed to allow them to image the Sun in exquisite detail using the technique of radio interferometry — and avoid damage from the intense heat of the focussed sunlight [2]. The result of this work is a series of images that demonstrate ALMA’s unique vision and ability to study our Sun.The data from the solar observing campaign are being released this week to the worldwide astronomical community for further study and analysis.

The team observed an enormous sunspot at wavelengths of 1.25 millimetres and 3 millimetres using two of ALMA's receiver bands. The images reveal differences in temperature between parts of the Sun's chromosphere [3]. Understanding the heating and dynamics of the chromosphere are key areas of research that will be addressed in the future using ALMA.

Sunspots are transient features that occur in regions where the Sun's magnetic field is extremely concentrated and powerful. They are lower in temperature than the surrounding regions, which is why they appear relatively dark.

The difference in appearance between the two images is due to the different wavelengths of emitted light being observed. Observations at shorter wavelengths are able to probe deeper into the Sun, meaning the 1.25 millimetre images show a layer of the chromosphere that is deeper, and therefore closer to the photosphere, than those made at a wavelength of 3 millimetres.

ALMA is the first facility where ESO is a partner that allows astronomers to study the nearest star, our own Sun. All other existing and past ESO facilities need to be protected from the intense solar radiation to avoid damage. The new ALMA capabilities will expand the ESO community to include solar astronomers.



Notes


[1] The ALMA Solar Campaign team includes: Shin'ichiro Asayama, East Asia ALMA Support Center, Tokyo, Japan; Miroslav Barta, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Tim Bastian, National Radio Astronomy Observatory, USA; Roman Brajsa, Hvar Observatory, Faculty of Geodesy, University of Zagreb, Croatia; Bin Chen, New Jersey Institute of Technology, USA; Bart De Pontieu, LMSAL, USA; Gregory Fleishman, New Jersey Institute of Technology, USA; Dale Gary, New Jersey Institute of Technology, USA; Antonio Hales, Joint ALMA Observatory, Chile; Akihiko Hirota, Joint ALMA Observatory, Chile; Hugh Hudson, School of Physics and Astronomy, University of Glasgow, UK; Richard Hills, Cavendish Laboratory, Cambridge, UK; Kazumasa Iwai, National Institute of Information and Communications Technology, Japan; Sujin Kim, Korea Astronomy and Space Science Institute, Daejeon, Republic of Korea; Neil Philips, Joint ALMA Observatory, Chile; Tsuyoshi Sawada, Joint ALMA Observatory, Chile; Masumi Shimojo (interferometry lead), NAOJ, Tokyo, Japan; Giorgio Siringo, Joint ALMA Observatory, Chile; Ivica Skokic, Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic; Sven Wedemeyer, Institute of Theoretical Astrophysics, University of Oslo, Norway; Stephen White (single dish lead), AFRL, USA; Pavel Yagoubov, ESO, Garching, Germany and Yihua Yan, NAO, Chinese Academy of Sciences, Beijing, China.

[2] Indeed, this lesson has been learned the hard way: the Swedish–ESO Submillimetre Telescope (SEST) had a fire in its secondary mirror assembly after the telescope was accidentally pointed at the Sun.

[3] A map of the whole disc of the Sun was also made with a single ALMA antenna, using a technique called fast-scanning, at a wavelength of 1.25 millimetres. The accuracy and speed of observing with a single ALMA antenna makes it possible to produce a map of the entire solar disc in just a few minutes. These maps show the distribution of temperatures in the chromosphere over the whole disc at low spatial resolution and therefore complement the detailed interferometric images of individual regions of interest.



More Information


The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.



