Thursday, November 30, 2017

Giant Black Hole Pair Photobombs Andromeda Galaxy

 M31/LGGS J004527.30+413254.3
Credit X-ray: NASA/CXC/Univ. of Washington/T.Dorn-Wallenstein et al.; 
Optical: NASA/ESA/J. Dalcanton, et al. & R. Gendler




An intriguing source has been discovered in the nearby Andromeda galaxy using data from NASA's Chandra X-ray Observatory and ground-based optical telescopes. Previously thought to be part of the Milky Way's neighbor galaxy, the new research shows this source is actually a very distant object 2.6 billion light years away that is acting as a cosmic bomb, as reported in our press release.

This graphic shows the Chandra data (blue in inset) of the source known as LGGS J004527.30+413254.3 (J0045+41 for short) in the context of optical images of Andromeda from the Hubble Space Telescope. In the inset image, north is up and in the large image north is to the lower right. Andromeda, also known as M31, is a spiral galaxy located about 2.5 million light years from Earth.

Even more intriguing than the large distance of J0045+41 is that it likely contains a pair of giant black holes in close orbit around each other. The estimated total mass for these two supermassive black holes is about two hundred million times that of our Sun.

J0045+41 was previously classified as a different type of object — a pair of orbiting stars — when it was thought to occupy Andromeda. A team of researchers combined the Chandra X-ray data with spectra from the Gemini North telescope in Hawaii, providing evidence that J0045+41 contained at least one supermassive black hole. Using data from the Palomar Transient Factory telescopes in California, the team found repeating variations in the light from J0045+41, a pointer to the presence of two orbiting giant black holes.

The researchers estimate that the two putative black holes orbit each other with a separation of only a few hundred times the distance between the Earth and the Sun. This corresponds to less than one hundredth of a light year. By comparison, the nearest star to our Sun is about four light years away.

Such a system could be formed as a consequence of the merger, billions of years earlier, of two galaxies that each contained a supermassive black hole. At their current close separation, the two black holes are inevitably being drawn closer together as they emit gravitational waves.

A paper describing this result was accepted for publication in The Astrophysical Journal and a preprint 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 J0045+41:

 Scale: Full image is 1 degree across. Inset is 15 arcsec across (172 light years)
Category: Quasars & Active Galaxies, Black Holes
Observation Date: October 19, 2015
Observation Time: 13 hours 43 minutes
Obs. ID: 17010
Instrument: ACIS
References: Dorn-Wallenstein, et al., 2017, ApJ, 850, 86; arXiv:1704.08694
Color Code: X-ray (Blue), Optical (red, green, blue)
Distance Estimate: About 2.6 billion light years (z=0.215)



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MUSE Probes Uncharted Depths of Hubble Ultra Deep Field

The Hubble Ultra Deep Field seen with MUSE

PR Image eso1738b
The Hubble Ultra Deep Field 2012

PR Image eso1738c
Glowing haloes around distant galaxies


Videos

ESOcast 140 Light: MUSE Dives into the Hubble Ultra Deep Field
ESOcast 140 Light: MUSE Dives into the Hubble Ultra Deep Field

Zooming into the MUSE view of the Hubble Ultra Deep Field
Zooming into the MUSE view of the Hubble Ultra Deep Field

Panning across the MUSE view of the Hubble Ultra Deep Field
Panning across the MUSE view of the Hubble Ultra Deep Field

Flying through the MUSE view of the Hubble Ultra Deep Field
Flying through the MUSE view of the Hubble Ultra Deep Field

MUSE charts distances in the Hubble Ultra Dee Field
MUSE charts distances in the Hubble Ultra Dee Field

MUSE reveals glowing haloes around distant galaxies
MUSE reveals glowing haloes around distant galaxies


Deepest ever spectroscopic survey completed

Astronomers using the MUSE instrument on ESO’s Very Large Telescope in Chile have conducted the deepest spectroscopic survey ever. They focused on the Hubble Ultra Deep Field, measuring distances and properties of 1600 very faint galaxies including 72 galaxies that have never been detected before, even by Hubble itself. This groundbreaking dataset has already resulted in 10 science papers that are being published in a special issue of Astronomy & Astrophysics. This wealth of new information is giving astronomers insight into star formation in the early Universe, and allows them to study the motions and other properties of early galaxies — made possible by MUSE’s unique spectroscopic capabilities.

The MUSE HUDF Survey team, led by Roland Bacon of the Centre de recherche astrophysique de Lyon (CNRS/Université Claude Bernard Lyon 1/ENS de Lyon), France, used MUSE (Multi Unit Spectroscopic Explorer) to observe the Hubble Ultra Deep Field (heic0406), a much-studied patch of the southern constellation of Fornax (The Furnace). This resulted in the deepest spectroscopic observations ever made; precise spectroscopic information was measured for 1600 galaxies, ten times as many galaxies as has been painstakingly obtained in this field over the last decade by ground-based telescopes.

