astrobites 2017

Find out the latest thinking about our universe.
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The oldest dust bunnies in the universe

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

The oldest dust bunnies in the universe
astrobites | 2017 Aug 02
Mia de los Reyes wrote:
Dust isn’t just something to sweep up under your bed. In fact, when we observe a galaxy outside the Milky Way, dust is everywhere, strongly affecting what we see. There’s dust between us and the galaxy (including dust in the Milky Way itself), which absorbs the light from the galaxy. We can correct for this using dust maps, which tell us how much dust is in the direction of the galaxy.

Then there’s dust within the galaxy itself, which is a bit trickier. All of the radiation produced within the galaxy—especially radiation from star formation—is susceptible to absorption by this dust. The dust then re-radiates the absorbed energy in the form of infrared light. Infrared light, therefore, traces both the amount of dust and the amount of star formation in a galaxy. ...

An amplified dusty star-forming galaxy at z=6: unveiling an elusive population of galaxies - Jorge A. Zavala et al
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The Generation Game

Postby bystander » Wed Aug 09, 2017 7:20 pm

The Generation Game
astrobites | 2017 Aug 03
Paddy Alton wrote:
Stars are a sociable bunch, by and large. They don’t like to be alone: some hang out in pairs, or sometimes in small groups of three or four. Others still are extreme extroverts, keeping company with hundreds of thousands of other stars, for example in densely packed globular clusters (GCs) ...

This isn’t be the first article on star clusters to feature on astrobites – and you can be pretty sure it won’t be the last. After all, we’ve been studying them since the seventeenth century and people are still publishing papers about them! ...

Young LMC clusters: the role of red supergiants and multiple stellar
populations in their integrated light and CMDs
- Randa S. Asa'd et al
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The mass of Kepler-10c revisited

Postby bystander » Fri Aug 11, 2017 3:47 pm

The mass of Kepler-10c revisited: upping the radial velocities game
astrobites | 2017 Aug 07
Leonardo dos Santos wrote:
Kepler-10 (or K-10 for the acquainted) is one of those exoplanet-hosting stars that keep on giving us more and more reasons to scratch our heads. A publication from 2014 claimed that K-10c was a weirdly massive planet, possibly of a new kind of extremely solid object. Cue another study two years later — using the same technique, mind you — and a 3-times lower mass was measured. It turns out that the key piece to solve this puzzle is not exactly more data, but a more careful analysis of the already available data. ...

Pinning down the mass of Kepler-10c: the importance of sampling
and model comparison
- Vinesh Rajpaul, Lars A. Buchhave, Suzanne Aigrain
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A (Sub-Millimetre) Galaxy Far, Far Away

Postby bystander » Fri Aug 11, 2017 4:06 pm

A (Sub-Millimetre) Galaxy Far, Far Away
astrobites | 2017 Aug 08
Matthew Green wrote:
Disclaimer: This paper was covered in a previous astrobite by Mia de los Reyes.

Today’s paper is about the discovery of G09 83808, a distant, dusty, and star-forming galaxy that might help us learn more about star formation in the early Universe. ...

An amplified dusty star-forming galaxy at z=6: unveiling an elusive population of galaxies - Jorge A. Zavala et al
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A Treasure Map of Massive Stars

Postby bystander » Fri Aug 11, 2017 4:16 pm

A Treasure Map of Massive Stars
astrobites | 2017 Aug 09
Benny Tsang wrote:
Charting a map of the densest gas clouds in the Milky Way will lead us to the hidden corners of our home galaxy where new stars form. It is not surprising as stars are basically extra-dense clouds of gas that shine with light produced by fusing hydrogen nuclei in their cores. Mapping the locations of the densest clouds is therefore equivalent to finding stars-to-be before their nuclear engines turn on. Creating detailed maps of gas and dust in the Universe is therefore crucial to outlining the environments in which stars and planets form (a vision that kept appearing in the recent 230th AAS meeting). ...

