Massive twin star discovered snuggling close to its stellar sibling

University of Leeds

2MASS observations (background image) revealed a highly reddened source back in 2003 indicating the massive young nature of PDS 27. PIONIER on VLTI provides 2,000 times higher angular resolution making it possible to resolve PDS 27 as a binary system for the first time in 2019. Credit Evgenia Koumpia, University of Leeds

Astronomers have discovered a binary star system with the closest high-mass young stellar objects ever measured, providing a valuable “laboratory” to test theories on high mass binary star formation.

An international team led by the University of Leeds has determined the distance between the massive young star PDS 27 and its orbiting stellar companion to be just 30 astronomical units away or 4.5 billion km. That is roughly the distance between our Sun and Neptune, making them the stellar companions with the closest proximity ever determined for young high mass stars in a binary system – a star system with two stars in orbit around a centre of mass.

Study lead author, Dr Evgenia Koumpia, from the School of Physics and Astronomy at Leeds, said: “This is a very exciting discovery, observing and simulating massive binaries at the early stages of their formation is one of the main struggles of modern astronomy. With PDS 27 and its companion we have now found the closest, most massive young stellar objects in binaries resolved to date.

“There is a shortage of known young massive binary systems in charted space. High mass stars have comparatively short lifespans, burning out and exploding as supernovae in only a few million years, making them difficult to spot. This limits our ability to test the theories on how these stars form.”

As part of their study the team has also identified a companion object for another young massive star referred to as PDS 37. The analysis revealed a distance between PDS 37 and its companion to be between 42 to 54 astronomical units -comparable to the distance between the Sun and Pluto. While further apart than PDS 27 and its companion, it is still a significant discovery given the need for confirmed massive young stellar binaries in astronomical research.

Dr Koumpia continued: “How these binary systems form is quite a controversial question with several theories having been put forward. Observational studies of binaries in their early stages are crucial to verifying the theories of their formation.

“PDS 27 and PDS 37 are rare and important laboratories that can help inform and test the theories on the formation of high mass binaries.”

PDS 27 is at least 10 times more massive than our Sun, Dr Koumpia explained, and about 8,000 light years away. To determine the presence of stellar companions for PDS 27 and PDS 37, the team used the highest spatial resolution provided by the PIONIER instrument on the European Southern Observatory’s Very Large Telescope Interferometer (VLTI). This instrument combines light beams from four telescopes, each of which is 8.2 metres across, and mimics a single telescope with a diameter of 130m. The resulting high spatial resolving power allowed the team to resolve such close binary systems despite their huge distance from us and their close proximity to each other.

Study co-author Professor Rene Oudmaijer, also from the School of Physics and Astronomy at Leeds, said: “The next big question – which we have tended to avoid so far because of observational difficulties – is why so many of these massive stars are in binary systems?”

“It has become increasingly clear to astronomers that massive stars are almost never born alone, with at least one sibling for company. But the reasons why that is the case are still rather murky.

“Massive stars exert significant influence on their cosmic environment. Their stellar winds, energy and the supernova explosions they generate in turn can impact the formation of other stars and galaxies. The evolution and fate of high-mass stars is quite complex but previous studies have shown that they can be influenced to a large degree by their binary properties.

“The discovery of massive young binary stars provides a crucial step forward in being able to answer many of the questions we still have about these stellar objects. These discoveries were only possible thanks to the exquisite resolving power provided by the PIONIER instrument on the VLTI.”

This research is published in the journal Astronomy & Astrophysics: Letters.


Further information:

The study “Resolving the MYSO binaries PDS 27 and PDS 37 with VLTI/PIONIER” is published in Astronomy & Astrophysics: Letters 11 March 2019 (DOI: 10.1051/0004-6361/201834624)

Full list of authors: E. Koumpia, K. M. Ababakr, W. J. de Wit, R. D. Oudmaijer, A. Caratti o Garatti, P. Boley, H. Linz, S. Kraus, J. S. Vink, J.-B Le Bouquin

Further information relating to PIONIER can be found on the ESO website.


PDS27 (attached)
Caption: 2MASS observations (background image) revealed a highly reddened source back in 2003 indicating the massive young nature of PDS 27. PIONIER on VLTI provides 2000 times higher angular resolution making it possible to resolve PDS 27 as a binary system for the first time in 2019.
Credit: Evgenia Koumpia, University of Leeds

Binary formation figure (recommended image, available for download:
An artistic view illustrating one of the main theories on how orbiting pair stars form. A young star is surrounded by a rotating disk of gas and dust, with its companion forming within the fragmenting disk.
Credit: B. Saxton, NRAO/AUI/NSF

VLT Unit Telescopes (recommended image, available for download:
All four VLT Unit Telescopes working as one
Credit: G.Hüdepohl (

The PIONEIR instrument (recommended image, available for download:
Credit: ESO & B. Lazareff (LAOG)

Acknowledgements: S.K. acknowledges support from an ERC Starting Grant (Grant Agreement No. 639889). A.C.G. has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 743029).