The original HUDF images were pioneering deep-field observations with the NASA/ESA Hubble Space Telescope published in 2004. They probed more deeply than ever before and revealed a menagerie of galaxies dating back to less than a billion years after the Big Bang. The area was subsequently observed many times by Hubble and other telescopes, resulting in the deepest view of the Universe to date [1]. Now, despite the depth of the Hubble observations, MUSE has — among many other results — revealed 72 galaxies never seen before in this very tiny area of the sky.

Roland Bacon takes up the story: “MUSE can do something that Hubble can’t — it splits up the light from every point in the image into its component colours to create a spectrum. This allows us to measure the distance, colours and other properties of all the galaxies we can see — including some that are invisible to Hubble itself.”

The MUSE data provides a new view of dim, very distant galaxies, seen near the beginning of the Universe about 13 billion years ago. It has detected galaxies 100 times fainter than in previous surveys, adding to an already richly observed field and deepening our understanding of galaxies across the ages.

The survey unearthed 72 candidate galaxies known as Lyman-alpha emitters that shine only in Lyman-alpha light [2]. Current understanding of star formation cannot fully explain these galaxies, which just seem to shine brightly in this one colour. Because MUSE disperses the light into its component colours these objects become apparent, but they remain invisible in deep direct images such as those from Hubble.

“MUSE has the unique ability to extract information about some of the earliest galaxies in the Universe — even in a part of the sky that is already very well studied,” explains Jarle Brinchmann, lead author of one of the papers describing results from this survey, from the University of Leiden in the Netherlands and the Institute of Astrophysics and Space Sciences at CAUP in Porto, Portugal. “We learn things about these galaxies that is only possible with spectroscopy, such as chemical content and internal motions — not galaxy by galaxy but all at once for all the galaxies!”

Another major finding of this study was the systematic detection of luminous hydrogen halos around galaxies in the early Universe, giving astronomers a new and promising way to study how material flows in and out of early galaxies.

Many other potential applications of this dataset are explored in the series of papers, and they include studying the role of faint galaxies during cosmic reionisation (starting just 380 000 years after the Big Bang), galaxy merger rates when the Universe was young, galactic winds, star formation as well as mapping the motions of stars in the early Universe.

“Remarkably, these data were all taken without the use of MUSE’s recent Adaptive Optics Facility upgrade. The activation of the AOF after a decade of intensive work by ESO’s astronomers and engineers promises yet more revolutionary data in the future,” concludes Roland Bacon [3].


Notes
[1] The Hubble Ultra Deep Field is one of the most extensively studied areas of space. To date, 13 instruments on eight telescopes, including the ESO-partnered ALMA (eso1633), have observed the field from X-ray to radio wavelengths.

[2] The negatively-charged electrons that orbit the positively-charged nucleus in an atom have quantised energy levels. That is, they can only exist in specific energy states, and they can only transition between them by gaining or losing precise amounts of energy. Lyman-alpha radiation is produced when electrons in hydrogen atoms drop from the second-lowest to the lowest energy level. The precise amount of energy lost is released as light with a particular wavelength in the ultraviolet part of the spectrum, which astronomers can detect with space telescopes or on Earth in the case of redshifted objects. For this data, at redshift of z ~ 3–6.6, the Lyman-alpha light is seen as visible or near-infrared light.

[3] The Adaptive Optics Facility with MUSE has already revealed previously unseen rings around the planetary nebula IC 4406 (eso1724).


More Information

This research was presented in a series of 10 papers to appear in the journal Astronomy & Astrophysics.

