SAO: Weekly Science Updates 2017

Find out the latest thinking about our universe.
User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

The Shapes of Galaxies

Postby bystander » Sat Jun 24, 2017 1:58 pm

The Shapes of Galaxies
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jun 23

Since Edwin Hubble proposed his galaxy classification scheme in 1926, numerous studies have investigated the physical mechanisms responsible for the shapes of spiral and elliptical galaxies. Because the processes are complex, however, studies frequently rely on computer simulations as their main tool. The discs of galaxies are believed to form through the collapse of gas which acquires its initial spin in the early Universe. During their subsequent evolution, galaxies undergo a wide range of phenomena, from the accretion of matter -- or its outflow -- to mergers with other galaxies, all of which modify the disk’s spin and angular momentum.

Astronomers think that spiral galaxies with the largest galactic discs formed preferentially in protogalaxies with the highest angular momentum, although early attempts to verify this prediction using computer simulations failed. (More recently, simulations have been able to verify this trend.) Elliptical galaxies, on the other hand, are believed to be the remnants of repeated galaxy mergers, but their shapes depend on many details like the galaxies' masses, gas content, and the collision parameters. As a result, these mergers need to be considered over a cumulative, cosmological context with large numbers of examples to evaluate their development from a statistical perspective.

CfA astronomers Vicente Rodriguez-Gomez, Annalisa Pillepich and Lars Hernquist led a team that analyzed the morphologies of about eighteen thousand galaxies in the Illustris computer simulation. Both disc and spheroidal galaxies arise naturally in this simulation. They find that massive merging galaxies develop into spirals or spheroidal shapes depending on their gas content (as expected, since the star formation activity depends crucially on the gas). Unexpectedly, they find that for lower mass galaxies -- roughly the mass of the Milky Way or smaller -- mergers do not seem to play a significant role in determining the morphology. The reason appears to be that in higher mass mergers a galaxy accretes many more stars from the partner, and this plays the a critical role. Their significant conclusion is that only in massive galaxies are mergers the dominant factor in shaping the system.

The Role of Mergers and Halo Spin in Shaping Galaxy Morphology - Vicente Rodriguez-Gomez et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

The Puzzling Detection of X-Rays from Pluto

Postby bystander » Fri Jun 30, 2017 4:43 pm

The Puzzling Detection of X-Rays from Pluto
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jun 30

Fig.1-EMLisse-etal-Icarus-May2017..png

Pluto is the largest known body belonging to the Kuiper Belt, an orbiting disk of small objects that extends roughly from the orbit of Neptune to fifty AU from the Sun (one AU is the average distance of the Earth from the Sun). Pluto is known to have an atmosphere which changes size and density with its seasons, and preliminary results from the New Horizons flyby revealed that the atmosphere is primarily composed of nitrogen. Pluto, like all solar system objects, is immersed in the interplanetary solar wind, and the way it interacts with the wind depends on the properties of its atmosphere. Most models of Pluto’s atmosphere before the flyby expected it to be quite extended. When the solar wind interacts with neutral gas like nitrogen it is expected to induce X-ray emission; such emission is seen from other solar system bodies, like comets, Venus and Mars. Astronomers therefore decided to look for analogous emission from Pluto’s atmosphere using the Chandra X-ray Observatory.

CfA astronomer Scott Wolk was a member of a team that undertook the Chandra measurements. From its close flyby, New Horizons found that Pluto's atmosphere was not as extended as had been expected with an escape rate of the gas into space that is hundreds of times smaller than expected. But, to the surprise of the team, the X-ray emission was strong anyway, noticeably stronger than would have been expected for the smaller atmosphere. X-rays from other solar system objects arise from strong aurorae, for example, or the scattering of solar x-rays from small dust grains composed of carbon, nitrogen, and oxygen. Pluto's X-rays, although relatively strong, are unlike these in their energy distribution. The cause of the X-ray emission remains mysterious, but the astronomers speculate that it could be due to some process(es) that focus the solar wind near Pluto to enhance the effect of its modest atmosphere.