The ATLASGAL survey: The sample of young massive cluster progenitors - T. Csengeri et al

viewtopic.php?t=35673
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Somewhere in the Stratosphere

Postby bystander » Fri Aug 11, 2017 4:22 pm

Somewhere in the Stratosphere
astrobites | 2017 Aug 10
Elisabeth Matthews wrote:
Hot Jupiters are pretty weird. That’s unsurprising, given that they are planets the size of Jupiter, but are closer to their host stars than Mercury is to the Sun. This can produce some pretty wacky environments. Hot Jupiters can reach incredible temperatures (KELT-16b is 2500K), which can lead to extreme weather systems, such as rains made of glass. Meanwhile, some of these hot Jupiters are literally evaporating away, or dissipating onto their host stars. Astronomers are just beginning to learn what these alien worlds are like. A recent paper studied the atmosphere of 10 hot Jupiters, and was covered here on astrobites by Natasha Batalha. This paper marked the beginning of the period of so-called “comparative exoplanetology”. Enough exoplanets have now been observed that we can start to compare their different atmospheres and weather systems, and attempt to find trends and understand their formation and evolution.

Today we focus on one particularly weird hot Jupiter: WASP-121b. This planet is just 0.025AU from its host star, meaning that it orbits the star every 1.28 days. Any visitors to this planet get to celebrate a lot of birthdays! However, they would also have to survive the toasty ~2700K upper atmosphere, so I suggest you think twice before investing in party hats. ...

An ultrahot gas-giant exoplanet with a stratosphere - Thomas M. Evans et al

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Predicting a 21cm AGN reionization signal

Postby bystander » Fri Aug 11, 2017 4:35 pm

Predicting a 21cm AGN reionization signal
astrobites | 2017 Aug 11
Joshua Kerrigan wrote:
It’s a generally accepted idea that the earliest galaxies reionized the universe, however it’s always interesting and fun to explore potentially rare sources, especially when they’re as cool as AGN. Now “what are AGN ?” you may ask. Active Galactic Nuclei, such as quasars, are a galaxy with a compact core that are thought to host supermassive black holes at their center. These central black holes accrete matter surrounding them, causing these galaxies to have an abnormally high luminosity across the electromagnetic spectrum. Initially it was thought that AGN at high redshift were uncommon and therefore could not be a primary source for reionization. Recent detections of high redshift AGN have changed that outlook and this motivates today’s astrobite about how AGN affect the 21cm signal from reionization. ...

Large 21-cm signals from AGN-dominated reionization - Girish Kulkarni et al
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Cosmology Results from The Dark Energy Survey!

Postby bystander » Tue Aug 15, 2017 3:12 pm

Cosmology Results from The Dark Energy Survey!
astrobites | 2017 Aug 14
Gourav Khullar wrote:
I must tell you, these survey results were a long time coming. With CMB telescopes vastly expanding our understanding of the early universe the past two decades, it was only a matter of time before we gained the capability to perform a census of the millions of galaxies at our disposal today using ground based telescopes. This is a very important step: studying today’s galaxies tells us whether the universe evolved after the CMB the way we think it did.

Today’s bite is not just about thanking the early universe for being kind in its evolution, but also an ode to the 400+ scientists working over the last two decades to bring this census to fruition!

The Dark Energy Survey (DES) is a 5-year long endeavor meant to map astrophysical objects over 1/8th of the total night sky visible from Earth (5000 square degrees!), making it one of the largest all-sky surveys ever undertaken from the Earth. DES, which has been in operation since 2013 and is being considered the natural successor to the Sloan Digital Sky Survey (SDSS), uses the 4m Blanco Telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile for its observations.

Attached to the Blanco telescope is the Dark Energy Camera ([url]DECam[/url]), the gift of the DES collaboration to the scientific community. DECam is a 570 megapixel camera (which until a couple years ago was the most powerful digital camera in the world) that captures millions of objects during every night of operation. Its objective? To put constraints on the cosmology of the universe, and to inform formation and evolution models by studying the distribution of galaxies. ...

Dark Energy Survey Year 1 Results:

    Cosmological Constraints from Galaxy Clustering and Weak Lensing - DES Collaboration: T. M. C. Abbott et al
    Photometric Data Set for Cosmology - A. Drlica-Wagner et al
    Redshift Distributions of the Weak Lensing Source Galaxies - B. Hoyle et al
    Weak Lensing Shape Catalogues - J. Zuntz et al
    The Impact of Galaxy Neighbours on Weak Lensing Cosmology with im3shape - S. Samuroff et al
    Curved-Sky Weak Lensing Mass Map - C. Chang et al
    Galaxy Clustering for Combined Probes - J. Elvin-Poole et al
    Galaxy-Galaxy Lensing - J. Prat et al
    Cosmological Constraints from Cosmic Shear - M. A. Troxel et al
    Multi-Probe Methodology and Simulated Likelihood Analyses - E. Krause et al