Links



Contacts

Roman Brajsa
Hvar Observatory
University of Zagreb, Croatia
Tel: + 385 1 4639 318
Cell: + 385 99 2619 825
Email: romanb@geof.hr

Ivica Skokic
Astronomical Institute of the Czech Academy of Sciences
Ondrejov, Czech Republic
Tel: + 420 323 620 133
Cell: + 385 91 890 5815
Email: ivica.skokic@asu.cas.cz

Richard Hook

ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org


Source: ESO

Monday, January 16, 2017

Lyman-α Giant Halos Around Early Milky Way Type Galaxies

The figure shows some of the observations conducted with the INT and with the UKIRT in Hawaii of one of the (almost 1000) young Milky Way type galaxies in the very early Universe. The results allowed astronomers to measure where, and how many, Lyman-α photons were produced (indicated by the red contour lines), and then compare with those that have actually escaped (blue contour lines) these distant galaxies. The results reveal large haloes of Lyman-alpha photons that struggled to escape, while the vast majority of these photons never make it out at all. Credit: J. Matthee/D. Sobral. Large format: JPG


Astronomers from the Universities of Lancaster in the UK and Leiden in the Netherlands report the discovery of giant halos around early Milky Way type galaxies which are composed of Lyman-α photons that have struggled to escape them. 

In order to understand how our own Milky Way galaxy formed and evolved, astronomers can use observations of distant galaxies. As their light takes billions of years to reach us, telescopes can be used as time machines, as long as we have a clear time-travelling indicator to pin-point the distance. However, when we travel more than 11 billion years into the past, there is only one major photometric feature our telescopes can identify: Lyman α. 

Jorryt Matthee comments: "Newly born stars in very distant galaxies are hot enough to break apart hydrogen in surrounding clouds of gas, which then shine brightly in Lyman-α light, in theory the strongest of such features observable in a distant galaxy. Yet, in practice, Lyman-α photons struggle to escape from galaxies as gas and dust block and diverge their travel paths. As a consequence, these photons can escape some galaxies more easily than others, although the details are not well understood." 

Astronomers developed a unique experiment using the Isaac Newton Telescope (INT) to look at almost 1000 very distant galaxies. They surveyed the sky using the Wide Field Camera (WFC) and a custom-made filter in order to measure where, and how much, Lyman-α emission is produced, and where it comes out of galaxies. 

David Sobral says "We have used dozens of dedicated nights on the INT with our own narrow-band filter in order to understand how many Lyman-α photons escape and from which galaxies. We looked back in time 11 billion years, essentially the limit where we can still use multiple features to identify distant galaxies and study them in detail. Most importantly, we were able to predict accurately how many Lyman-α photons were effectively produced in each galaxy and where this happened. Then we compared them with the ones that actually reach the INT." 

The results show that only 1-2% of those photons escape from the centres of galaxies like the Milky Way. Even if we account for all the photons at a large distance from the centre, less than 10% escape. In other words, all galaxies forming stars in the distant Universe are surrounded by an impressively large halo of Lyman-α photons, which we can only detect if we conduct extremely deep observations.

On the other hand, galaxies that are bright in Lyman-α light typically are of much lower mass than the Milky Way and have a higher escape fraction. 

Astronomers expect that using the James Webb Space Telescope will be able to extend these studies to even higher look-back times, opening up a new window into the study of galaxy formation and evolution. Studying how escape fraction evolves with redshift can tell us about the kind of stars producing these photons, and the properties of interstellar and intergalactic gas.


More information:

Jorryt Matthee, David Sobral, Iván Oteo, Philip Best, Ian Smail, Huub Röttgering and Ana Paulino-Afonso, 2016, "The CALYMHA survey: Lyα escape fraction and its dependence on galaxy properties at z = 2.23", MNRAS, 458, 449 [ ADS ]. 

David Sobral, Jorryt Matthee, Philip Best, Andra Stroe, Huub Röttgering, Iván Oteo, Ian Smail, Leah Morabito, Ana Paulino-Afonso, 2017, "The CALYMHA survey: Lyα luminosity function and global escape fraction of Lyα photons at z=2.23", MNRAS, 466, 1242 [ Astro-ph ].

"Photons struggle to escape distant galaxies", RAS press release PR 17/1, 10 January 2017. 