The Puzzling Detection of X-rays from Pluto by Chandra - C. M. Lisse et al

viewtopic.php?p=262250#p262250
viewtopic.php?t=36388
You do not have the required permissions to view the files attached to this post.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Y-Type Stars

Postby bystander » Mon Jul 10, 2017 6:12 pm

Y-Type Stars
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jul 07

Brown dwarf stars are failed stars. Their masses are so small, less than about eighty Jupiter-masses, that they lack the ability to heat up their interiors to the roughly ten million kelvin temperatures required for normal hydrogen burning (hydrogen burning fuels the Sun, whose surface temperature is about 5700 kelvin). The surface temperatures and properties of brown dwarfs depend on their precise masses and ages, and range from a few thousand degrees down to a mere 200 kelvin (comparable to the Earth’s surface temperature) with the warmest group being designated as L Dwarfs, the next warmest group as T Dwarfs, and the coolest objects as Y Dwarfs. Not surprisingly, because they are so cool, brown dwarfs are faint and hard to detect, and so although theorists predict that there could be as many brown dwarf stars as there are normal stars our understanding of their evolution and interior properties is quite incomplete.

NASA's Wide-field Infrared Survey Explorer (WISE), which was sensitive to the emission from cool objects, discovered the Y class of brown dwarfs in 2011, and today there are twenty-four of them known. CfA astronomer Caroline Morley and her colleagues used the Spitzer Space Telescope and the Gemini observatory, as well as some other facilities, to refine the distances, luminosities, colors, and spectral characteristics of these objects and compared the results to current models. The scientists determined the masses and ages for twenty-two of them, and confirmed that, at least for the slightly warmer Y-dwarfs (whose temperatures are around 450 kelvin) the cloud-free surface models agree with observations. All of them have elemental abundances comparable to those found in the Sun, and all appear to have turbulent atmospheres. However for the coolest few objects, whose temperatures are more like 250 kelvin, the models do not agree. A larger sample of objects for study would help to constrain the parameters, but the authors note that it is unlikely more will be found until a more sensitive infrared mission is flown.

The Y-type Brown Dwarfs: Estimates of Mass and Age from New Astrometry,
Homogenized Photometry, and Near-infrared Spectroscopy
- S. K. Leggett et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

BDanielMayfield
Don't bring me down
Posts: 1348
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: South Texas

Re: Y-Type Stars

Postby BDanielMayfield » Mon Jul 10, 2017 6:30 pm

Y, as in whY call it a star? Many of these now colder than room temperature Brown Dwarfs may have never been able to ignite fusion at all.

Bruce
"Happy are the peaceable ... "

User avatar
Ann
4725 Å
Posts: 8308
Joined: Sat May 29, 2010 5:33 am

Re: Y-Type Stars

Postby Ann » Mon Jul 10, 2017 7:44 pm

BDanielMayfield wrote:Y, as in whY call it a star? Many of these now colder than room temperature Brown Dwarfs may have never been able to ignite fusion at all.

Bruce


Click to play embedded YouTube video.
Good question, Bruce. I think - and make that think - that these little Y thingies are called stars because they form like stars. That is, they form at the center of a cool rotating dusty gas cloud, not from the accretion disk surrounding the young star that has already formed.

So they form like this, apart from the fusion part of the process: :arrow:

They don't form like this!

Or so I think anyway!

Ann
Color Commentator

BDanielMayfield
Don't bring me down
Posts: 1348
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: South Texas

Re: Y-Type Stars

Postby BDanielMayfield » Mon Jul 10, 2017 8:15 pm

But since all stars are thought to form in pairs that formation distinction may not really exist, since most stars would have formed as part of an orbiting clump of cloud too.

The common definition of 'star' is broad, simply meaning point of light in the sky, without regard to what powers the illumination. The heat and light is first produced by gravitational compression. That would be common to all "stars", even the ones that fail to ignite any fusion at the core.

Bruce
"Happy are the peaceable ... "

User avatar
neufer
Vacationer at Tralfamadore
Posts: 14087
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: Y-Type Stars

Postby neufer » Mon Jul 10, 2017 10:26 pm

BDanielMayfield wrote:
Y, as in whY call it a star?

Many of these now colder than room temperature Brown Dwarfs may have never been able to ignite fusion at all.

Brown Dwarfs are all assumed to fuse deuterium (2H) and/or lithium (7Li).

(We certainly think that we understand that much better than how anything was once formed.)

If it fuses it is a star; if it doesn't fuse it (probably) isn't; Y R U confused :?:
Art Neuendorffer

BDanielMayfield
Don't bring me down
Posts: 1348
Joined: Thu Aug 02, 2012 11:24 am
AKA: Bruce
Location: South Texas

Re: Y-Type Stars

Postby BDanielMayfield » Tue Jul 11, 2017 2:57 am

neufer wrote:
BDanielMayfield wrote:
Y, as in whY call it a star?