University of Leeds

The University of Leeds is one of the largest higher education institutions in the UK, with more than 38,000 students from more than 150 different countries, and a member of the Russell Group of research-intensive universities. The University plays a significant role in the Turing, Rosalind Franklin and Royce Institutes.

We are a top ten university for research and impact power in the UK, according to the 2014 Research Excellence Framework, and are in the top 100 of the QS World University Rankings 2019.

The University was awarded a Gold rating by the Government’s Teaching Excellence Framework in 2017, recognising its ‘consistently outstanding’ teaching and learning provision. Twenty-six of our academics have been awarded National Teaching Fellowships – more than any other institution in England, Northern Ireland and Wales – reflecting the excellence of our teaching.

About DIAS

Dr Alessio Caratti o Garatti is a researcher from the School of Astronomy and Astrophysics at the Dublin Institute for Advanced Studies (DIAS). As the world’s second, and Ireland’s only, Institute for Advanced Studies, DIAS is a globally embedded institution that attracts scholars and academics from around the world. It conducts and publishes advanced research across three disciplines: Celtic Studies, Theoretical Physics and Cosmic Physics (encompassing Astronomy, Astrophysics and Geophysics). DIAS also leads Ireland’s participation in a number of international research endeavours that focus on big unanswered questions for mankind. Further information is available at

Follow DIAS on social media:

Max Planck Institute for Astronomy (MPIA)

The Max Planck Institute for Astronomy (MPIA) in Heidelberg is an institute of the Max Planck Society, Germany’s largest organization for fundamental research. The two science departments at MPIA address cardinal questions of cosmic evolution: How do stars and planets form, and what can we learn about planets orbiting stars other than the Sun?

How do galaxies form, and how have they changed in the course of cosmic history? Furthermore, MPIA hosts a versatile instrumentation department that is involved in building cutting-edge instruments for the VLT(I), LBT, and the E-ELT, as well as for space-borne missions like JWST, EUCLID, and WFIRST. | @mpi_astro

Public Release: 11-Mar-2019

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Mark - Helsinki
March 12, 2019 4:15 am

Ugh science media,

We have no idea how old any star is, even our own, it’s pure hokum to even suggest we even have an idea about a guess about having an idea.

By all means find and observe these astronomical objects, but the big bang is religion and inflation theory is junk science.

Reply to  Mark - Helsinki
March 12, 2019 9:09 am

The microwave “fog” from the supposed big bang is supposedly 13.7 billion years old, supposedly something happened.13.7 billion years ago. Cosmologists studying the acoustics of this supposed happening theorize, some of them, that those acoustics indicate that the universe is infinite and probably eternal so, whatever happened 13.7 billion years ago was not the beginning of time or the universe, supposedly. Consensus science, however, rules. And saying “maybe” is verboden.

Reply to  Mark - Helsinki
March 12, 2019 10:06 am

I don’t know about you, but I have a pretty good guess on the age. It is more than the Earth’s, billions of years.

What comes to bangs, details are sketchy but it is still much better a theory than the old ‘somebody just made the world up say 6kyrs ago’. 6k is off by a factor of 2 million. And the who part – there are no whos without a world in the first place.

Reply to  Hugs
March 12, 2019 11:38 am

Really? So someone who is eternal (and could “speak” the universe into existence”) couldn’t give the universe an appearance of age? Not that I am disagreeing with you. Just pointing out flaws in your reasoning.

Reply to  F.LEGHORN
March 12, 2019 1:16 pm

Sure, pal. Maybe the world popped into existence yesterday by the mighty eternal spaghetti monster, who, being eternal and living in its own metaworld, has thought all thoughts possible and will think them again, and because of that, will create all possible and impossible worlds over and over again.

Just pointing a flaw in your logic.

A god of holes is not worth it. Either you use observation, experiment, mathematics and logic, or you don’t. If you don’t want to use them, the modern life will appear pretty random. You know, your iPhone doesn’t work because it obeys the physical laws we know, but rather because a god decided to let that happen. You couldn’t prove I’m wrong.

And because of exactly that and the certain persistency of antibigbangers here, I will now retreat. Claim your victory if you will.

Joel O'Bryan
Reply to  Mark - Helsinki
March 12, 2019 11:44 am

Please leave the stellar physics and astrophysics to astrophysicists. Stick to your religion and Noah’s Ark theories.