The teams are composed of Roland Bacon (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, Université de Lyon, Lyon, France), Hanae Inami (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, Université de Lyon, Lyon, France), Jarle Brinchmann (Leiden Observatory, Leiden, the Netherlands; Instituto de Astrofísica e Ciências do Espaço, Porto, Portugal), Michael Maseda (Leiden Observatory, Leiden, the Netherlands), Adrien Guerou (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES, Université de Toulouse, France; ESO, Garching, Germany), A. B. Drake (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon, Université de Lyon, Lyon, France), H. Finley (IRAP, Université de Toulouse, Toulouse, France), F. Leclercq (University of Lyon, Lyon, France), E. Ventou (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES Université de Toulouse, Toulouse, France), T. Hashimoto (University of Lyon, Lyon, France), Simon Conseil (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), David Mary (Laboratoire Lagrange, CNRS, Observatoire de la Côte d’Azur, Université de Nice, Nice, France), Martin Shepherd (University of Lyon, Lyon, France), Mohammad Akhlaghi (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Peter M. Weilbacher (Leibniz-Institut für Astrophysik Postdam, Postdam, Germany), Laure Piqueras (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Lutz Wisotzki (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), David Lagattuta (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Benoit Epinat (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES, Université de Toulouse, Toulouse, France; and LAM, CNRS / Aix Marseille Université, Marseille, France), Sebastiano Cantalupo (ETH Zurich, Zurich, Switzerland), Jean Baptiste Courbot (University of Lyon, Lyon, France; ICube, Université de Strasbourg, Strasbourg, France), Thierry Contini (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES Université de Toulouse, Toulouse, France), Johan Richard (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Rychard Bouwens (Leiden Observatory, Leiden, the Netherlands), Nicolas Bouché (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES Université de Toulouse, Toulouse, France), Wolfram Kollatschny (AIG, Universität Göttingen, Göttingen, Germany), Joop Schaye (Leiden Observatory, Leiden, the Netherlands), Raffaella Anna Marino (ETH Zurich, Zurich, Switzerland), Roser Pello (IRAP, CNRS, Université Toulouse III – Paul Sabatier, CNES Université de Toulouse, Toulouse, France), Bruno Guiderdoni (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Marcella Carollo (ETH Zurich, Zurich, Switzerland), S. Hamer (University of Lyon, Lyon, France), B. Clément (University of Lyon, Lyon, France), G. Desprez (University of Lyon, Lyon, France), L. Michel-Dansac (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), M. Paalvast (Leiden Observatory, Leiden, the Netherlands), L. Tresse (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), L. A. Boogaard (Leiden Observatory, Leiden, the Netherlands), J. Chevallard (Scientific Support Office, ESA/ESTEC, Noordwijk, the Netherlands) S. Charlot (Sorbonne University, Paris, France), J. Verhamme (University of Lyon, Lyon, France), Marijn Franx (Leiden Observatory, Leiden, the Netherlands), Kasper B. Schmidt (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), Anna Feltre (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Davor Krajnović (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany), Eric Emsellem (ESO, Garching, Germany; University of Lyon, Lyon, France), Mark den Brok (ETH Zurich, Zurich, Switzerland), Santiago Erroz-Ferrer (ETH Zurich, Zurich, Switzerland), Peter Mitchell (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Thibault Garel (University of Lyon, Lyon, France), Jeremy Blaizot (CRAL - CNRS, Université Claude Bernard Lyon 1, ENS de Lyon Université de Lyon, Lyon, France), Edmund Christian Herenz (Department of Astronomy, Stockholm University, Stockholm, Sweden), D. Lam (Leiden University, Leiden, the Netherlands), M. Steinmetz (Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany) and J. Lewis (University of Lyon, Lyon, France).

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 and by Australia as a strategic partner. 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 Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.


Links


Contacts

Roland Bacon
Lyon Centre for Astrophysics Research (CRAL)
France
Cell: +33 6 08 9 14 27
Email: roland.bacon@univ-lyon1.fr

Jarle Brinchmann
University of Leiden
Netherlands
Cell: +31 6 50 92 51 89
Email: jarle@strw.leidenuniv.nl

Davor Krajnovic
Leibniz Institute for Astrophysics Potsdam
Germany
Cell: +49 160 24 34 574
Email: dkrajnovic@aip.de

Thierry Contini
Institut de Recherche en Astrophysique et Planétologie
France
Cell: +33 6 62 64 12 68
Email: thierry.contini@irap.omp.eu

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

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Wednesday, November 29, 2017

Hubble and Gaia team up to measure 3D stellar motion with record-breaking precision

Hubble’s view of the Sculptor Dwarf Galaxy (pointing 1)

PR Image heic1719b
Hubble’s view of the Sculptor Dwarf Galaxy (pointing 2)

PR Image heic1719c
Sculptor Dwarf Galaxy (ground-based view)

PR Image heic1719d
Wide-field image of the sky around the Sculptor Dwarf Galaxy

PR Image heic1719e
Hubble observing the Sculptor Dwarf Galaxy

PR Image heic1719f
ESA’s Gaia satellite



Videos
 
Zoom on a a part of the Sculptor Dwarf Galaxy
Zoom on a a part of the Sculptor Dwarf Galaxy


A team of astronomers used data from both the NASA/ESA Hubble Space Telescope and ESA’s Gaia satellite to directly measure the 3D motions of individual stars in a nearby galaxy. The achieved accuracy is better than anything previously measured for a galaxy beyond the Milky Way. The motions provide a field test of the currently-accepted cosmological model and also measure the trajectory of the galaxy through space. The results are published in Nature Astronomy.

Astronomers from the Kapteyn Astronomical Institute and Leiden Observatory, both in the Netherlands, used data from the NASA/ESA Hubble Space Telescope and ESA’s Gaia space observatory to measure the motions of stars in the Sculptor Dwarf Galaxy. The Sculptor Dwarf is a satellite galaxy orbiting the Milky Way, 300 000 light-years away from Earth.

Only by combining the datasets from these two successful ESA missions — produced more than 12 years apart — could the scientists directly measure the exact 3D motions of stars within the Sculptor Dwarf Galaxy [1]. The is the first time this has been achieved with such accuracy for a galaxy other than the Milky Way [2].

Davide Massari, lead author of the study, describes the precision of the research: “With the precision achieved we can measure the yearly motion of a star on the sky which corresponds to less than the size of a pinhead on the Moon as seen from Earth.” This kind of precision was only possible due to the extraordinary resolution and accuracy of both instruments. Also the study would not have been possible without the large interval of time between the two datasets which makes it easier to determine the movement of the stars.

The Sculptor Dwarf Galaxy is a dwarf spheroidal galaxy, which are among the most dark matter dominated objects in the Universe. This makes them ideal targets for investigating the properties of dark matter. In particular, understanding how dark matter is distributed in these dwarf galaxies allows astronomers to test the validity of the currently-accepted cosmological model. However, dark matter cannot be studied directly.