Saturday, January 14, 2017

Farthest Stars in Milky Way Might Be Ripped from Another Galaxy

In this computer-generated image, a red oval marks the disk of our Milky Way galaxy and a red dot shows the location of the Sagittarius dwarf galaxy. The yellow circles represent stars that have been ripped from the Sagittarius dwarf and flung far across space. Five of the 11 farthest known stars in our galaxy were probably stolen this way. Credit: Marion Dierickx / CfA. High Resolution (jpg) - Low Resolution (jpg)

video
This movie simulates several passages of the Sagittarius dwarf galaxy past the galactic center (GC) of the Milky Way over the course of 8 billion years. The blue and red particles represent dark matter and stars, respectively. Credit:Marion Dierickx / CfA.  Animation (mov)

Cambridge, MA -The 11 farthest known stars in our galaxy are located about 300,000 light-years from Earth, well outside the Milky Way's spiral disk. New research by Harvard astronomers shows that half of those stars might have been ripped from another galaxy: the Sagittarius dwarf. Moreover, they are members of a lengthy stream of stars extending one million light-years across space, or 10 times the width of our galaxy.
"The star streams that have been mapped so far are like creeks compared to the giant river of stars we predict will be observed eventually," says lead author Marion Dierickx of the Harvard-Smithsonian Center for Astrophysics (CfA).

The Sagittarius dwarf is one of dozens of mini-galaxies that surround the Milky Way. Over the age of the universe it made several loops around our galaxy. On each passage, the Milky Way's gravitational tides tugged on the smaller galaxy, pulling it apart like taffy.

Dierickx and her PhD advisor, Harvard theorist Avi Loeb, used computer models to simulate the movements of the Sagittarius dwarf over the past 8 billion years. They varied its initial velocity and angle of approach to the Milky Way to determine what best matched current observations.

"The starting speed and approach angle have a big effect on the orbit, just like the speed and angle of a missile launch affects its trajectory," explains Loeb.

At the beginning of the simulation, the Sagittarius dwarf weighed about 10 billion times the mass of our Sun, or about one percent of the Milky Way's mass. Dierickx's calculations showed that over time, the hapless dwarf lost about a third of its stars and a full nine-tenths of its dark matter. This resulted in three distinct streams of stars that reach as far as one million light-years from the Milky Way's center. They stretch all the way out to the edge of the Milky Way halo and display one of the largest structures observable on the sky.

Moreover, five of the 11 most distant stars in our galaxy have positions and velocities that match what you would expect of stars stripped from the Sagittarius dwarf. The other six do not appear to be from Sagittarius, but might have been removed from a different dwarf galaxy.

Mapping projects like the Sloan Digital Sky Survey have charted one of the three streams predicted by these simulations, but not to the full extent that the models suggest. Future instruments like the Large Synoptic Survey Telescope, which will detect much fainter stars across the sky, should be able to identify the other streams.

"More interlopers from Sagittarius are out there just waiting to be found," says Dierickx.

These findings have been accepted for publication in The Astrophysical Journal and are available online.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint 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.

For more information, contact:

Christine Pulliam
Media Relations Manager
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu


Friday, January 13, 2017

A black hole of puzzling lightness

Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt


This image taken with the Advanced Camera for Surveys (ACS) onboard the NASA/ESA Hubble Space Telescope captures a galaxy in the Virgo constellation. This camera was installed in 2002, and its wide field of view is double that of its predecessor, capturing superb images with sharp image quality and enhanced sensitivity that can be seen here.

The beautiful spiral galaxy visible in the centre of the image is catchily known as RX J1140.1+0307, and it presents an interesting puzzle. At first glance, this galaxy appears to be a normal spiral galaxy, much like the Milky Way, but first appearances can be deceptive!

The Milky Way galaxy, like most large galaxies, has a supermassive black hole at its centre, but some galaxies are centred on lighter, intermediate-mass black holes. RX J1140.1+0307 is such a galaxy — in fact, it is centred on one of the lowest black hole masses known in any luminous galactic core. 

What puzzles scientists about this particular galaxy is that the calculations don’t add up. With such a relatively low mass for the central black hole, models for the emission from the object cannot explain the observed spectrum; unless there are other mechanisms at play in the interactions between the inner and outer parts of the accretion disc surrounding the black hole.



