Category Archives: ESO

ALMA and Solar Science

Global cooperation is the hallmark of ALMA and much of science for that matter. The ALMA Solar campaign is one of the most diverse, take a look below the fold at the end of the press release.

This image of an enormous sunspot was taken on 18 December 2015 with the Band 6 receiver at a wavelength of 1.25 millimeters.

ALMA Reveals Sun in New Light

New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot that is nearly twice the diameter of the Earth.

These images are part of the testing and verification campaign to make ALMA’s solar observing capabilities available to the international astronomical community.

Though designed principally to observe remarkably faint objects throughout the universe — such as distant galaxies and planet-forming disks around young stars – ALMA is also capable of studying objects in our own solar system, including planets, comets, and now the Sun.

During a 30-month period beginning in 2014, an international team of astronomers harnessed ALMA’s single-antenna and array capabilities to detect and image the millimeter-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, the visible surface of the Sun.

These new images demonstrate ALMA’s ability to study solar activity at longer wavelengths than observed with typical solar telescopes on Earth, and are an important expansion of the range of observations that can be used to probe the physics of our nearest star.

“We’re accustomed to seeing how our Sun appears in visible light, but that can only tell us so much about the dynamic surface and energetic atmosphere of our nearest star,” said Tim Bastian, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Va. “To fully understand the Sun, we need to study it across the entire electromagnetic spectrum, including the millimeter and submillimeter portion that ALMA can observe.”

Since our Sun is many billions of times brighter than the faint objects ALMA typically observes, the solar commissioning team had to developed special procedures to enable ALMA to safely image the Sun.

The result of this work is a series of images that demonstrates ALMA’s unique vision and ability to study our Sun on multiple scales.

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

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Active Galactic Nucleus

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The galaxy above called IC-3639 has an Active Galactic Nucleus that is actually obscured which leads to even more questions.  AGN’s are super-massive black holes (in the order of a million to probably hundreds of million solar masses) that are accreting massive amounts of matter, which is to say “feeding”. The accretion disc makes the Active Galaxies among the brightest objects in terms of electromagnetic radiation, so bright it is not often whether or not a galaxy is active, is in question, IC 3639 is such a galaxy.

A word about black holes in general because some people have a mistaken impression of black holes as marauding monsters roaming the universe looking for innocent planets to swallow up, that just came up on an outing with friends. No, a black holes don’t really do that. In fact if you took a black hole of one-solar-mass and swapped it with our Sun our solar system would just keep right on going just like it does now, aside from light and heat of course, the fabric of space-time would be just as it is now.

From NuSTAR:
IC 3639, a galaxy with an active galactic nucleus, is seen in this image combining data from the Hubble Space Telescope and the European Southern Observatory.

This galaxy contains an example of a supermassive black hole hidden by gas and dust. Researchers analyzed NuSTAR data from this object and compared them with previous observations from NASA’s Chandra X-Ray Observatory and the Japanese-led Suzaku satellite. The findings from NuSTAR, which is more sensitive to higher energy X-rays than these observatories, confirm the nature of IC 3639 as an active galactic nucleus that is heavily obscured, and intrinsically much brighter than observed.

NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

Image and caption: NASA/JPL-Caltech/ESO/STScI

Proxima Centuri’s Orbit

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Credit:  P. Kervella (CNRS/U. of Chile/Observatoire de Paris/LESIA), ESO/Digitized Sky Survey 2, D. De Martin/M. Zamani

From the ESO:

Interest in our neighbouring Alpha Centauri star system has been particularly high since the recent discovery of an Earth-mass planet, known as Proxima b, orbiting the system’s third star — and the closest star to the Sun — Proxima Centauri. While the system’s larger stellar pair, Alpha Centauri A and B, appear to have a proper motion on the sky that is very similar to that of the smaller, fainter Proxima Centauri, it has not been possible to demonstrate that the three stars do actually form a single, gravitationally bound, triple system.

Now three astronomers, Pierre Kervella, Frédéric Thévenin and Christophe Lovis, have concluded that the three stars do indeed form a bound system. In the century since it was discovered, Proxima Centauri’s faintness has made it extremely difficult to reliably measure its radial velocity — the speed at which it moves towards and away from Earth. But now ESO’s planet-hunting HARPS instrument has provided an extremely precise measurement of Proxima Centauri’s radial velocity, and even greater accuracy has been achieved by accounting for other subtle effects [1].

As a result, the astronomers have been able to deduce very similar values for the radial velocities of the Alpha Centauri pair and Proxima Centauri, lending credence to the idea that they form a bound system. Taking account of these new measurements, calculations of the orbits of the three stars indicate that the relative velocity between Proxima Centauri and the Alpha Centauri pair is well below the threshold above which the three stars would not be bound together by gravity.

This result has significant implications for our understanding of the Alpha Centauri system and the formation of planets there. It strongly suggests that Proxima Centauri and the Alpha Centauri pair are the same age (about 6 billion years), and that in turn provides a good estimate of the age of the orbiting planet, Proxima b.

The astronomers speculate that the planet may have formed around Proxima Centauri on a more extended orbit and then been brought to its current position, very close to its parent star, as a result of the close passage of Proxima Centauri to its cousins in the Alpha Centauri pair. Alternatively, the planet may have formed around the Alpha Centauri pair, and was later captured by the gravity of Proxima Centauri. If one of these hypotheses is correct, it is possible that the planet was once an icy world that underwent a meltdown and now has liquid water on its surface.