“One of the best ways to infer the presence of dark matter is to examine how objects move within it,” explains Amina Helmi, co-author of the paper. “In the case of dwarf spheroidals, these objects are stars.”

The information gathered about the 3D motion of stars in the Sculptor Dwarf Galaxy can be translated directly into knowledge of how its total mass — including dark matter — is distributed.

The new results show that stars in the Sculptor Dwarf Galaxy move preferentially on elongated radial orbits. This indicates that the density of dark matter increases towards the centre instead of flattening out. These findings are in agreement with the established cosmological model and our current understanding of dark matter, taking into account the complexity of Sculptor’s stellar populations.

As a side effect of the study, the team also presented a more accurate trajectory of the Sculptor Dwarf Galaxy as a whole as it orbits the Milky Way. Their results show that it is moving around the Milky Way in a high-inclination elongated orbit that takes it much further away than previously thought.

Currently, it is nearly at its closest point to the Milky Way, but its orbit can take it as far as 725 000 light-years away.

“With these pioneering measurements, we enter an era where measuring 3D motions of stars in other galaxies will become routine and will be possible for larger star samples. This will mostly be thanks to ESA’s Gaia mission,” concludes Massari.


Notes

[1] The team measured the proper motions of roughly a hundred stars in the Sculptor Dwarf Galaxy. 

For a smaller subset of ten stars, chosen among those with the smallest errors, the astronomers could also retrieve from the literature an estimate of the radial velocity, which quantifies the stellar motion along the line of sight. Using the proper motion and radial velocity measurements, they were able to reconstruct how these stars move in three dimensions.

 [2] The data used contain images taken with Hubble’s Advanced Camera for Surveys in 2002. Newer positions of individual stars were taken from the Gaia, which was observed between 2014 and 2015.


More Informatiom
The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Gaia is an ESA mission to survey one billion stars in our Galaxy and local galactic neighbourhood in order to build the most precise 3D map of the Milky Way and answer questions about its structure, origin and evolution. A large pan-European team of expert scientists and software developers, the Data Processing and Analysis Consortium (DPAC), located in and funded by many ESA member states, is responsible for the processing and validation of Gaia's data, with the final objective of producing the Gaia Catalogue.

The international team of astronomers in this study consists of D. Massari (University of Groningen, The Netherlands), M. A. Breddels (University of Groningen, The Netherlands), A. Helmi (University of Groningen, The Netherlands), L. Posti (University of Groningen, The Netherlands), A. G. A. Brown (Leiden University, The Netherlands) and E. Tolstoy (University of Groningen, The Netherlands).

 Image credit: ESA/Hubble & NASA, ESA/ATG medialab, Digitized Sky Survey 2


Links


Contacts

 Davide Massari
Kapteyn Astronomical Institute
Groningen, The Netherlands
Tel: +31 50363 4094
Email: massari@astro.rug.nl

Amina Helmi
Kapteyn Astronomical Institute
Groningen, The Netherlands
Tel: +31 50363 4045
Email: ahelmi@astro.rug.nl

Mathias Jäger
ESA/Hubble, Public Information Officer
Garching bei München, Germany
Cell: +49 176 62397500
Email: mjaeger@partner.eso.org


Source: ESA/Hubble/News

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Tuesday, November 28, 2017

Newly Discovered Twin Planets Could Solve Puffy Planet Mystery

Upper left: Schematic of the K2-132 system on the main sequence. Lower left: Schematic of the K2-132 system now. The host star has become redder and larger, irradiating the planet more and thus causing it to expand. Sizes not to scale.  Main panel: Gas giant planet K2-132b expands as its host star evolves into a red giant. The energy from the host star is transferred from the planet's surface to its deep interior, causing turbulence and deep mixing in the planetary atmosphere. The planet orbits its star every nine days and is located about 2000 light years away from us in the constellation Virgo.  Credit: Karen Teramura, UH IFA

Maunakea, Hawaii - Since astronomers first measured the size of an extrasolar planet seventeen years ago, they have struggled to answer the question: how did the largest planets get to be so large? 

Thanks to the recent discovery of twin planets by a University of Hawaii Institute for Astronomy team led by graduate student Samuel Grunblatt, scientists are getting closer to an answer.

Gas giant planets are primarily made out of hydrogen and helium, and are at least four times the diameter of Earth. Gas giant planets that orbit scorchingly close to their host stars are known as "hot Jupiters." These planets have masses similar to Jupiter and Saturn, but tend to be much larger - some are puffed up to sizes even larger than the smallest stars.

The unusually large sizes of these planets are likely related to heat flowing in and out of their atmospheres, and several theories have been developed to explain this process. "However, since we don't have millions of years to see how a particular planetary system evolves, planet inflation theories have been difficult to prove or disprove," said Grunblatt.