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New twinkles in the sky

Postby bystander » Tue Aug 15, 2017 3:23 pm

New twinkles in the sky
astrobites | 2017 Aug 15
Ingrid Pelisoli wrote:
Has the Sun ever winked at you? It was probably too subtle for you to notice, but this definitely has happened. Our Sun’s brightness is constantly varying due to convective bubbles near its surface. Other stars similar to the Sun undergo the same process, forming a class of pulsating stars called solar-like oscillators. This is only one of many classes of pulsating stars. We are very lucky that stars pulsate and we are able to detect that: this is the only way we can explore the interior of stars. The frequency of the pulsations we can detect depends directly on the internal structure of the star, so this method allows us to probe stellar interiors and check if what we obtain from our stellar evolution models is correct.

Thus astronomers are constantly sweeping the sky in search of new pulsators. There are dedicated projects doing that, but sometimes data from projects with other scientific goals can be used. One project that has so far revealed the existence of almost 500,000 pulsating stars is the Optical Gravitational Lensing Experiment (OGLE). As the name suggests, the goal of the project is to study dark matter though microlensing phenomena. Matter, be it dark or not, bends the light, focusing it and acting as a magnifying glass. Identifying regions where this magnification occurs is a way to study objects that emit little or even no light. To achieve that, photometric data was obtained for about a billion stars over the years, allowing also the search for pulsators. With such a huge amount of data, there’s a good chance of finding something new and rare. That’s exactly what the authors of today’s paper spotted: an entirely new class of variables, with some properties which are kind of hard to explain.

Blue large-amplitude pulsators as a new class of variable stars - Pawel Pietrukowicz et al
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Re: astrobites 2017

Postby Ann » Wed Aug 16, 2017 5:18 am

BLUE twinkles! :D

(I know... I'm beyond predictable.)

One more thing, though. As expected, these variable and very blue stars have in all probability undergone mass loss. Stars not on the main sequence are blue because they are smaller than their red "cousins", and their surface is closer to their hot interior.

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Links in the Evolution Chain of Post-Starburst Galaxies

Postby bystander » Tue Aug 22, 2017 4:49 pm

Links in the Evolution Chain of Post-Starburst Galaxies
astrobites | 2017 Aug 16
Jamila Pegues wrote:
If you’ve ever spared a quick, casual glance at the night sky, you may have noticed a few bright stars, sparkling bravely alongside the Moon. But if you look long enough and deep enough, you’ll notice that there’s a lot more out there than just a few twinkling stars. Figure 1 shows a beautiful snapshot of the Hubble Ultra Deep Field, where we can see not just stars but galaxies – nearly 10,000 of them! – across an area that’s only about one-tenth the length of the full Moon. The galaxies that we see come in all sorts of shapes, sizes, ages, and colors, but astronomers, like the authors of today’s astrobite, believe that there are similarities and patterns in how each of these galaxies grow and evolve. ...

The Evolutionary Sequence of Post-Starburst Galaxies - C. L. Wilkinson, K. A. Pimbblet, J. P. Stott
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Sneaky pete baryons in gravitational lensing

Postby bystander » Tue Aug 22, 2017 4:57 pm

Sneaky pete baryons in gravitational lensing
astrobites | 2017 Aug 21
Suk Sien Tie wrote:
When a photon perilously escapes being engulfed by gases in its galaxy, it embarks on a long journey to reach our telescopes. Along the way, the combined gravitational field of nearby galaxies and galaxy clusters lures the photon away from sticking to a straight path. Occasionally, its path gets very bent when it passes very close to a galaxy, so much so that when the photon reaches our telescope, we see multiple images of the galaxy where the photon originates. This phenomenon of light bending due to the gravity of matter is known as gravitational lensing. ...

In the context of today’s paper, gravitational lensing is a tool to detect dark matter substructures in the halo of the lensing galaxy. Dark matter is that mysterious stuff that makes up nearly 85% of the Universe mass, does not emit light, and interacts only through gravity. The ratio of fluxes between any pair of lensed images is sensitive to the underlying mass distribution of the lens galaxy. In the absence of dark matter substructures, the flux ratios of the images are well predicted using a smooth lens model. But it does not work as well if dark matter substructures are present, resulting in anomalous flux ratios. Hence, flux ratio anomaly is a telltale sign of dark matter.

Or is it? ...