Thursday, January 12, 2017

Exploring a fast radio burst in three dimensions

Gemini composite image of the field around FRB 121102 (indicated). The dwarf host galaxy was imaged, and spectroscopy performed, using the Gemini Multi-Object Spectrograph (GMOS) on the Gemini North telescope on Maunakea in Hawai'i. Data was obtained on October 24-25 and November 2, 2016. Image Credit: Gemini Observatory/AURA/NSF/NRC. Full resolution TIFF/JPEG

video
Video animation (zoom-in) featuring Gemini Observatory optical imaging of FRB 121102 and surrounding field, ending with a radio flash based on NRAO radio data. Credit: Gemini Observatory/AURA/NRC/NSF/NRAO.  Download Video: Low Res MP4 (6.4mb) | High Res MP4 (58.1 MB) 


Gemini Probes Distant Host of Enigmatic Radio Bursts

Gemini Observatory provides critical rapid follow up observations of a Fast Radio Burst – one of modern astronomy's greatest enigmas. These observations provide the first details on a burst's distant extragalactic host. 

Fast Radio Bursts (FRBs), sudden rapid explosions of energy from space, have challenged astronomers since their discovery in 2007. Typically lasting only a few milliseconds, many questions remain, including what powers these bursts, their distance beyond our galaxy, and what their host galaxies might look like. 

"Now, thanks to deep Gemini observations, we know that at least one of these FRBs originated in a discrete source within a distant dwarf galaxy located some three billion light-years beyond our Milky Way Galaxy," said Shriharsh Tendulkar of McGill University in Montreal, Canada. 

Tendulkar and an international team of astronomers presented the results today at the 229th meeting of the American Astronomical Society in Grapevine, Texas. The characterization of the host galaxy was published in The Astrophysical Journal Letters, and accompanied the research team’s results on a campaign to precisely locate the FRB, published in the journal Nature

The story began with the detection of a burst denoted FRB 121102 which was discovered in November of 2012 at the Arecibo Observatory in Puerto Rico. However, unlike the other 17 known FRBs, this one repeated itself and allowed astronomers to watch for it using the National Science Foundation's Karl G. Jansky Very Large Array (VLA). The VLA radio telescope, composed of 27 antennas in New Mexico, has the ability to see the fine detail necessary to precisely determine the object's location in the sky. 

In 83 hours of observing time over six months in 2016, the VLA detected nine bursts from FRB 121102. "For a long time, we came up empty, then got a string of bursts that gave us exactly what we needed," said Casey Law, of the University of California at Berkeley. 

"The VLA data allowed us to narrow down the position very accurately," said Sarah Burke-Spolaor, of the National Radio Astronomy Observatory (NRAO) and West Virginia University. 

"Once we were able to accurately pinpoint the burst’s location in the two-dimensional sky we enlisted the 8-meter Gemini North telescope on Maunakea in Hawai‘i to characterize the corresponding host galaxy," said Paul Scholz formerly of McGill University and now with the National Research Council of Canada (NRC). "The Gemini observations did that, and for the first time with an FRB, left no doubt about its origin." 

"The host galaxy for this FRB appears to be a very humble and unassuming dwarf galaxy, which is only about 1% of the mass or our Milky Way Galaxy," said Tendulkar, who adds that Gemini not only imaged the galaxy, but obtained a spectrum which characterized the galaxy and provided an estimate of its redshift (velocity away from us due to the expansion of the Universe) and thus its distance. "This really gave us a three dimensional lock on the home of this FRB." 

"It is surprising that the host would be a dwarf galaxy," adds Tendulkar. "One would generally expect most FRBs to come from large galaxies which have the largest numbers of stars and neutron stars. Neutron stars – remnants of massive stars – are among the top candidates to explain FRBs. 

Tendulkar notes that this dwarf galaxy has fewer stars, but is forming them at a high rate, which may suggest that FRBs are linked to younger neutron stars. Two other classes of extreme events – long duration gamma-ray bursts and superluminous supernovae – frequently occur in dwarf galaxies, as well. "This discovery may hint at links between FRBs and those two kinds of events," suggests Tendulkar. 

"The collaboration of Gemini working with radio telescopes around the world, each looking at the Universe in such different ways, is what allowed us to make this breakthrough," said Shami Chatterjee, of Cornell University. "The simple fact that we have uncovered an extragalactic host for a fast radio burst is a huge advance in our understanding," he added. 