To solve this issue, Grunblatt searched through data collected by NASA's K2 Mission to hunt for hot Jupiters orbiting red giant stars. These stars, which are in the late stages of their lives, become themselves significantly larger over their companion planet's lifetime. Following a theory put forth by Eric Lopez of NASA's Goddard Space Flight Center, hot Jupiters orbiting red giant stars should be highly inflated if direct energy input from the host star is the dominant process inflating planets.

The search has now revealed two planets, each orbiting their host star with a period of approximately nine days. Using stellar oscillations to precisely calculate the radii of both the stars and planets, the team found that the planets are 30 percent larger than Jupiter. 

Observations using the W. M. Keck Observatory on Maunakea, Hawaii also showed that, despite their large sizes, the planets were only half as massive as Jupiter. Remarkably, the two planets are near twins in terms of their orbital periods, radii, and masses.

Using models to track the evolution of the planets and their stars over time, the team calculated the planets' efficiency at absorbing heat from the star and transferring it to their deep interiors, causing the whole planet to expand in size and decrease in density. Their findings show that these planets likely needed the increased radiation from the red giant star to inflate, but the amount of radiation absorbed was also lower than expected.

It is risky to attempt to reach strong conclusions with only two examples. But these results begin to rule out some explanations of planet inflation, and are consistent with a scenario where planets are directly inflated by the heat from their host stars. The mounting scientific evidence seems to suggest that stellar radiation alone can directly alter the size and density of a planet.

Our own Sun will eventually become a red giant star, so it's important to quantify the effect its evolution will have on the rest of the Solar System. "Studying how stellar evolution affects planets is a new frontier, both in other solar systems as well as our own," said Grunblatt. "With a better idea of how planets respond to these changes, we can start to determine how the Sun's evolution will affect the atmosphere, oceans, and life here on Earth."

The search for gas giant planets around red giant stars continues since additional systems could conclusively distinguish between planet inflation scenarios. Grunblatt and his team have been awarded time with the NASA Spitzer Space Telescope to measure the sizes of these twin planets more accurately. In addition, the search for planets around red giants with the NASA K2 Mission will continue for at least another year, and NASA's Transiting Exoplanet Survey Satellite (TESS), launching in 2018, will observe hundreds of thousands of red giants across the entire sky.

"Seeing double with K2: Testing re-inflation with two remarkably similar planets orbiting red giant branch stars" has been published in November 27th edition of The Astronomical Journal as and is available online at http://iopscience.iop.org/article/10.3847/1538-3881/aa932d.


Contacts

Sam Grunblatt
skg3@hawaii.edu
Cell: 845-430-4603

Dr. Daniel Huber
huberd@hawaii.edu
Office: 808-956-8573

Dr. Roy Gal
Media Contact
Office: 808-956-6235
Cell: 301-728-8637
rgal@ifa.hawaii.edu


About W. M. Keck Observatory


The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two, 10-meter optical/infrared telescopes on the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems. 

Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.


Article Summary


A University of Hawaii Institute for Astronomy-led team discovers unusually large twin exoplanets. Desipite their large sizes, observations using the W. M. Keck Observatory on Maunakea, Hawaii show that the planets are only half as massive as Jupiter. The discovery could help astronomers understand how the largest planets became so large.




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Friday, November 24, 2017

Cosmic snake pregnant with stars

MACSJ1206.2-0847
Credit: ESA/Hubble, NASA


This NASA/ESA Hubble Space Telescope image reveals the Cosmic Snake, a distant galaxy peppered with clumpy regions of intense star formation that appear warped by the effect of gravitational lensing. This giant arc-like galaxy is actually behind the huge galaxy cluster MACSJ1206.2-0847, but thanks to the cluster’s gravity, we can see it from Earth.

Light from the distant, high-redshift galaxy arrives at Earth, having been distorted by the gigantic gravitational influence of the intervening cluster. Fascinatingly, instead of making it more difficult to perceive cosmological objects, such strong lensing effects improve the resolution and depth of an image by magnifying the background object. Sometimes gravitational lensing can even produce multiple images of the object as light is bent in different directions around the foreground cluster.

Using Hubble, astronomers recently looked at several such images of the Cosmic Snake, each with a different level of magnification. Using this technique, the galaxy and its features could be studied on different scales. The highest-resolution images revealed that giant clumps in high-redshift galaxies are made up of a complex substructure of smaller clumps, which contributes to our understanding of star formation in distant galaxies.


Links 




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Thursday, November 23, 2017

MUSE spies accreting giant structure around a quasar

Credit: ESO/Arrigoni Battaia et al.


This Picture of the Week shows a huge cloud of gas around the distant quasar SDSS J102009.99+104002.7, taken by the Multi Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT) at the Paranal Observatory. Quasars are the luminous centres of active galaxies, which are kept active by material falling onto the central supermassive black hole. This quasar and its surrounding cloud are at a redshift larger than 3, meaning that they are seen as they were only about 2 billion years after the Big Bang.

The cloud of gas (or nebula) surrounding the quasar is known to astronomers as an Enormous Lyman-Alpha Nebula (ELAN). These types of nebula are massive structures of gas which formed in the early Universe, and they can help astronomers to learn how angular momentum — which explains the observed rotation of more recent galaxies — was created in the Universe. Thanks to the revolutionary MUSE instrument, it is now possible to observe these rare giant nebulae in greater detail than ever before.