Flux-ratio anomalies from discs and other baryonic structures in the Illustris simulation - Jen-Wei Hsueh et al
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AlwaysRight

Re: Why I won’t change my mind

Postby AlwaysRight » Wed Aug 23, 2017 8:26 pm

bystander wrote:Why I won’t change my mind
astrobites | 2017 Jan 21
Zephyr Penoyre wrote:
We hope you’re enjoying our beyond posts, going beyond astronomical research and beyond published papers to talk about issues facing astronomers and astronomy in general.

I’m going to go a step further, and talk about an issue that directly affects not only anyone in astronomy, but also anyone who consumes any form of science media. Heck, it concerns anyone who consumes oxygen.

I’m going to talk about a paper that shows us how intractable our opinions can become, and how taking in more information may not actually free us from our biases. ...

Climate-Science Communication and the Measurement Problem - Dan M. Kahan


Because I am, Always Right.

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What’s that coming over the disk?

Postby bystander » Tue Aug 29, 2017 2:16 pm

What’s that coming over the disk?
astrobites | 2017 Aug 24
Amber Hornsby wrote:
Since the discovery of planets around other stars in 1992, our catalogue of exoplanets has grown to an astonishing 3,506 confirmed planets. Thanks to great advances in both space and ground-based observatories, parallels to our own solar system are being uncovered at an ever-increasing rate. Despite this, we are still struggling to find evidence of minor bodies like moons, asteroids, and comets around other stars.

Today’s bite explores the first likely Kepler detection of something that may have played a role in the formation of life here on Earth – an exocomet! ...

Likely Transiting Exocomets Detected by Kepler - S. Rappaport et al
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The Sad Case of GRB 111005A

Postby bystander » Tue Aug 29, 2017 2:23 pm

The Sad Case of GRB 111005A: a Lonely, Nearby Gamma-Ray Burst
astrobites | 2017 Aug 25
Thankful Cromartie wrote:
Gamma-ray bursts (GRBs) are famous for being the brightest astrophysical explosions, boasting apparent energy releases of up to 8.8 × 1054 erg (about five times the sun’s mass in energy). If the burst lasts for fewer than a couple seconds, it is classified as a short GRB — thought to be the result of neutron star mergers. Long GRBs, with durations between a few and hundreds of seconds, are thought to arise when a massive star undergoes core collapse, producing jets from accretion onto the star’s massive remnant (referred to as the collapsar model). One critical piece of evidence supporting this model is the majority of long GRBs being accompanied by supernova (SN) signatures originating from the same location at the same time.

The paper motivating today’s astrobite gives an account of the GRB 111005A, a long-duration burst with no detected SN features. Likely associated with the galaxy ESO 580-49, this burst is the second-closest GRB ever detected (which makes it even more surprising that no SN component could be observed). The authors employed several techniques to scour the environment around 111005A for clues that might explain its apparent loneliness; however, the mystery of our missing SN has yet to be solved. In fact, this work suggests that its absence may signal the necessity of an entirely new class of long GRBs without SN associations. ...

The environment of the SN-less GRB 111005A at z = 0.0133 - M. Tanga et al
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Lightning on Exoplanets

Postby bystander » Tue Aug 29, 2017 2:31 pm

Lightning on Exoplanets
astrobites | 2017 Aug 28
Shang-Min Tsai wrote:
Take a guess at how many lightning strikes are happening at this moment on Earth. The answer is amazingly around 100 every second! That’s billions of flashes per year. You can actually monitor the lightning occurring over the world in real time here. Lightning discharging generates electromagnetic waves over a broad frequency range, including optical flash and radio pulses. Albeit being a transient and local phenomenon, with such a high occurrence rate, lightning alters the chemistry of Earth’s atmosphere, converting N2 to NO and NO2. Besides our Earth, lightning has also been observed on Jupiter and Saturn, identified by the optical flash or the radio signal. In today’s bite, the authors take an even further step. They analyze whether lightning can explain the mysterious radio signals from the exoplanet HAT-P-11b. ...

Is lightning a possible source of the radio emission on HAT-P-11b? - Gabriella Hodosán, Paul B. Rimmer, Christiane Helling
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HAT-P-11: A Spotted Star

Postby bystander » Tue Aug 29, 2017 2:42 pm

HAT-P-11: A Spotted Star
astrobites | 2017 Aug 29
Philipp Plewa wrote:
Although generally known for being a dependable source of light and warmth to life on Earth, the Sun shows many signs of being variable. We have good reasons to keep track of this activity, not least because violent solar phenomena can pose risks to some widespread technology. For an overview of ongoing solar monitoring, the NOAA maintains a real-time Space Weather Dashboard, which among other indicators includes a count of sunspots.