Many of these now colder than room temperature Brown Dwarfs may have never been able to ignite fusion at all.

Brown Dwarfs are all assumed to fuse deuterium (2H) and/or lithium (7Li).

(We certainly think that we understand that much better than how anything was once formed.)

If it fuses it is a star; if it doesn't fuse it (probably) isn't; Y R U confused :?:


There are things I never knew (vast set), things I think I know (some of which are true, some just possible, and some false), and some things I used to know but have forgotten. Plenty of room for confusion.

Yeah, I should have remembered that by definition all BDs begin fusion but cannot fuse H via the proton-proton chain. Doh!

Bruce
"Happy are the peaceable ... "

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

The Formation of Giant Planets

Postby bystander » Fri Jul 21, 2017 3:39 pm

The Formation of Giant Planets
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jul 14

The planets in our Solar System formed in orbits that depended on the initial distribution of the matter in solar nebula. In particular, the most popular theory for the formation of giant gas planets argues that their rock-and-ice cores formed gradually through coagulation of smaller planetesimals until they were massive enough to accrete gaseous envelopes. The spatial distribution of gas in a primitive nebula is therefore critical not only to the accretion of the atmosphere of its giant planets but also to the formation of these early planetesimals. Many young stars are ringed by disks of dust from which new planets will form. Since that dust emits in the infrared, astronomers have been studying the rings in the infrared to constrain the models of solar system evolution. Only about one percent of the matter is in the form of dust however; the bulk is in gas, which is much harder to detect. Astronomers have tried, but so far have primarily only been able to detect the surface layer of the gas lying above the bulk mass reservoir.

CfA astronomer Ilse Cleeves and her colleagues used the ALMA facility to obtain the first spatially resolved observations of gas emission in a protoplanetary disk, the closest one to us around the star TW Hydrae. They observed it in a relatively rare isotopic species of CO that enabled them to probe the full thickness of the disk. By combining their results with other datasets, they were able to constrain the temperature, gas and dust abundances throughout the disk. They were also able to measure how these quantities vary with distance from the star, in particular in the key zone from about five to twenty astronomical units where giant planets are expected to form (one AU is the average distance of the Earth from the Sun). ...

Mass Inventory of the Giant-Planet Formation Zone in a Solar Nebula Analogue - Ke Zhang et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Mapping Dark Matter

Postby bystander » Fri Jul 21, 2017 4:00 pm

Mapping Dark Matter
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jul 21

About eighty-five percent of the matter in the universe is in the form of dark matter, whose nature remains a mystery. The rest of the matter in the universe is of the kind found in atoms. Astronomers studying the evolution of galaxies in the universe find that dark matter exhibits gravity and, because it is so abundant, it dominates the formation of large-scale structures in the universe like clusters of galaxies. Dark matter is hard to observe directly, needless to say, and it shows no evidence of interacting with itself or other matter other than via gravity, but fortunately it can be traced by modeling sensitive observations of the distributions of galaxies across a range of scales.

Galaxies generally reside at the centers of vast clumps of dark matter called haloes because they surround the clusters of galaxies. Gravitational lensing of more distant galaxies by dark matter haloes offers a particularly unique and powerful probe of the detailed distribution of dark matter. So-called strong gravitational lensing creates highly distorted, magnified and occasionally multiple images of a single source; so-called weak lensing results in modestly yet systematically deformed shapes of background galaxies that can also provide robust constraints on the distribution of dark matter within the clusters.

CfA astronomers Annalisa Pillepich and Lars Hernquist and their colleagues compared gravitationally distorted Hubble images of the galaxy cluster Abell 2744 and two other clusters with the results of computer simulations of dark matter haloes. They found, in agreement with key predictions in the conventional dark matter picture, that the detailed galaxy substructures depend on the dark matter halo distribution, and that the total mass and the light trace each other. They also found a few discrepancies: the radial distribution of the dark matter is different from that predicted by the simulations, and the effects of tidal stripping and friction in galaxies are smaller than expected, but they suggest these issues might be resolved with more precise simulations. Overall, however, the standard model of dark matter does an excellent and reassuring job of describing galaxy clustering.

Mapping substructure in the HST Frontier Fields cluster lenses and in cosmological simulations - Priyamvada Natarajan et al

viewtopic.php?t=36910
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

The Outer Galaxy

Postby bystander » Sat Jul 29, 2017 4:16 pm

The Outer Galaxy
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Jul 28

The Sun is located inside one of the spiral arms of the Milky Way galaxy, roughly two-thirds of the way from the galactic center to the outer regions. Because we are inside the galaxy, obscuration by dust and the confusion of sources along our lines-of-sight make mapping the galaxy a difficult task. Astronomers think that the galaxy is a symmetric spiral, and about ten years ago CfA astronomers Tom Dame and Pat Thaddeus using millimeter observations of the gas carbon monoxide discovered symmetric components to the spiral arms deep in the inner galaxy that lent support to this model.