We know to a very close number the age of our sun.
Multiple lines of evidence arrives at the following figures:
Our sun today is 4.57 (+/- 0.01) Billion years old. It took about 10 million years to collapse under gravity out of cold molecular hydrogen gas cloud. Another 40 million years to ignite fusion, increase luminosity and enter the Main Sequence. It has been on the Main Sequence for about 4.52 Billion years now.

Models of stellar evolution have been verified repeatedly by many independent lines of evidence, by groups with independent observations trying to poke holes in and refine the existing models. They work.

As for the Big Bang and Inflation, yes those are theories, but that so far the evidence such as the Cosmic Microwave background evidence supports something like that happened. Knowing something happened is not anywhere near the same as understanding why or the underlying physics.

A more Earthly example is the extinction of the dinosaurs around 66 My ago. We they went bye-bye in the blink of a geological eye time-wise. Why they went bye-bye is of course still debated by many diverse theories and evidence. Meteorite-bolide impact, volcanism shutting out the sunlight, Earth getting too cold, viruses, on and on.

Reply to  Joel O'Bryan
March 12, 2019 1:27 pm

Yes Joel!

If a person doesn’t want to take science seriously, climate scientists and their university press offices do give a lot to doubt.

At the same time it is, for a layman, very difficult to know what kind of uncertainty the age of the Sun or say, dark matter theories include.

The age of the Sun is well-known. The composition of the anomaly dubbed dark matter is very poorly understood. However, religion should keep out of cosmology.

The shortcomings of ‘popular climate science’ are much more comprehensible, though many features like the efficacy of four parts in ten thousand tend to be unintuitive.

Peter Parke
Reply to  Mark - Helsinki
March 12, 2019 4:16 pm

Thank you, Mark:

Why do people forget that science is here and now? Were they there? With respect to us, Mars, the moon,etc., light, even from distant stars, moves at the speed of light. So, with respect to us, time does not advance on that photon of light, so the beam is telling us what is happening even we see it. Of course, for us to communicate with a binary star, 8000 light years away, which is with respect to us, is moving very much slower than “c”, will indeed take 16,000 years to be received, answered, and that answer to be received.

As Job was asked, in so many different ways, “Where were YOU when I laid the foundations of the earth?”.


old construction worker
March 12, 2019 4:33 am

‘a star system with two stars in orbit around a centre of mass.’ A center mass of what? A small black hole? Dark matter? What?

Reply to  old construction worker
March 12, 2019 4:48 am

Layman’s take on that: like a rotating bolo, where gravity is the tether and the centre point of the rotation is the balance point of the combined masses.

Reply to  old construction worker
March 12, 2019 4:58 am

Center of their combined mass, OCW. There is nothing necessarily there. That is how any system of two or more gravitationally bound objects behave.

Even in our own Solar system, the center of the system is not the center of the Sun. The center of mass happens to be inside the Sun, but even the mass of the Sun orbits around that center. It’s a rather complex curve, but the most interesting bit is that when Jupiter is on our side (conjunction), the Sun is closer to us, and further away when Jupiter is on the other side (opposition).

Reply to  Writing Observer
March 12, 2019 5:00 am

Aaargh! Read that last bit, looked right at it, and hit post anyway. It’s the OTHER way around – the Sun is closer to us when Jupiter is in OPPOSITION.

Sigh, I miss edit most on those mornings when the caffeine hasn’t yet kicked in.

Michael S. Kelly LS, BSA Ret.
Reply to  old construction worker
March 12, 2019 5:18 am

Take two uniform density spheres, and place them in space. Establish an axis passing through the geometric center of both. Then pick a point anywhere on that axis, and label it “zero.” Take the distance from this zero to each of the centers of mass of the spheres, and multiply each by the mass of the sphere corresponding to that distance. Sum those two numbers, then divide by the sum of the two masses. The result will be the location of the center of mass of the pair of spheres with respect to the arbitrarily selected point zero.

This can be extended to three dimensions, and particles of any size.

Steve Reddish
Reply to  Michael S. Kelly LS, BSA Ret.
March 12, 2019 8:41 pm

“2 uniform density spheres”…Do these actually exist? Planets have dense cores inside “lighter” mantles. Stars have a density gradient – density is greatest at the center.

“Take the distance from this zero to each of the centers of mass of the spheres”…You must already know exactly the spacing between the 2 spheres.

“multiply each by the mass of the sphere corresponding to that distance”…You also know exactly the mass of each sphere? How? Has even 1 revolution been observed?

I don’t think you are describing the circumstances or the difficulties these astronomers are dealing with.


Crispin in Waterloo
Reply to  old construction worker
March 12, 2019 6:06 am

Old construction worker

The point about which they orbit is called the barycentre. The barycentre of the Earth-Moon system is 1000 km below the Earth’s surface on the side facing the moon at the time. After 12 hrs, it is 1000 km below the surface on the opposite side of the planet. This “massages” the Earth creating heat and crustal movement up and down.