"This impressive result shows the power of several telescopes working in concert – first detecting the radio burst and then precisely locating and beginning to characterize the emitting source," said Phil Puxley, a program director at the National Science Foundation that funds the VLA, Very Long Baseline Array (VLBA), Gemini and Arecibo observatories. "It will be exciting to collect more data and better understand the nature of these radio bursts." 

"FRBs are an exciting new area in astrophysics and the CHIME telescope at DRAO is ideal for detecting large numbers of them across the whole sky," says Sean Dougherty, Director of the National Research Council of Canada (NRC) Dominion Radio Astrophysical Observatory (DRAO). In addition to funding a significant portion of Gemini, NRC hosts the Canadian Hydrogen Intensity Mapping Experiment (CHIME) which is an interferometric radio telescope under construction at DRAO in British Columbia. CHIME will survey half the sky each day in search of radio transients.


Contacts:

  • Peter Michaud
    Gemini Observatory
    Hilo, Hawai‘i
    Email:
    pmichaud@gemini.edu
    Cell: (808) 936-6643

Wednesday, January 11, 2017

Our Galaxy's Black Hole is Spewing Out Planet-size "Spitballs


"A single shredded star can form hundreds of these planet-mass objects. We wondered: Where do they end up? How close do they come to us? We developed a computer code to answer those questions," says lead author Eden Girma, an undergraduate student at Harvard University and a member of the Banneker/Aztlan Institute.

Girma is presenting her findings at a Wednesday poster session and Friday press conference at a meeting of the American Astronomical Society.

Girma's calculations show that the closest of these planet-mass objects might be within a few hundred light-years of Earth. It would have a weight somewhere between Neptune and several Jupiters. It would also glow from the heat of its formation, although not brightly enough to have been detected by previous surveys. Future instruments like the Large Synoptic Survey Telescope and James Webb Space Telescope might spot these far-flung oddities.

She also finds that the vast majority of the planet-mass objects - 95 percent - will leave the galaxy entirely due to their speeds of about 20 million miles per hour (10,000 km/s). Since most other galaxies also have giant black holes at their cores, it’s likely that the same process is at work in them.
"Other galaxies like Andromeda are shooting these 'spitballs' at us all the time," says co-author James Guillochon of the Harvard-Smithsonian Center for Astrophysics (CfA).

Although they might be planet-size, these objects would be very different from a typical planet. They are literally made of star-stuff, and since different ones would develop from different pieces of the former star, their compositions could vary.

They also form much more rapidly than a normal planet. It takes only a day for the black hole to shred the star (in a process known as tidal disruption), and only about a year for the resulting fragments to pull themselves back together. This is in contrast to the millions of years required to create a planet like Jupiter from scratch.

Once launched, it would take about a million years for one of these objects to reach Earth’s neighborhood. The challenge will be to tell it apart from free-floating planets that are created during the more mundane process of star and planet formation.

"Only about one out of a thousand free-floating planets will be one of these second-generation oddballs," adds Girma.

Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for Astrophysics (CfA) is a joint 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.


For more information, contact:

Christine Pulliam
Media Relations Manager
Harvard-Smithsonian Center for Astrophysics
617-495-7463
cpulliam@cfa.harvard.edu



Tuesday, January 10, 2017

VLT to Search for Planets in Alpha Centauri

The Very Large Telescope and the star system Alpha Centauri 

The Alpha Centauri Star System

Videos

ESOcast 91 Light: VLT to search for planets around Alpha Centauri 4K UHD
ESOcast 91 Light: VLT to search for planets around Alpha Centauri 4K UHD



ESO Signs Agreement with Breakthrough Initiatives

ESO has signed an agreement with the Breakthrough Initiatives to adapt the Very Large Telescope instrumentation in Chile to conduct a search for planets in the nearby star system Alpha Centauri. Such planets could be the targets for an eventual launch of miniature space probes by the Breakthrough Starshot initiative.

ESO, represented by the Director General, Tim de Zeeuw, has signed an agreement with the Breakthrough Initiatives, represented by Pete Worden, Chairman of the Breakthrough Prize Foundation and Executive Director of the Breakthrough Initiatives. The agreement provides funds for the VISIR (VLT Imager and Spectrometer for mid-Infrared) instrument, mounted at ESO’s Very Large Telescope (VLT) to be modified in order to greatly enhance its ability to search for potentially habitable planets around Alpha Centauri, the closest stellar system to the Earth. The agreement also provides for telescope time to allow a careful search programme to be conducted in 2019.