This particular ELAN has a diameter of about a million light-years, and MUSE’s spectral imaging capabilities have allowed astronomers to measure the signature of inspiraling motions within the nebula — for the first time ever.

Link

Source: ESO/Potw

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Tuesday, November 21, 2017

Uncovering the Origins of Galaxies' Halos

Figure 1: Eleven dwarf galaxies and two star-containing halos were identified in the outer region of the nearby Whale Galaxy. (Credit: Tohoku University/NAOJ)


Using the Subaru Telescope atop Maunakea, researchers have identified 11 dwarf galaxies and two star-containing halos in the outer region of a large spiral galaxy 25 million light-years away from Earth. The findings, published in The Astrophysical Journal, provide new insight into how these 'tidal stellar streams' form around galaxies.

Researchers from Tohoku University and colleagues used an ultra-wide field of view camera on the Subaru Telescope to develop a better understanding of stellar halos. These ring-shaped collections of stars orbit large galaxies and can often originate from smaller dwarf galaxies nearby.

The team focused their attention on Galaxy NGC 4631, otherwise known as the Whale Galaxy because of its shape. They identified 11 dwarf galaxies in its outer region, some of which were already known. Dwarf galaxies are not easily detected because of their small sizes, masses and low brightness. The team also found two tidal stellar streams orbiting the galaxy: one, called Stream SE, is located in front of it and the other, called Stream NW, is nestled behind it.

Based on calculations aiming to estimate the metallic content of the stellar streams, the team believes it's possible that they originated as a result of a gravitational interaction between the Whale Galaxy and a dwarf galaxy orbiting it.The team focused their attention on Galaxy NGC 4631, otherwise known as the Whale Galaxy because of its shape. They identified 11 dwarf galaxies in its outer region, some of which were already known. Dwarf galaxies are not easily detected because of their small sizes, masses and low brightness. The team also found two tidal stellar streams orbiting the galaxy: one, called Stream SE, is located in front of it and the other, called Stream NW, is nestled behind it.

The team also found that both streams are relatively fainter than other stellar streams that have been studied around galaxies close to the Milky Way. Stream NW is the brighter of the pair, and has a more concentrated core. The researchers hypothesize that this brightness is due to a dwarf galaxy, possibly embedded within it, and that this dwarf had a gravitational interaction with the Whale Galaxy to form Stream SE.

Figure 2: Dwarf galaxies discovered by observation. Three color composites are characterized by HSC-g and HSC-i images. A pseudo-image with intermediate color is created from the averaged image of HSC-g and HSC-i images. The top right column (3) was previously thought to be a dwarf galaxy from an earlier study, but from the high resolution image taken by HSC, it is apparent that what was observed was an overlapping of foreground stars and background galaxies. (Credit: Tohoku University/NAOJ)


It is thought that stellar halos are less common when a galaxy's total stellar mass is smaller than the stellar mass of larger galaxies, such as the Triangulum Galaxy. As a result of their calculations, the researchers believe that the Whale Galaxy, although large, has a smaller mass than the Milky Way. Nonetheless, it is still in an active growth phase, and so are its surrounding halos. Future studies could help further clarify how stellar halos form around galaxies with relatively small masses, the researchers conclude.

This research is published in the Astrophysical Journal (Tanaka et al. 2017, "Resolved Stellar Streams around NGC 4631 from a Subaru/Hyper Suprime-Cam Survey", The Astrophysical Journal, 842, 127).

Link

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Monday, November 20, 2017

ESO Observations Show First Interstellar Asteroid is Like Nothing Seen Before

Artist’s impression of the interstellar asteroid `Oumuamua

Combined deep image of `Oumuamua from the VLT and other telescopes (annotated)

 
The Orbit of ‘Oumuamua

Combined deep image of ‘Oumuamua from the VLT and other telescopes (unannotated)

Artist’s impression of the interstellar asteroid `Oumuamua 

Light curve of interstellar asteroid `Oumuamua


Videos

ESOcast 138 Light: VLT Discovers First Interstellar Asteroid is like Nothing Seen Before (4K UHD)
ESOcast 138 Light: VLT Discovers First Interstellar Asteroid is like Nothing Seen Before (4K UHD)

Animation of `Oumuamua passing through the Solar System
Animation of `Oumuamua passing through the Solar System

Animation of `Oumuamua passing through the Solar System (annotated)
Animation of `Oumuamua passing through the Solar System (annotated)
Animation of artist's concept of `Oumuamua
Animation of artist's concept of `Oumuamua


VLT reveals dark, reddish and highly-elongated object

For the first time ever astronomers have studied an asteroid that has entered the Solar System from interstellar space. Observations from ESO’s Very Large Telescope in Chile and other observatories around the world show that this unique object was traveling through space for millions of years before its chance encounter with our star system. It appears to be a dark, reddish, highly-elongated rocky or high-metal-content object. The new results appear in the journal Nature on 20 November 2017.