The barycentre of the solar system is sometimes deep inside the sun, and sometimes outside, depending on the distribution of the large planets. The rate of change of the position of the sun’s centre relative to the outside diameter is considered by some to be a driver of solar activity, which in turn affects the climate on Earth. This rate of change in the position is colloquially called the Solar Jerk. When the rate of change is high, the sun is quite active, as has been the case in recent decades. We are now entering a period during which the barycentre is well inside the sun and solar activity is anticipated to be low.

It is well known that planets have beat frequencies and that there are coincident cycles in or on the sun. Whether or not these are causative provokes a lively debate. It is used by some to make long term predictions of terrestrial events such as droughts and El Niños. In general the topic of barycentric solar influence is a topic not permitted on this site.

Reply to  Crispin in Waterloo
March 12, 2019 7:16 am

What if it turns out (not saying it is) that barycentric solar influence is the cause of some short term climate change via sunspots and other electromagnetic effects caused by such, and we were prohibited all this time from discussing or mentioning it here? Barycentric orbital mechanics are a fact, whether they have any influence should be a matter of investigation. That would seem very unfair and unscientific that we can’t mention this ‘taboo’ subject…maybe time for an update on this kind of subject matter, as long as it remains in the realm of scientific relevancy?

Reply to  old construction worker
March 12, 2019 4:11 pm

old construction worker
March 12, 2019 at 4:33 am

‘a star system with two stars in orbit around a centre of mass.’

It’s probably a typo. The correct phrase is usually “common center of mass.” Sometimes you see the term “centroid.” A centroid usually ignores any variation in density, therefore the centroid and center of gravity may not always coincide. Astronomers generally use the term “barycenter” for the common center of gravity of orbiting objects such as planets, moons, stars, etc.


March 12, 2019 6:32 am

If Jupiter was 75-100 times bigger, we would be in a binary star system.

Steve Reddish
Reply to  rbabcock
March 12, 2019 8:44 pm

That is a lot of “if”.

March 12, 2019 7:54 am

“It has become increasingly clear to astronomers that massive stars are almost never born alone, with at least one sibling for company. But the reasons why that is the case are still rather murky.”

Seems as though this is always the case with new observations. We know much less than we think we do. ” It ain’t all the things we don’t know but all the things we do know which just ain’t so. ” Samuel Clemens

March 12, 2019 8:25 am

That is odd because gravitational eliptical orbits have 2 centers.
Why is it emphasized as “very reddened” ? Are both objects reddened?

Curious George
Reply to  bonbon
March 12, 2019 12:18 pm

A gravitational redshift allows us to estimate a star’s mass.

ferd berple
March 12, 2019 11:33 am

massive stars are almost never born alone
Which flies in the face of the standard model of solar system formation.

Almost completely ignored is the near integer harmonics of our own solar system. Being regarded as due to simple coincidence.

Look at a log afloat on the ocean. It invariably turns broadside to the waves. Is this also coincidence.

All too often we think in terms of forcing, cause and effect. How then do you explain the chicken and egg.

nature favors cycles over simply cause and effect, due to the effects of time on the observer. If something happens only once, the odds are that you will never see it.

But what makes a cycle stable.

Joel O'Bryan
Reply to  ferd berple
March 12, 2019 11:52 am

At the most fundamental level, cycles in physical systems and their decay (change) occur because of the 1st, 2nd and 3rd Laws of Thermodynamics.

Curious George
Reply to  Joel O'Bryan
March 12, 2019 12:21 pm

I thought it was the Law of Gravitation?

Steve Reddish
Reply to  ferd berple
March 12, 2019 9:18 pm

“Which flies in the face of the standard model of solar system formation.”

Could somebody tell me how the standard model explains the 1st stage of the accretion process: what makes dust grains stick to each other? Why a cluster of grains, if struck by another cluster, doesn’t get scattered? Initially, no cluster of grains would have enough gravity to have an escape velocity high enough to keep the cluster together.

But first, please explain how the elements in a molecular cloud combined to form dust grains.

Also tell me why stars seem to defy the law of conservation of rotation energy.

And finally, if planetesimals did form, how was it they didn’t spiral into the sun?

Steve Reddish
Reply to  Steve Reddish
March 12, 2019 9:53 pm

One more question:
Those dust grains were the result of earlier stars going nova, spewing out elements heavier than lithium. Prior novas also provided shock waves that compressed hydrogen in a molecular cloud enough to initiate gravitational collapse of 2nd generation stars.

What initiated the collapse of the first generation of stars?


March 13, 2019 6:00 pm

I wonder if they can detect any visible tendrils between the two close-by binary stars. And do they have the same or different redshifts?

The late Halton Arp would certainly be interested in the answers.

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