The discovery in 2016 of a planet, Proxima b, around Proxima Centauri, the third and faintest star of the Alpha Centauri system, adds even further impetus to this search.

Knowing where the nearest exoplanets are is of paramount interest for Breakthrough Starshot, the research and engineering programme launched in April 2016, which aims to demonstrate proof of concept for ultra-fast light-driven “nanocraft”, laying the foundation for the first launch to Alpha Centauri within a generation.

Detecting a habitable planet is an enormous challenge due to the brightness of the planetary system’s host star, which tends to overwhelm the relatively dim planets. One way to make this easier is to observe in the mid-infrared wavelength range, where the thermal glow from an orbiting planet greatly reduces the brightness gap between it and its host star. But even in the mid-infrared, the star remains millions of times brighter than the planets to be detected, which calls for a dedicated technique to reduce the blinding stellar light.

The existing mid-infrared instrument VISIR on the VLT will provide such performance if it were enhanced to greatly improve the image quality using adaptive optics, and adapted to employ a technique called coronagraphy to reduce the stellar light and thereby reveal the possible signal of potential terrestrial planets. Breakthrough Initiatives will pay for a large fraction of the necessary technologies and development costs for such an experiment, and ESO will provide the required observing capabilities and time.

The new hardware includes an instrument module contracted to Kampf Telescope Optics (KTO), Munich, which will host the wavefront sensor, and a novel detector calibration device. In addition, there are plans for a new coronagraph to be developed jointly by University of Liège (Belgium) and Uppsala University (Sweden).

Detecting and studying potentially habitable planets orbiting other stars will be one of the main scientific goals of the upcoming European Extremely Large Telescope (E-ELT). Although the increased size of the E-ELT will be essential to obtaining an image of a planet at larger distances in the Milky Way, the light collecting power of the VLT is just sufficient to image a planet around the nearest star, Alpha Centauri.

The developments for VISIR will also be beneficial for the future METIS instrument, to be mounted on the E-ELT, as the knowledge gained and proof of concept will be directly transferable. The huge size of the E-ELT should allow METIS to detect and study exoplanets the size of Mars orbiting Alpha Centauri, if they exist, as well as other potentially habitable planets around other nearby stars.



More Information

The Breakthrough Initiatives are a program of scientific and technological exploration founded in 2015 by Internet investor and science philanthropist Yuri Milner to explore the Universe, seek scientific evidence of life beyond Earth, and encourage public debate from a planetary perspective.

Breakthrough Starshot is a $100 million research and engineering program aiming to demonstrate proof of concept for a new technology, enabling ultra-light unmanned space flight at 20% of the speed of light, and to lay the foundations for a flyby mission to Alpha Centauri within a generation.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.



Links



Contacts

Markus Kasper
ESO
Garching bei München, Germany
Tel: +49 89 3200 6359

Breakthrough Initiatives

Janet Wootten
Rubenstein Communications, Inc.
Tel: +1 212 843 8024

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591

Source: ESO

The Case of the 'Missing Link' Neutron Star

This artist's concept shows a pulsar, which is like a lighthouse, as its light appears in regular pulses as it rotates. 
Image credit: NASA/JPL-Caltech.  › Full image and caption


Like anthropologists piecing together the human family tree, astronomers have found that a misfit "skeleton" of a star may link two different kinds of stellar remains. The mysterious object, called PSR J1119-6127, has been caught behaving like two distinct objects -- a radio pulsar and a magnetar -- and could be important to understanding their evolution.

A radio pulsar is type of a neutron star -- the extremely dense remnant of an exploded star -- that emits radio waves in predictable pulses due to its fast rotation. Magnetars, by contrast, are rabble rousers: They have violent, high-energy outbursts of X-ray and gamma ray light, and their magnetic fields are the strongest known in the universe.