In visible light, sunspots appear as dark patches on the surface of the Sun (Figure 1) because they have lower temperatures than their surroundings, and they are directly linked to intense magnetic activity. The motivation behind today’s paper is that we could learn much more about the magnetic activity of other stars, if we could study their starspots in a similar way as sunspots. ...

The Starspots of HAT-P-11: Evidence for a Solar-like Dynamo - Brett M. Morris et al
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A different explanation for extra gamma-rays

Postby bystander » Fri Sep 01, 2017 2:34 pm

A different explanation for extra gamma-rays
astrobites | 2017 Aug 30
Kelly Malone wrote:
The center and disk of our Galaxy have received a lot of attention over the last few years. In addition to the well-known supermassive black hole and the recent report of a PeVatron in the area, there is an excess of gamma rays in the GeV energy range, seen with data collected from the Fermi Gamma-Ray Space Telescope. Gamma rays are the most energetic electromagnetic radiation. We don’t know yet what is causing this gamma ray excess; numerous papers have been written theorizing that this is the gamma-ray signature from dark matter annihilating, or alternatively that it is being caused by millisecond pulsars (Astrobites coverage of the latter hypothesis). Note that this excess consists of more gamma rays than we would expect just from the diffuse gamma-ray background.

Today’s paper explores a possible different origin of this excess – that the gamma rays are associated with interactions inside molecular clouds and they originate in the Galactic disk rather than the Galactic center (since we only observe the excess along our line-of-sight, it is non-trivial to determine the spatial origin). ...

Molecular Clouds as the Origin of the Fermi Gamma-Ray GeV-Excess - Wim de Boer et al
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Could Dark Matter be Black Holes?

Postby bystander » Fri Sep 01, 2017 2:45 pm

Could Dark Matter be Black Holes?
astrobites | 2017 Aug 31
Nora Shipp wrote:
The mystery of the nature of dark matter is deepening. Dark matter particles have evaded our detection again and again, bringing into question the most popular theories (like WIMPS), and thereby opening the door to more exotic and unexpected dark matter models. In the midst of this growing uncertainty, a new possibility has arisen. LIGO has detected gravitational waves resulting from the merging of two black holes. This may seem irrelevant to dark matter, but black holes are really not unreasonable dark matter candidates. They don’t emit light, and they definitely do interact via gravity, and those are basically the only two things we know about dark matter. ...

Did LIGO detect dark matter? - Simeon Bird et al

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Simple recipe for the final spin of a binary black hole coalescence

Postby bystander » Mon Sep 04, 2017 8:45 pm

Simple recipe for the final spin of a binary black hole coalescence
astrobites | 2017 Sep 01
Lisa Drummond wrote:
On the fourth of January this year, another gravitational wave signal from the coalesence of two black holes (GW170104) was detected by LIGO. (Read more about the detection here.) Interestingly, the newest detection unveiled clues about the spin of the individual black holes: at least one of the spins was likely in the opposite direction to the orbital motion. The model in this paper gives us insight into the precise way the final black hole spin relates to properties of the individual black holes. ...

Estimating the final spin of a binary black hole coalescence - Alessandra Buonanno, Lawrence E. Kidder, Luis Lehner
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X-ray eyes on a Wolf-Rayet nebula

Postby bystander » Mon Sep 04, 2017 8:53 pm

X-ray eyes on a Wolf-Rayet nebula
astrobites | 2017 Sep 04
Kerrin Hensley wrote:
As very massive stars evolve off the main sequence, they sometimes lose more than half their initial mass through dense, slow winds. The stars’ hot cores are laid bare, emitting copious ultraviolet photons that ionize the expelled material, which forms an optically-bright bubble-shaped nebula. The exposed hot core is referred to as a Wolf-Rayet (WR) star, while the discarded outer layers that surround it make up what is known as a Wolf-Rayet nebula. These objects are named after the pair of French astronomers who first discovered them via their unusual spectra, which feature broad emission lines jutting above the continuum. While WR stars are readily detectable (even out to nearby galaxies) because of their unusual emission-line spectra, the origin of the surrounding nebulosity is more difficult to pinpoint because of its close resemblance to other types of emission nebulae, especially planetary nebulae, and the interaction of the ejected material with the interstellar medium.

