Making stars when the universe was half its age

January 18, 2019, Harvard-Smithsonian Center for Astrophysics
The Hubble Ultra Deep Field of galaxies. A new study of the star formation activity in 179 of the galaxies in this image including many dating from about six billion years ago confirms an earlier puzzling result: lower mass galaxies tend to make stars at a rate slightly slower than expected. Credit: NASA, ESA, and S. Beckwith (STScI) and the HUDF Team

The universe is about 13.8 billion years old, and its stars are arguably its most momentous handiwork. Astronomers studying the intricacies of star formation across cosmic time are trying to understand whether stars and the processes that produce them were the same when the universe was younger, about half its current age. They already know that from three to six billion years after the big bang stars were being made at a rate roughly ten times faster than they are today. How this happened, and why, are some of the key questions being posed for the next decade of research.

Star formation in a galaxy is thought to be triggered by the accretion of gas from the intergalactic medium (gas accretion via mergers between is thought to play a relatively minor role in the total numbers of produced). In galaxies that are actively making stars there is a tight relationship between their mass in stars and their rate of forming new stars, and this relationship approximately holds not only locally but even back when the universe was billions of years younger. In contrast, galaxies that are undergoing an active starburst—or the opposite, the quenching of star formation—fall above and below that relation respectively. The relationship supports the general picture of galaxy growth by gas accretion, except that for some reason smaller galaxies – those with fewer than about ten billion stars – seem to make slighter fewer stars than expected for their masses (the Milky Way is right at the turnover, with about ten billion stars and a rate of roughly one new star per year). A particularly significant consequence of this paucity, if real, is that simulations of galaxy growth do not show it, implying that the simulations are incorrect for smaller galaxies and that some physics is missing.

CfA astronomer Sandro Tacchella is a member of a team that used the Multi Unit Spectroscopic Explorer instrument on the VLT (Very Large Telescope) to obtain optical spectra of galaxies in the famous Hubble Deep Field South image of galaxies. They measured stellar emission lines in 179 distant galaxies in the field and used them to calculate the star formation behaviors after corrections for effects like dust extinction (which can make some of the optical lines appear weaker than they are). The find that the puzzle of depleted in small galaxies is real at a level of roughly 5% even when accounting for noise and scatter in the data caused, for example, by galaxy evolution effects. The authors suggest that some kind of previously unaccounted for feedback may be responsible.

Explore further: Image: Hubble finds smiling face in a hunt for newborn stars

More information: Leindert A. Boogaard et al. The MUSE Hubble Ultra Deep Field Survey, Astronomy & Astrophysics (2018). DOI: 10.1051/0004-6361/201833136

Related Stories

Image: Hubble finds smiling face in a hunt for newborn stars

November 5, 2018

This image, taken with the NASA/ESA Hubble Space Telescope's Wide Field Camera 3 (WFC3), shows a patch of space filled with galaxies of all shapes, colors and sizes, many of which belong to the galaxy cluster SDSS J0952+3434.

How disc galaxies work

July 23, 2018

Disc galaxies like our own Milky Way, characterized by a flattened disc of stars and gas (often with a central bulge of material as well) have a wide range of masses, spatial extents, and stellar content. Nonetheless all ...

Image: Hubble's compact galaxy with big-time star formation

October 16, 2017

As far as galaxies are concerned, size can be deceptive. Some of the largest galaxies in the Universe are dormant, while some dwarf galaxies, such as ESO 553-46 imaged here by the NASA/ESA Hubble Space Telescope, can produce ...

Understanding star-forming galaxies

June 5, 2017

The more stars a typical spiral galaxy contains, the faster it makes new ones. Astronomers call this relatively tight correlation the "galaxy main sequence." The main sequence might be due simply to the fact that galaxies ...

A massive galaxy long ago and far away

February 6, 2017

Galaxies today fall roughly into two categories: elliptically-shaped collections of reddish, old stars that formed predominantly during a period early in the history of the universe, and spiral shaped objects dominated by ...

Image: Hubble's cosmic atlas

July 28, 2017

This beautiful clump of glowing gas, dark dust and glittering stars is the spiral galaxy NGC 4248, located about 24 million light-years away in the constellation of Canes Venatici (The Hunting Dogs).