On 19 October 2017, the Pan-STARRS 1 telescope in Hawai`i picked up a faint point of light moving across the sky. It initially looked like a typical fast-moving small asteroid, but additional observations over the next couple of days allowed its orbit to be computed fairly accurately. The orbit calculations revealed beyond any doubt that this body did not originate from inside the Solar System, like all other asteroids or comets ever observed, but instead had come from interstellar space. Although originally classified as a comet, observations from ESO and elsewhere revealed no signs of cometary activity after it passed closest to the Sun in September 2017. The object was reclassified as an interstellar asteroid and named 1I/2017 U1 (`Oumuamua) [1].

“We had to act quickly,” explains team member Olivier Hainaut from ESO in Garching, Germany. “`Oumuamua had already passed its closest point to the Sun and was heading back into interstellar space.”

ESO’s Very Large Telescope was immediately called into action to measure the object’s orbit, brightness and colour more accurately than smaller telescopes could achieve. Speed was vital as `Oumuamua was rapidly fading as it headed away from the Sun and past the Earth’s orbit, on its way out of the Solar System. There were more surprises to come.

Combining the images from the FORS instrument on the VLT using four different filters with those of other large telescopes, the team of astronomers led by Karen Meech (Institute for Astronomy, Hawai`i, USA) found that `Oumuamua varies dramatically in brightness by a factor of ten as it spins on its axis every 7.3 hours.

Karen Meech explains the significance: “This unusually large variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape. We also found that it has a dark red colour, similar to objects in the outer Solar System, and confirmed that it is completely inert, without the faintest hint of it.

These properties suggest that `Oumuamua is dense, possibly rocky or with high metal content, lacks significant amounts of water or ice, and that its surface is now dark and reddened due to the effects of irradiation from cosmic rays over millions of years. It is estimated to be at least 400 metres long.

Preliminary orbital calculations suggested that the object had come from the approximate direction of the bright star Vega, in the northern constellation of Lyra. However, even travelling at a breakneck speed of about 95 000 kilometres/hour, it took so long for the interstellar object to make the journey to our Solar System that Vega was not near that position when the asteroid was there about 300 000 years ago. `Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the Solar System.

Astronomers estimate that an interstellar asteroid similar to `Oumuamua passes through the inner Solar System about once per year, but they are faint and hard to spot so have been missed until now. It is only recently that survey telescopes, such as Pan-STARRS, are powerful enough to have a chance to discover them.

“We are continuing to observe this unique object,” concludes Olivier Hainaut, “and we hope to more accurately pin down where it came from and where it is going next on its tour of the galaxy. And now that we have found the first interstellar rock, we are getting ready for the next ones!”


Notes

[1] The Pan-STARRS team’s proposal to name the interstellar objet was accepted by the International Astronomical Union, which is responsible for granting official names to bodies in the Solar System and beyond. The name is Hawaiian and more details are given here. The IAU also created a new class of objects for interstellar asteroids, with this object being the first to receive this designation. The correct forms for referring to this object are now: 1I, 1I/2017 U1, 1I/`Oumuamua and 1I/2017 U1 (`Oumuamua). Note that the character before the O is an okina. So, the name should sound like H O u  mu a mu a. Before the introduction of the new scheme, the object was referred to as A/2017 U1.

More Information

This research was presented in a paper entitled “A brief visit from a red and extremely elongated interstellar asteroid”, by K. Meech et al., to appear in the journal Nature on 20 November 2017.

The team is composed of these J. Meech (Institute for Astronomy, Honolulu, Hawai`i, USA [IfA]) Robert Weryk (IfA), Marco Micheli (ESA SSA-NEO Coordination Centre, Frascati, Italy; INAF–Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy), Jan T. Kleyna (IfA) Olivier Hainaut (ESO, Garching, Germany), Robert Jedicke (IfA) Richard J. Wainscoat (IfA) Kenneth C. Chambers (IfA) Jacqueline V. Keane (IfA), Andreea Petric (IfA), Larry Denneau (IfA), Eugene Magnier (IfA), Mark E. Huber (IfA), Heather Flewelling (IfA), Chris Waters (IfA), Eva Schunova-Lilly (IfA) and Serge Chastel (IfA).

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 and by Australia as a strategic partner. 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 and its world-leading Very Large Telescope Interferometer as well as two survey telescopes, VISTA working in the infrared and the visible-light VLT Survey Telescope. ESO is also a major partner in two facilities on Chajnantor, APEX and ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre Extremely Large Telescope, the ELT, which will become “the world’s biggest eye on the sky”.