Theory suggests that WR nebulae should emit X-rays. After a star loses its outer layers and becomes a WR star, its stellar winds accelerate to ~1500 km/s—more than ten times the previous pace. These faster winds collide with the previously ejected material propagating into the interstellar medium. This process should generate a diffuse bubble of shocked material that should emit in the X-ray, but this predicted X-ray emission has proved elusive; only a few WR nebulae have been detected in the X-ray. In this paper, the authors use narrow-band optical images and X-ray images and spectra to investigate the properties of the area surrounding WR 18, a Wolf-Rayet star closely associated with emission nebula NGC 3199. ...

Hot Gas in the Wolf–Rayet Nebula NGC 3199 - J. A. Toalá et al
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The WTF Star Strikes Again

Postby bystander » Sun Sep 10, 2017 5:51 pm

The WTF Star Strikes Again
astrobites | 2017 Sep 05
Emily Sandford wrote:
Boyajian’s Star loves the limelight. It splashed onto the astronomical scene in 2015 by dimming dramatically and messily, much more messily than can be explained by a transiting planet. In 2016, astronomers realized that this sensational debut was only the latest act in a century-long fade, confirmed by exquisite observations from the Kepler mission. And the drama keeps building–just this summer, Boyajian’s Star has undergone (is undergoing!) three more dimmings, similar in shape to the dimmings reported in 2015.

This week, Boyajian’s Star is back in the news again, the subject of two new studies. The first confirms that the slow fade observed by Kepler is happening across a broad range of colors. The second, which we’ll explore in today’s bite, points out that this consistent fade might not be so consistent after all. ...

Where Is the Flux Going? The Long-Term Photometric Variability of Boyajian's Star - Joshua D. Simon et al
Extinction and the Dimming of KIC 8462852 - Huan Y. A. Meng et al

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Forming Planetesimals in A Dust and Gas Vortex

Postby bystander » Sun Sep 10, 2017 6:30 pm

Forming Planetesimals in A Dust and Gas Vortex
astrobites | 2017 Sep 06
Mara Zimmerman wrote:
Planet formation still holds many mysteries for today’s astronomers. One of the biggest unknown is how pebbles and dust clump together to form planetesimals rather than drifting in towards the star due to its strong gravitational pull. A possible solution is dust traps—in a circumstellar disk, the pebbles and particles’ drift inwards can be stopped by high pressure in thegaseous disk. A dust trap like this would be an ideal place to form planetesimals. The authors of today’s paper look at a circumstellar disks around AB Aur . They create hydrodynamical simulations of the dust and gas to see if there is a dust trap with the possible formation of small planets. ...

Probing the Cold Dust Emission in the AB Aur Disk:
A Dust Trap in a Decaying Vortex?
- Asunción Fuente et al
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The Mass Controversy of Retired A-Stars

Postby bystander » Sun Sep 10, 2017 6:39 pm

The Mass Controversy of Retired A-Stars
astrobites | 2017 Sep 07
Matthew Green wrote:
There’s an old saying, sometimes called Segal’s Law: “A person with one watch knows what time it is; a person with two is never sure.” Today’s paper concerns a similar problem in astronomy. The authors were measuring the masses of a certain group of red giants called “Retired A-Stars”. They find that these stars are less massive on average than previous measurements which used different techniques, enough to suggest that there’s a problem– either with the technique used in today’s paper, or with the previous technique. ...

Asteroseismic masses of retired planet-hosting A-stars using SONG - Dennis Stello et al
Know the quiet place within your heart and touch the rainbow of possibility; be
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A history of water loss in the TRAPPIST-1 exoplanets

Postby bystander » Sun Sep 10, 2017 6:56 pm

A history of water loss in the TRAPPIST-1 exoplanets
astrobites | 2017 Sep 08
Leonardo dos Santos wrote:
In early 2017, people quickly turned their attentions to TRAPPIST-1, a seemingly run-of-the-mill M dwarf star in the constellation of Aquarius, owing to the discovery that it hosts seven exoplanets and of which several are inside its habitability zone (HZ). After a careful look at the ultraviolet (UV) spectra of the star during a planetary transit and out of transits, V. Bourrier and collaborators discovered a variability that could be traced to the history of water escaping from the TRAPPIST-1 planets. ...

Temporal Evolution of the High-Energy Irradiation and Water Content of TRAPPIST-1 Exoplanets - V. Bourrier et al

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