Recommended for you

35 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

rrwillsj
2.5 / 5 (2) Jan 18, 2019
Well, the only phenomena that is a constant over tens of billions of years is Gravity. It is not exhausted by Time or any other activity.

As long as the base gravitrons stick together? None of the other Forces really matter.

Except to sophonts who enjoy looking up into their sky at night & seeing the pretty sparkles.
valeriy_polulyakh
2.3 / 5 (6) Jan 18, 2019
Star formation is one of the least comprehended phenomenon in astrophysics. Is there a general theory of star formation? No, there is not. There is a number of models based on computer simulations which include supersonic hydrodynamics with non-ideal MHD turbulence influenced by gravity. They include the line and continuum radiative processes of the energy transfer; a number of chemical processes with dissociation, recombination and ionization, with uncertain nomenclature of atoms and molecules, unknown magnetic fields and formation and destruction of dust particles. In addition there is macrophysics that is an environment in the molecular clouds, clumps and cores; inclusion in the multiple systems, collisions among stellar systems; jets and outflows; radiation pressure.
https://www.acade...ormation
StudentofSpiritualTeaching
1.4 / 5 (9) Jan 19, 2019
Would things be easier to explain, when realizing that our universe is already 46 trillion years old, rather than the currently falsely assumed 13-14 billion? See paragraph 616 over here: http://www.future...port_230
Da Schneib
3.8 / 5 (10) Jan 19, 2019
Maybe if you were to explain where the CMB came from.
rrwillsj
3.4 / 5 (5) Jan 19, 2019
46 trillion years?

& the deities still screw it up?

Hooray! Another point for my Theory of Stupid Design...

Coyote Trickster Goddess?
You go girl!
StudentofSpiritualTeaching
2.3 / 5 (3) Jan 19, 2019
No, humankind on our planet is not screwed up by pseudo gods and goddesses. This is rather done by arrogance and ignorance, just as described in the linked text.
StudentofSpiritualTeaching
1 / 5 (2) Jan 19, 2019
Da Schreib, why are you asking? The Big Bang theory is correct.
torbjorn_b_g_larsson
5 / 5 (8) Jan 19, 2019
Would things be easier to explain, when realizing that our universe is already 46 trillion years old, rather than the currently falsely assumed 13-14 billion? See ...


The Big Bang theory is correct.


Naturally I don't need to check links to that first false claim, especially on a non-peer reviewed site, what is claimed without evidence can be dismissed without evidence. And I note that you are inconsistent, the known date of the universe follows from big bang theory of old and current inflationary cosmology as well.

The current accepted age is 14 (not 13) billion years with a precision of 0.1 % or so, see the Planck Legacy Archive which aggregates *all* data and has undergone peer review. If that age estimate changes, I am sure the whole world will know about it.
rrwillsj
1 / 5 (1) Jan 19, 2019
"... If that age estimate changes, I am sure the whole world will know about it. ..."

Cause anybody who can publicly out-math Planck? Is damn well going to brag about it! Loudly!!
JaxPavan
3.2 / 5 (9) Jan 20, 2019
I don't know how old the universe is, but I do know how media propaganda works and how politically driven pseudo-science is created.

Used to be the reporters wrote "scientists believe" or "best estimate" when introducing the age of the universe as a preface to some BBT related science or patch. Nowadays reporters state both BBT and the current age estimation as definitive facts. That's sort of a big giveaway that, true or false, they wouldn't report on it as anything but true. At that point it ceases being real science and becomes politically driven pseudo-science, along with a colluding-class echo-chamber of media, publications, grant funding sources (and trolls) it creates careers for true believers to dominate that aspect of the field in research universities, who then add their own self-congratulations to the echo chamber. The pseudo-science then becomes a self licking ice cream cone:
rrwillsj
3 / 5 (4) Jan 20, 2019
Let me guess Jax,
"They" refuse to publish your screeds in any legitimate Scientific journal.
Cause you refuse to allow them to alter a single incoherent rant that you claim as the Sacred Manifested Truth of the Universe!