Links



Contacts

 Olivier Hainaut
ESO
Garching, Germany
Tel: +49 89 3200 6752

Karen Meech
Institute for Astronomy
Honolulu, Hawai`i, USA
Cell: +1-720-231-7048

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


Source: ESO

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Saturday, November 18, 2017

Astronomers Discover A Star That Would Not Die

Artist’s impression of a Supernova
Credit: NASA/ESA/G. Bacon (STSci)

iPTF14hls ​grew ​bright ​and ​dim ​again ​at ​least ​five ​times ​over ​two ​years. ​This ​behavior ​has ​never ​been seen ​in ​previous ​supernovae, ​which ​typically ​remain ​bright ​for approximately 100 days and ​then fade. Adapted from Arcavi et ​al. 2017, ​Nature. Credit: LCO/S. ​Wilkinson

An image taken ​by ​the ​Palomar ​Observatory ​Sky Survey ​reveals ​a ​possible ​explosion ​in the ​year ​1954 ​at the ​location ​of ​iPTF14hls ​(left), ​not ​seen ​in ​a ​later ​image ​taken ​in ​1993 ​(right). ​Supernovae ​are ​known ​to explode only ​once, ​shine ​for ​a ​few ​months ​and ​then fade, ​but ​iPTF14hls ​experienced ​at ​least ​two explosions, 60 ​years ​apart. Adapted ​from Arcavi et ​al. ​2017, ​Nature.

Lead author Iair​ ​Arcavi,​ ​a​ ​NASA​ ​Einstein​ ​postdoctoral​ ​fellow​ ​at​ ​LCO​ ​and​ ​the​ ​University​ ​of​ ​California Santa​ ​Barbara, visiting the Keck Observatory twin 10-meter optical/infrared telescopes on Maunakea, Hawaii. Credit: I. Arcavi


Maunakea, Hawaii – An international team of astronomers led by Las Cumbres Observatory (LCO) has made a bizarre discovery; a star that refuses to stop shining.

Supernovae, the explosions of stars, have been observed in the thousands and in all cases they marked the death of a star.

But in a study published today in the journal Nature, the team discovered a remarkable exception; a star that exploded multiple times over a period of more than fifty years. Their observations, which include data from W. M. Keck Observatory on Maunakea, Hawaii, are challenging existing theories on these cosmic catastrophes.

“The spectra we obtained at Keck Observatory showed that this supernova looked like nothing we had ever seen before. This, after discovering nearly 5,000 supernovae in the last two decades,” said Peter Nugent, Senior Scientist and Division Deputy for Science Engagement in the Computational Research Division at Lawrence Berkeley National Laboratory who co-authored the study. “While the spectra bear a resemblance to normal hydrogen-rich core-collapse supernova explosions, they grew brighter and dimmer at least five times more slowly, stretching an event which normally lasts 100 days to over two years.”

Researchers used the Low Resolution Imaging Spectrometer (LRIS) on the Keck I telescope to obtain spectrum of the star’s host galaxy, and the Deep Imaging and Multi-Object Spectrograph (DEIMOS) on Keck II to obtain high-resolution spectra of the unusual star itself.

The supernova, named iPTF14hls, was discovered in September of 2014 by the Palomar Transient Factory. At the time, it looked like an ordinary supernova. Several months later, LCO astronomers noticed the supernova was growing brighter again after it had faded.

When astronomers went back and looked at archival data, they were astonished to find evidence of an explosion in 1954 at the same location. This star somehow survived that explosion and exploded again in 2014.

“This supernova breaks everything we thought we knew about how they work. It’s the biggest puzzle I’ve encountered in almost a decade of studying stellar explosions,” said lead author Iair Arcavi, a NASA Einstein postdoctoral fellow at LCO and the University of California Santa Barbara.

The study calculated that the star that exploded was at least 50 times more massive than the sun and probably much larger. Supernova iPTF14hls may have been the most massive stellar explosion ever seen. The size of this explosion could be the reason that our conventional understanding of the death of stars failed to explain this event.

Supernova iPTF14hls may be the first example of a “Pulsational Pair Instability Supernova.”

“According to this theory, it is possible that this was the result of star so massive and hot that it generated antimatter in its core,” said co-author Daniel Kasen, an associate professor in the Physics and Astronomy Departments at UC Berkeley and a scientist at Lawrence Berkeley Lab. “That would cause the star to go violently unstable, and undergo repeated bright eruptions over periods of years.”

That process may even repeat over decades before the star’s large final explosion and collapse to a black hole.

“These explosions were only expected to be seen in the early universe and should be extinct today. This is like finding a dinosaur still alive today. If you found one, you would question whether it truly was a dinosaur,” said Andy Howell, leader of the LCO supernova group and co-author of the study.

Indeed, the “Pulsational Pair Instability” theory may not fully explain all the data obtained for this event. For example, the energy released by the supernova is more than the theory predicts. This supernova may be something completely new.

Astronomers continue to monitor iPTF14hls, which remains bright three years after it was discovered.

“This is one of those head-scratcher type of events,” said Nugent. “At first we thought it was completely normal and boring. Then it just kept staying bright, and not changing, for month after month. Piecing it all together, from our observations at Palomar Transient Factory, Keck Observatory, LCOGT, and even the images from 1954 in the Palomar Sky Survey, has started to shed light on what this could be. I would really like to find another one like this.”


Media Contact:

 Mari-Ela Chock, Communications Officer
mchock@keck.hawaii.edu
(808) 554-0567




About W.M. Keck Observatory

The W. M. Keck Observatory telescopes are among the most scientifically productive on Earth. The two, 10-meter optical/infrared telescopes on the summit of Maunakea on the Island of Hawaii feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectrometers, and world-leading laser guide star adaptive optics systems.

Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c) 3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.
The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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