The galaxy is not perfectly flat. It has a slight warp that allows some distant structures, at least in the direction of the constellations of Scutum and Centaurus, to be seen more distinctly above much of the foreground confusion. In 2011 the same CfA astronomers were the first to discover a large-scale spiral feature within this distant warp which they called the “Outer Scutum–Centaurus Arm (OSC).” Subsequent studies placed the OSC at a distance from the galactic center of over forty thousand light-years; it appears to be a symmetric counterpart to a spiral arm on the opposite side, in the direction of Perseus. ...

High-Mass Star Formation in the Outer Scutum-Centaurus Arm - W. P. Armentrout et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
Ann
4725 Å
Posts: 8308
Joined: Sat May 29, 2010 5:33 am

Re: The Outer Galaxy

Postby Ann » Sat Jul 29, 2017 6:55 pm

Smithsonian Astrophysical Observatory wrote:

CfA astronomer Tom Dame has joined with a set of collaborators to probe the extent of massive star formation in the OSC (Outer Scutum-Centaurus Arm); sadly, his colleague Pat Thaddeus passed away earlier this year.

Using radio measurements of ionized gas, which traces the hot ultraviolet from massive young stars, as well as bright emission from masers associated with massive star formation, the scientists observed 140 candidate locations and discovered evidence for massive young stars in about sixty percent of them.


Sorry for growing unnecessarily poetic, but I find this really moving. An astronomer, Pat Thaddeus, is diligently searching an awkwardly placed part of the sky for signs of star formation in a previously undiscovered outer spiral arm of our galaxy, and he finds enough evidence to make it very likely that this outer arm exists. Bur before Pat Thaddeus could see the his work come to an end, he died.

This is how astronomy is being done by humans. Individual tiny, terribly brief carbon-based life forms search the incredibly huge universe to tease out evidence of what this amazing vastness is, and what components it contains.

The tiny little carbon-based life forms work hard and make large and small discoveries. Some time afterwards, the little life forms grow feeble and die in less than a cosmic blink of an eye. Other, equally brief life forms preserve their deceased colleagues' work and keep on adding to it, themselves ceasing to be soon afterwards but handing over their knowledge to yet another generation of astronomers. Thus the scientists of humanity use their brief little lives to build an ever more complete (but never truly complete) picture of the universe.

Seen this way, humanity's curiosity and courage is quite moving.

Click to play embedded YouTube video.

Ann
Color Commentator

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Magnetic Fields in Massive, Star Formation Cores

Postby bystander » Wed Aug 09, 2017 7:53 pm

Magnetic Fields in Massive, Star Formation Cores
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Aug 04

Studies of molecular clouds have revealed that star formation usually occurs in a two step process. First, supersonic flows compress the clouds into dense filaments light-years long, after which gravity collapses the densest material in the filament into cores. In this scenario, massive cores (each more than about twenty solar–masses) preferentially form at intersections where filaments cross, producing sites of clustered star formation. The process sounds reasonable and is expected to be efficient, but the observed rate of star formation in dense gas is only a few percent of the rate expected if the material really were freely collapsing. To solve the problem, astronomers have proposed that magnetic fields support the cores against the collapse induced by self-gravity.

Magnetic fields are difficult to measure and difficult to interpret. CfA astronomers Tao-Chung Ching, Qizhou Zhang, and Josep Girat led a team that used the Submillimeter Array to study six dense cores in a nearby star formation region in Cygnus. They measured the field strengths from the polarization of the millimeter radiation; elongated dust grains are known to be aligned by magnetic fields and to scatter light with a preferred polarization direction. The scientists then correlated the field direction in these cores with the field direction along the filament out of which the cores developed.

The astronomers find that the magnetic field along the filament is well-ordered and parallel to the structure, but at the cores themselves the field direction is much more complex, sometimes parallel and sometimes perpendicular. They conclude that during the formation of the cores the magnetic fields, at least at small scales, become unimportant compared to turbulence and infall. Although the field may play an important role as the filament initially collapses, once the dense cores develop the local kinematics from infall and gravitational effects become more important.