A Real Goldilocks Planet

WOW!  Pretty excellent work from the ESO!

A review of the data from shows  tiny Doppler shifts indicate the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting around Proxima Centauri and just 7 million kilometres/ 4.3 million miles and that’s  only 5% of the Earth-Sun distance.  The orbital period (that’s a year) of the planet is 11.2 DAYS!

Yes, for Proxima Centauri that is still in the habitable zone.  Proxima Centauri is around 8.25 light-years away far enough to make further investigation difficult.

Difficult is not impossible. . . stay tuned,  as they say on the television.

ESO Video

Making a Brown Dwarf

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When I think of a brown dwarf I think of a stellar body that doesn’t have quite enough mass to become a full fledged star.  Now it seems there is an example of a brown dwarf being formed because a companion has taken so much mass from a regular star it has actually been downgraded according to researchers.

From SpaceRef:
Astronomers have detected a sub-stellar object that used to be a star, after being consumed by its white dwarf companion.

An international team of astronomers made the discovery by observing a very faint binary system, J1433 which is located 730 light-years away. The system consists of a low-mass object – about 60 times the mass of Jupiter – in an extremely tight 78-minute orbit around a white dwarf (the remnant of a star like our Sun).

Due to their close proximity, the white dwarf strips mass from its low-mass companion. This process has removed about 90 per cent of the mass of the companion, turning it from a star into a brown dwarf.

Most brown dwarfs are ‘failed stars’, objects that were born with too little mass to shine brightly by fusing hydrogen in their cores. By contrast, the brown dwarf in this system was born as a full-fledged star, but has been stripped to its current mass by billions of years of stellar cannibalism.
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A Stellar Baby Blankey

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The ESO has been busy!

Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) have made the first direct observations delineating the gas disk around a baby star from the infalling gas envelope. This finding fills an important missing piece in our understanding of the early phases of stellar evolution.

A research team, led by Yusuke Aso (a graduate student at the University of Tokyo) and Nagayoshi Ohashi (a professor at the Subaru Telescope, National Astronomical Observatory of Japan) observed the baby star named TMC-1A, which is located 450 light-years from Earth in the constellation Taurus. TMC-1A is a protostar, a star still in the process of forming.

The team directly observed the boundary between the inner rotating disk and the outer infalling envelope. Since gas from the outer envelope is continuously falling into the disk, it had been difficult to identify the transition region in previous studies. In particular, the tenuous but high-speed gas in rotating disks is not easy to see. But ALMA has enough sensitivity to highlight such a component and illustrate the speed and distribution of gas in the disk very precisely. This enabled the team to distinguish the disk from the infalling envelope.

Read the full text of NAOJ’s release here.

Reflection Nebula

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A reflection nebula is an interstellar dust cloud that is reflecting light from a nearby star. In this case, a young star is lighting up IC2631 and is shown by this great image from the ESO.

A newly formed star lights up the surrounding cosmic clouds in this image from ESO’s La Silla Observatory in Chile. Dust particles in the vast clouds that surround the star HD 97300 diffuse its light, like a car headlight in enveloping fog, and create the reflection nebula IC 2631. Although HD 97300 is in the spotlight for now, the very dust that makes it so hard to miss heralds the birth of additional, potentially scene-stealing, future stars.

Credit: ESO

First Light for GRAVITY

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WOW!  Look just look at the results from the first light of the GRAVITY instrument, which essentially takes light gathered from multiple telescopes and combines it into a single image.

The caption released with the image:

As part of the first observations with the new GRAVITY instrument the team looked closely at the bright, young stars known as the Trapezium Cluster, located in the heart of the Orion star-forming region. Already, from these first data, GRAVITY made a discovery: one of the components of the cluster (Theta1 Orionis F, lower left) was found to be a double star for the first time. The brighter double star Theta1 Orionis C (lower right) is also well seen.

The background image comes from the ISAAC instrument on ESO’s Very Large Telescope. The views of two of the stars from GRAVITY, shown as inserts, reveal far finer detail than could be detected with the NASA/ESA Hubble Space Telescope.

Credit: ESO/GRAVITY consortium/NASA/ESA/M. McCaughrean

Get a more detailed description here at the ESO, it’s well worth your time.

You can also get large versions of the image at this ESO page.

ESO’s New Gear

butterfly2

The SPHERE instrument was recently installed on the VLT at ESO’s Paranal Observatory. The Spectro-Polarimetric High-contrast Exoplanet REsearch instrument or SPHERE for short was installed on Unit Telescope 3 of the VLT.

SPHERE is a very sophisticated instrument designed to spot exo-planets by direct imaging. SHPERE will have the ability to block out the central part of a given star to reduce its contribution. To make this very basic, the light coming from stars (including our sun) is not polarized but when that light is reflected off an exo-planet it becomes at least partially polarized and SHPERE can pick out the polarized signal. For a bit more detailed explanation look here.

From ESO:
Some of the sharpest images ever made with ESO’s Very Large Telescope have for the first time revealed what appears to be an ageing star in the early stages of forming a butterfly-like planetary nebula. The observations of the red giant star L2 Puppis from the ZIMPOL mode of the newly installed SPHERE instrument are combined here with infrared data from NACO, also on the VLT, which shows a dust loop deployed on the far side of the upper part of the nebula. The dying stages of the lives of stars continue to pose many riddles for astronomers.

Credit:
ESO/P. Kervella