"This neutron star wears two different hats," said Walid Majid, astrophysicist at NASA's Jet Propulsion Laboratory, Pasadena, California. "Sometimes it's a pulsar. Sometimes it's a magnetar. 

This object may tell us something about the underlying mechanism of pulsars in general."

Since the 1970s, scientists have treated pulsars and magnetars as two distinct populations of objects. 

But in the last decade, evidence has emerged that these could be stages in the evolution of a single object. Majid's new study, combined with other observations of the object, suggests that J1119 could be in a never-before-seen transition state between radio pulsar and magnetar. The study was published in the Jan. 1 issue of Astrophysical Journal Letters, and was presented this week at the American Astronomical Society meeting in Grapevine, Texas.

"This is the final missing link in the chain that connects pulsars and magnetars," said Victoria Kaspi, astrophysicist at McGill University in Montreal, Canada. "It seems like there's a smooth transition between these two kinds of neutron star behaviors."

When this mysterious object was discovered in 2000, it appeared to be a radio pulsar. It was mostly quiet and predictable until July 2016, when NASA's Fermi and Swift space observatories observed two X-ray bursts and 10 additional bursts of light at lower energies coming from the object, as reported in a study in the Astrophysical Journal Letters led by Ersin Gogus. An additional 2016 study in the same journal, led by Robert Archibald, also looked at the two X-ray bursts, incorporating observations from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) telescope. This study also suggested that the pulsar was behaving rebelliously -- like a magnetar.

When the outbursts happened, Kaspi excitedly emailed astrophysicist Tom Prince at JPL/Caltech in Pasadena, telling him this would be a good object to study from the southern hemisphere. Prince, Majid and colleagues used the NASA Deep Space Network 70-meter radio telescope in Canberra, Australia -- the largest dish in the southern hemisphere -- to see what was going on.

"We think these X-ray bursts happened because the object's enormous magnetic field got twisted as the object was spinning," Majid said.

The stress of a twisting magnetic field is so great that it causes the outer crust of the neutron star to break -- analogous to tectonic plates on Earth causing earthquakes. This causes an abrupt change in rotation, called a "glitch," which has been measured by NuSTAR.

Neutron stars are so dense that one teaspoon weighs as much as a mountain. The star's crust, roughly 0.6 miles (1 kilometer) thick, with higher pressure and density at greater depths, is a neutron-rich lattice. This particular neutron star is thought to have one of the strongest magnetic fields among the population of known pulsars: a few trillion times stronger than the magnetic field of the sun.

Two weeks after the X-ray outburst, Majid and colleagues tracked the object's emissions at radio frequencies, which are much lower in energy than X-rays. The radio emissions had sharp increases and decreases in intensity, allowing scientists to quantify how the emission evolved. Researchers used an instrument, which they informally call a "pulsar machine," that was recently installed at the same DSN dish in Australia.

"Within 10 days, something completely changed in the pulsar," Majid said. "It had started behaving like a normal radio pulsar again."
The question remains: Which came first, the pulsar or the magnetar? Some scientists argue that objects like J1119 begin as magnetars and gradually stop outbursting X-rays and gamma rays over time. But others propose the opposite theory: that the radio pulsar comes first and, over time, its magnetic field emerges from the supernova's rubble, and then the magnetar-like outbursts begin. But, just as babies grow to be adults and not vice versa, there is likely a single path for these objects to take.

To help solve this mystery, much as anthropologists study the remains of human ancestors at different stages of evolutionary history, astronomers want to find more "missing link" objects like J1119. This particular object was likely formed following a supernova 1,600 years ago. Monitoring similar objects may shed light on whether this phenomenon is specific to J1119, or whether this behavior is common in this class of objects.

Astronomers continue to monitor J1119 as well. Majid and colleagues observed in December a marked brightening of emissions at radio wavelengths, in a pattern consistent with other magnetars.

"Our recent observations show that this object contains a bit of the 'astrophysical DNA' of two different families of neutron stars," Prince said. "We are looking forward to finding other examples of this type of transitional object."

JPL, a division of Caltech, manages the Deep Space Network for NASA.


News Media Contact

Elizabeth Landau
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-6425

elizabeth.landau@jpl.nasa.gov

Source: JPL-Caltech