Magnetic Fields in the Massive Dense Cores of the DR21 Filament:
Weakly Magnetized Cores in a Strongly Magnetized Filament
- Tao-Chung Ching et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Properties of a Massive Galaxy 800 Million Years after the Big Bang

Postby bystander » Fri Aug 11, 2017 4:51 pm

Properties of a Massive Galaxy 800 Million Years after the Big Bang
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Aug 11

Searches for the most distant galaxies have now probed earlier than the first billion years in the history of the universe, early enough to start seeing the primary effects of the first stars: the reionization of neutral atoms. Astronomers want to understand how galaxies formed and evolved in this period, the timescale over which this reionization took place, the nature of the objects that provided the ionizing photons, and the scenarios in which galaxies and their interstellar medium (ISM) become enriched with atoms made in stellar furnaces. Although galaxies from this era are currently being discovered in deep optical and near-infrared surveys, most of them are low-mass galaxies, very faint, and the enrichment process is difficult to study. More luminous, massive star-forming galaxies are thought to be present and to play a major role in reionization, but because these large objects are difficult to assemble so early in cosmic time there are not many of them.

Massive star-forming galaxies that contain dust emit strongly radiation at submillimeter wavelengths and these objects can be find using submillimeter telescopes. They therefore offer the opportunity to study extreme cases of metal/dust enrichment of the ISM early in the era of reionization. CfA astronomers Matt Ashby and Chris Hayward were members of a large team using the South Pole Telescope to detect a set of these dusty galaxies. They determined their distances using the ALMA telescopes by looking at the redshifted wavelength of carbon monoxide molecule in their ISM. The farthest known dusty galaxy was detected in this way, and subsequent observations of it with other facilities confirmed its cosmological distance. The scientists constrained the properties of the object by modeling the observed continuum and spectral lines, and found that the object has a mass in gas of about 330 billion solar-masses; for comparison, the estimated gas mass of the Milky Way is about five billion solar-masses (most of its mass is in stars). The dusty galaxy is forming new stars at an estimated rate of several thousand per year - although with the assumption that the process is similar to what is seen in nearby galaxies. This rare and distant object offers one of the best probes so far into the activity in galaxies when the universe was very young.

ISM Properties of a Massive Dusty Star-Forming Galaxy Discovered at z ~ 7 - M. L. Strandet et al
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
bystander
Apathetic Retiree
Posts: 15964
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: SAO: Weekly Science Updates 2017

Postby bystander » Tue Aug 22, 2017 4:38 pm

The Origin of Binary Stars
Smithsonian Astrophysical Observatory
Weekly Science Update | 2017 Aug 18

53a4cf9444c742510cbaa3c550ef4f74[1].jpg

The origin of binary stars has long been one of the central problems of astronomy. One of the main questions is how stellar mass affects the tendency to be multiple. There have been numerous studies of young stars in molecular clouds to look for variations in binary frequency with stellar mass, but so many other effects can influence the result that the results have been inconclusive. These complicating factors include dynamical interactions between stars that can eject one member of a multiple system, or on the other hand might capture a passing star under the right circumstances. Some studies, for example, found that younger stars are more likely to be found in binary pairs. One issue with much of the previous observational work, however, has been the small sample sizes.

CfA astronomer Sarah Sadavoy and her colleague used combined observations from a large radio wavelength survey of young stars in the Perseus cloud with submillimeter observations of the natal dense core material around these stars to identify twenty-four multiple systems. The scientists then used a submillimeter study to identify and characterize the dust cores in which the stars are buried. They found that most of the embedded binaries are located near the centers of their dust cores, indicative of their still being young enough to have not drifted away. About half of the binaries are in elongated core structures, and they conclude that the initial cores were also elongated structures. After modeling their findings, they argue that the most likely scenarios are the ones predicting that all stars, both single and binaries, form in widely separated binary pair systems, but that most of these break apart either due to ejection or to the core itself breaking apart. A few systems become more tightly bound. Although other studies have suggested this idea as well, this is the first study to do so based on observations of very young, still embedded stars. One of their most significant major conclusions is that each dusty core of material is likely to be the birthplace of two stars, not the single star usually modeled. This means that there are probably twice as many stars being formed per core than is generally believed.

Embedded Binaries and Their Dense Cores - Sarah I Sadavoy, Steven W. Stahler
You do not have the required permissions to view the files attached to this post.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor


Return to “The Communications Center: Breaking Science News”

Who is online

Users browsing this forum: CommonCrawl [Bot] and 0 guests