To add insult to the injury of them so rudely dismissing you? They laughed v& jeered at you as you flounced away in indignation.

Well boy, there is a very simple revenge for you to inflict on all of us hooting & mocking your genius.

Yes there is!

Based upon your glorious vision of perfect mumbo-jumbo, just build a working device.

Anything that would only work in your definition of reality
& not in the reality the rest of us are using for technology.

& heckfire, the ultimate device should be able to eradicate a city. Easy-peasy for a smart tyke like you!

I promise, pinky-swear, to stop laughing at your pretensions to greatness, the very day you succeed in getting anything working.

& no, a badly photoshoped youtuber video won't count.
arcmetal
3 / 5 (8) Jan 20, 2019
@JaxPavan
I don't know how old the universe is, but I do know how media propaganda works and how politically driven pseudo-science is created.

Used to be the reporters wrote "scientists believe" or "best estimate" when introducing the age of the universe as a preface to some BBT related science or patch. Nowadays reporters state both BBT and the current age estimation as definitive facts. That's sort of a big giveaway that, true or false, they wouldn't report on it as anything but true. At that point it ceases being real science and becomes politically driven pseudo-science,...

I've noticed this to be the status quo since the time of Hubble. Back then, Hubble used to label the cosmic red-shift as "apparent velocities". I suppose today its just "velocities". At some point science may regain its sanity, but not today.
JaxPavan
2.3 / 5 (6) Jan 20, 2019
I'm pointing out areas that have become politically driven pseudo-science, They are not necessarily false.

Nuclear winter (false) (well intentioned attempt to make WWIII unthinkable but ultimately much less dust than the St. Helens eruption)

Nuclear EMP (false) (well intentioned idiot bait to get a rogue actor to waste an ill gotten nuke in the upper atmosphere, but the only real evidence is a few blown street lights on Oahu during one atmospheric test of an H-bomb bigger than what we put on warheads.)

AGW (probably false?) (attempt to mitigate the effects of peak oil while removing who looses out from any meaningful informed public debate or democratic process)

BBT (true or false?) (a creation story that supports all three abrahamic religions as well as Luciferian dualists)

Fusion power, flying cars, 3-D printed steel (true or false?) (propaganda to keep the masses mollified and receptive to whatever really comes along such as computers, pharmaceuticals, etc.)
JaxPavan
2.3 / 5 (6) Jan 20, 2019
Other forms of politically driven pseudo-science are more mundane but just as obvious: tobacco "safety" research that lasted decades, modern glyphosate safety research, nuclear safety limits getting tweaked around by the EPA and FDA right after Fukushima, etc.
JaxPavan
2 / 5 (4) Jan 20, 2019
Back to star formation, since there are hundreds of billions of stars in the Milky Way galaxy, and if it is "only" 14 billion years old, then (never-mind all the generations of stars that have already come and gone) we should be seeing at least ten new stars every year. Not necessarily "birth" at the time fusion begins in the core, but when it flares up to become finally visible for the first time from earth. One might suppose that with all these observatories studying star forming regions in our galaxy, they would be comparing imagery and declaring the "birth" of new stars every year.

To my knowledge that has never been confirmed. They can tell you they see stars in various stages of formation, but can't point to any that they couldn't see last years with the same telescope, while holding up two photos to prove it. That seems rather odd.
arcmetal
4 / 5 (4) Jan 20, 2019
Back to star formation,...

To my knowledge that has never been confirmed. They can tell you they see stars in various stages of formation, but can't point to any that they couldn't see last years with the same telescope, while holding up two photos to prove it. That seems rather odd.

Space is very big. It just means we lack the technology to film a specific event, a star being born. To scan the whole region of the visible milkyway at various depths would take a massive telescope device. ... Planes here crash out of the sky all the time, but how many do we have on tape? It is a rare thing. Then again, we now have more videos of crashes, but that is because everyone is holding a video camera. Maybe if everyone had a Hubble telescope in their backyard, we may catch more celestial events.
JaxPavan
3 / 5 (2) Jan 20, 2019
Nevertheless we should be seeing at least a handful of examples of this while staring at star forming regions for decades, given the numbers.
JaxPavan
3 / 5 (2) Jan 20, 2019
It's not like filming a plane crash it's more like counting the number of planes at the airport and noticing a slight increase over time. You can take the pictures whenever and just compare without needing to film or even know when the plane arrived precisely.
arcmetal
3.7 / 5 (3) Jan 21, 2019
Nevertheless we should be seeing at least a handful of examples of this while staring at star forming regions for decades, given the numbers.

