Category Archives: ESO

Proxima Centuri’s Orbit


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


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


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


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


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


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.

ESO/P. Kervella

The Boomerang Nebula


This image is the Boomerang Nebula, a product of ALMA and Hubble. The Boomerang is 5,000 light-years away in the constellation Centaurus. Click the image above to see the Hubble image without the ALMA data, you will also see why it also has the name of the Bow Tie Nebula.

The Boomerang is a protoplanetary nebula, a confusing term because it does not mean it is forming planets, it’s between the (asymptotic) giant phase and the planetary nebula phase. The cool thing about the Boomerang is not just cool it is cold. It is the coldest place we know of, 1 degree Kelvin and that’s -272.15 C / -457.87 F, the atoms are just barely moving!

I also can’t help thinking I saw an episode of Star Trek with a creature that looks a lot like the ALMA addition.

Image: Bill Saxton; NRAO/AUI/NSF; NASA/Hubble; Raghvendra Sahai

The Medusa


Astronomers used the ESO’s Very large Telescope in Chile took this “most detailed” image of the Medusa Nebula.

The colorful nebula cloud is from the the central star that has puffed off its outer layers, just like our Sun will do far in the future.

This nebula is off the “knee” of Pollux in the Gemini constellation. The ESO team put out a wide-field view that is amazingly good and more inline with what you would see in a telescope although way-way better of course. (Credit: ESO/Digitized Sky Survey 2) It in my opinion pretty hard to see, at least it was for me and my scope.

Want a desktop of this image and much higher resolution images in general? Go here to visit the ESO page.