I wouldn't really expect that. Consider the life time of a human versus the life time of a star. ... There may be new stars forming in that stellar nursery all the time, but the intervals are probably measured in millions of years, whereas the life of a star is in billions of years.

It would require incredible luck to see that happen, or the luck may get better if we had a way of detecting when a region of space was going to produce a star.
JaxPavan
2.3 / 5 (3) Jan 21, 2019
I respectfully disagree. Hundreds of billions of stars shining in our galaxy times however many previous generations, and only 14 billion years to form. That's at least ten a year, probably a heck of a lot more, on average. You don't need luck, you just need an old picture to compare with a new one. Nevermind when exactly it happened. One would expect that a photo of a star forming region taken today, when compared to one taken, say, decades ago, would have at least several new additions. That doesn't seem to be the case however, despite observatories dedicated to studying star forming regions. (Perhaps I am misapprehending the fields of view?)
Tuxford
1.8 / 5 (5) Jan 21, 2019
except that for some reason smaller galaxies – those with fewer than about ten billion stars – seem to make slighter fewer stars than expected for their masses (the Milky Way is right at the turnover, with about ten billion stars and a rate of roughly one new star per year). A particularly significant consequence of this paucity, if real, is that simulations of galaxy growth do not show it, implying that the simulations are incorrect for smaller galaxies and that some physics is missing.

Indeed, the physics is wrong. Again, in LaViolette's SQK, as the dark supermassive core star grows even more massive, it becomes even more active, exposing new matter (and energy) from the subquantum realm into our detectable realm, and ejecting it periodically to form new stars therefrom. So smaller galaxies with smaller core stars are less active, producing fewer stars than the larger galaxies. It's simply really, except for the confounded merger maniac.
Tuxford
1.8 / 5 (5) Jan 21, 2019
I don't know how old the universe is, but I do know how media propaganda works and how politically driven pseudo-science is created... The pseudo-science then becomes a self licking ice cream cone:

Remember that this site is a DoD/NSA propaganda site, supporting the Huge Bang Fantasy and math-fairy relativists physics, to contain otherwise dangerous electro-gravitic physics from mainstream examination. The spooks must contain the naive physical scientist from wandering too far afield with self-education and asking uncomfortable questions. It is dangerous for too many free thinkers to be wandering the academic institutions. So funding support helps steer the examination away from classified areas. And mockery contains the rest. The UFO counterintelligence effort is an extreme, but easy, example. So you actually think you are free to think? Think again.
rrwillsj
3.7 / 5 (3) Jan 21, 2019
Oh, puh-leeze! If you don't even know the work done by all the different variations of acronym government? You are talking out your ass.

To repeat. The actual purpose pf this phys.org site has two major functions. Three if you are willing to consider selling advertising. But I suspect I am the only commentator who does?

The first & most important is to provide a forum for all the wooloons.

A Public Service to keep them away from pestering the real scientist's communication networks. That they are not inundated with all the blathering nonsense from us wild & wacky non-scientists.

The second purpose to be a collection point for all us crazies. To be observed & monitored by grad students in the Psych Health & Social Sciences fields.

It is our contribution to the sciences of the human mind & modern society. We supply a treasure trove of thesis material.

Pity the cranks can never comprehend how much they have donated their crazy to benefiting Humanity.
JaxPavan
3.7 / 5 (3) Jan 21, 2019
@rrwillsj

Your level of unsolicited trolling, name calling, and fighting words rises to the level of disorderly conduct by electronic media.

What's worse you usually misinterpret what others have written and then launch inapposite criticisms.

As far as keeping questions from scientists, most scientists I have contacted via email regarding questions raised by their books or papers have all given me prompt and cheery replies. Most of them are pleased to have questions from laymen or others outside their field. It adds a broader sense of significance to their work, I suppose. The sole exception was Hawking; never heard back; way too much of a celebrity I guess.
arcmetal
5 / 5 (3) Jan 21, 2019
@rrwillsj

As far as keeping questions from scientists, most scientists I have contacted via email regarding questions raised by their books or papers have all given me prompt and cheery replies. Most of them are pleased to have questions from laymen or others outside their field. It adds a broader sense of significance to their work, I suppose. The sole exception was Hawking; never heard back; way too much of a celebrity I guess.


I found what you say to be very much true. As I wandered the halls of the labs I worked at, there were many that were more than happy to discuss their work, and for us to teach each other new concepts, and ideas. There is no way for any one person to know everything, so friendly conversations about these topics were enjoyed by all. Books and articles are great, but they can't answer direct questions.
Anonym262722
5 / 5 (1) Jan 21, 2019
The problem is revealed by the first sentence: 'The universe is about 13.8 billion years old'. It is based on the assumption that the speed of light C has been constant since BB such that the travel distance R4 =13.8 B l.y. of Riemann 4-sphere (starting point of GR) is covered using the arbitrary definition of today's second and C or by number of ticks/s of physical (vs. absolute) atomic clocks. The ticking rate (and other atomic processes such as decay rate) of physical atomic clocks slows down in local energy frames at the same rate as the TRUE value of decelerating C - due to balancing the motion and gravitational energies of total mass M in 3-d space (closed surface of Riemann 4-sphere). This causes the APPARENT or locally observable C to be constant - fooling GR/QM theories. To see the optimal energy levels and C=C4 values of star formation at R4/2=6.9B l.y or at T4=9.2/2 B yrs, see my past posts and sign up to Dr.Suntola's Feb/March seminars about unified DU via www.lfs.org
FredJose
2 / 5 (4) Jan 22, 2019
"Star formation" is that enigmatic event or process that no one has ever observed or recorded as happening. There is a very simple physical reason for it.
Given the model presented in this article for star formation, I need to point out that in the process of compression by gravity a certain limit is reached beyond which it is not possible to overcome the resulting internally generated heat pressure. This is called the Jeans Mass Limit.
This is a well known and very basic piece of knowledge. There are other problems as well.
So far no one has been able to come up with a way to overcome that pesky little problem using just known physics. So the big bang priests have to introduce dark matter into the equation, never mind that dark matter is as yet unknown and un-characterized. The priests merrily go ahead and assign dark matter the required properties to make star formation work. This is pseudo science beyond belief.
"Star formation" is thrown about as if it is fact. That's a lie.
FredJose
1 / 5 (3) Jan 22, 2019
It is interesting how quick big-bangers are to dismiss creationists but then when the facts get pointed out to them they refuse to accept it and instead attack the creationists.
Let's take planetary self-formation for instance. Right here, in our own solar system, every planet has prominent characteristics that outrightly falsifies any of the versions of planet-self-formation models put forth to date. Mercury is my favourite with scientists admitting they have to rethink their model after the Messenger Reports came out. Venus spinning the "wrong" way, Uranus rolling along merrily, The sun's equatorial plane 5.6 degrees from the invariable, Jupiter and Saturn would take too long to "form", Pluto and its moons calling the lie on supposed billions of years by still being fully active; ditto Enceladus and the moon; Titan's deep seas of ethane not there while still having methane, Saturn's rings are only 10 million years old and have absolutely no known naturalistic cause.I can go on & on.
Da Schneib
4 / 5 (4) Jan 22, 2019
@FreddyJoe confuses planetary and star formation with the Big Bang and then claims nobody knows anything about it.

And then lies about Jeans' Limit.

Do you really want to discuss Jeans' Limit, @FreddyJoe? Because I don't think you know how it works.
Da Schneib
4 / 5 (4) Jan 22, 2019
Here's what Wikipedia says Jeans' Mass Limit is:
If a pocket of gas is massive enough that the gas pressure is insufficient to support it, the cloud will undergo gravitational collapse. The mass above which a cloud will undergo such collapse is called the Jeans mass. This mass depends on the temperature and density of the cloud, but is typically thousands to tens of thousands of solar masses.
https://en.wikipedia.org/wiki/Gravitational_collapse

Doesn't sound much like what you said. It doesn't appear to limit star formation; it merely says that a molecular cloud must be large enough, or cool enough, for gravity to overcome the internal gas pressure of the cloud, in order to form stars.

You're lying, @FreddyJoe, and you're busted.

And it still doesn't have anything to do with the Big Bang.
Anonym262722
5 / 5 (1) Jan 28, 2019
'T4=9.2/2 B yrs, see my past posts and sign up to Dr.Suntola's Feb/March seminars about unified DU via www.lfs.org'. Sorry, the correct name of this site is lfs.fi (science philosophy society of Finland). It has posted also some open literature about DU with layman interpretations in English and Finnish.

Note that the cosmic time T4 at R4= 13.8/2 =6.9 B ly equals T4=9.2/2= 4.6 B (absolute) yrs where the present value of T4 is 9.2 B cosmic yrs when measured by the lengthened second of today (due to the slowing ticking rate of atomic processes of zero energy balancing in present decelerated expansion of R4).

Anonym262722
5 / 5 (1) Jan 28, 2019
How come nobody figured out that cosmic time T4 of decelerated expansion C4 at R4_past =1/2 R4_today is found by computing C4_past=sqrt(2) C4_today and then T4_past= T4_today/sqrt(2)^3=3.25 yrs? Not 4.6 B yrs, sorry for my mistake.
Anonym262722
not rated yet Jan 28, 2019
Thank you PO for rating my corrected comment about the tricky DU cosmic time concept. According to GRT, the value of T4_past at R4_past=13.8/2=6.9 Bly would be 6.9 B yrs or by orders of magnitude in error although the total tick count since BB would be the same as in DU. According to DU energy balancing, the ticking rate of atomic clocks was more than 10 times faster during the bounce until the CMB epoch. GR assumes that the total number of atomic ticks since BB is multiplied by today's maximum long second to get the accumulated absolute age of universe after BB. GRT agrees with DU distance and time concepts in local energy frames when R4_past and absolute T4_past are close to their today's values of 13.8 B ly and 9.2 B yrs but fails in modeling of cosmic observables such as SN1a.
Anonym262722
not rated yet Jan 29, 2019
This DU example of cosmic time T4 and R4 distance as a function of C= C4 complements examples about the experimental Hubble constant determination of Gaia and HST project in late 8/2018 discussion of PO, see https://phys.org/...mic.html
where the change of R4 was only one Mpc or about 3 Mly vs. 6,900 Mly. DU model connecting C4 to R4 and T4 is nonlinear and could be approximated by the interpolation model using two R4 epochs for 1 Mpc. The half-way case of R4 already showed the huge GR timing error (6.9 - 3.25 = 3.65 B yrs) for the 'half-age'' estimates. Nonlinearity of DU physical model shows in the age and distance changes to present values (9.2-3.25 = 5.95 B yrs and 13.8 - 6.9 = 6.9 B ly) within R4 change of 6.9 B ly vs the Hubble constant dR4 difference of 1 Mpc. The main star formation started before T4= 3.25 B yrs but became more visible when the 4-D energy momentum spread from R4 direction toward 3-D space direction due to decelerating C4.
Anonym262722
not rated yet Feb 07, 2019
'T4_past= T4_today/sqrt(2)^3=3.25 yrs? Not 4.6 B yrs, sorry for my mistake'. Of course, it should be 3.25 B yrs not 3.25 yrs. I noticed similar print mistakes in some of my posts of the Hubble constant (71 km/s per Mpc vs. parsec). A careful reader of my posts may wonder why in my early posts I interpreted the frequency and wave length of emitted EM light near CMB release to be 1000 and/or 10 times today's values of received vs. emitted power of SN1a and other cosmic (such as GW or unstructured DM waveform) data. The explanation is complex and confusing using the GR based concepts of distorted time, distance, simultaneity, relativity, equivalence principle, GPS, Planck constant etc. You may find helpful explanations in past presentations and papers by Suntola, Talvio, Sipila, Lehto, Mantyla etc posted by www.lfs.fi and by the books and published papers at www.physicsfoundations.org

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.