Saturday, August 29, 2015

Index by Topic





Planetary systems across the Milky Way. Credit: M. Kornmesser, ESO
(full-size image available here)

Years in Review


Six new or resurrected exoplanetary systems within 20 parsecs, including a low-mass planet around the nearest star, a Solar System analog less than 8 parsecs away, and the return of Rho Coronae Borealis
 
A Super Jupiter for Aldebaran, a gas dwarf for the Hyades, terrestrial planets around Kepler-138, subterrestrials around Kepler-444, and the continuing mystery of Hot Jupiters
 
2014: A Year of Small Wonders (1/4/15)
Water vapor over HAT-P-11b, conjoined planetary systems, another candidate for Earth 2, and more

Kepler finds the Holy Grail, goes hooey-bluey, and morphs into K2

More circumbinary planets, plus rumors of a Hellworld around Alpha Centauri B

Celebrating the Kepler revolution in exoplanetary astronomy

Solar System

A look at two different explanations for the unusual architecture of the inner Solar System

A third explanation for the unusual architecture of the inner Solar System, with a forceful refutation of the previous two 

Evolutionary Twist (12/19/15)
A new study questions the ability of the Nice Model to explain the architecture of our Solar System

Four Fabulous Dwarfs (7/21/15)
Notes on the Dawn and New Horizons missions to the dwarf planets Ceres and Pluto, with plenty of photos

Evidence for an ancient ocean covering the northern hemisphere of Mars

Notions of a life-friendly Hadean Eon are challenged by a new view of the Late Heavy Bombardment

The evolution of our Solar System, from its birth in a huge star cluster to the formation of Jupiter and Saturn

The later phases of our system’s evolution, including the Grand Tack and the Late Heavy Bombardment

Spoiler alert: it’s REALLY weird and nobody knows why

 The Sun and the eight planets at their relative sizes

The Sun's Back Yard

The Nearest 20 Parsecs (3/27/16)
An overview of planetary systems in the Sun's immediate neighborhood
 
Potential formation scenarios and habitability of Proxima Centauri b, a terrestrial planet just discovered around the nearest star to our Sun

The Ghost in the Window (10/31/15)
Alpha Centauri Bb is shown to be a ghost instead of a real planet, while two of the six planets proposed for HD 40307 have no support in the data

A transiting Super Earth for HD 219134, only 21 light years away, plus musings on planetology and system architectures

Another group of astronomers looks at this remarkable system and finds six planets instead of four
 
A third group of astronomers looks at this remarkable system and confirms only four planets

A new study finds only three planets, and none of them are in the habitable zone
 
A new study finds only two planets, and none of them are in the habitable zone

A rosy view – since superseded – of the planetary system proposed for GJ 667C, a nearby M dwarf
 
A closer look at the evidence for Alpha Centauri Bb

A team using the HARPS spectrograph reports the marginal detection of a Hellworld orbiting Alpha Centauri B
 
Just when we thought we knew our neighbors, we find out we’re wrong again
 
An overview of the space within 10 parsecs, focusing on controversies involving Epsilon Eridani, Fomalhaut, GJ 581, and GJ 667C
 
More Distant Exoplanetary Systems

New radial velocity data confirm a sixth non-transiting planet in this benchmark high-multiplicity system

HIP 41378: Compact Planet Sampler (7/10/16)
A high-multiplicity mixed-mass system discovered by K2

1,284 New Kepler Planets, None Like Earth
The latest release of Kepler data reveals a lot of well-baked but lonely little planets

Almost Jupiter (3/20/16)
Kepler-167, a mixed-mass system where all planets are observed in transit, inspires another look at Jupiter analogs
 
New data significantly revise the parameters of the system’s six planets

The first circumbinary system with two planets, one smaller than Neptune

Kepler-38b, the fourth circumbinary planetary system to be announced

An overview of the exoplanetary zoo, focusing on planetology and system architecture, just as the census passes 900 confirmed extrasolar planets
 

 Planets across five orders of magnitude in mass

Planetology

K2 and the Tweens (7/4/16)
The K2 Mission has been reporting some very interesting planets 

A summary of constraints on the characteristics of planets that could support water and life
 
Daydream Destinations, Part 1 (4/9/16)
Exploring speculative fiction for insights into possibly habitable planets in binary systems, with nods to Battlestar Galactica and Firefly

Daydream Destinations, Part 2 (4/14/16)
Continuing our cruise through fantastic films and literature for insights into the potential environments of exomoons and tidally locked planets
The latest release of Kepler data shows that small planets are more numerous than gas giants in our Galaxy
 
Understanding the bloated radii of so many small Kepler planets

Reality check on current concepts and nomenclature for planets smaller than Uranus

A review of the theories that gave us Super Earths, plus a pitch to use the term “gas dwarf” instead of Super Earth or Mini Neptune for all those puffy little Kepler planets

A growing number of transit detections reveal exoplanets smaller than Earth

System Architecture

An overview of the Sun's immediate neighborhood, plus comparisons between the local exoplanet population and two other samples: radial velocity detections between 20 and 200 parsecs and Kepler discoveries at all distances

Almost Jupiter (3/20/16)
Kepler-167, a mixed-mass system where all planets are observed in transit, inspires another look at Jupiter analogs

Evolutionary Twist (12/19/15)
A new study tries to explain the architecture of WASP-47 by in situ formation

The Blazing WASP-47s (8/29/15)
The first Hot Jupiter with not one but two close companions in an ultra-compact design

A rare example of conjoined planetary systems, the only known pair in which both stars host Hot Jupiters

Suddenly we have a respectable sample of compact multiple systems containing both gas giants and low-mass planets – and we need a theory to explain them

Giant planets appear inimical to the survival of nearby objects in the mass range of Mars to Uranus, a situation with major implications for system architectures and the existence of habitable planets

A modest proposal for categorizing planetary systems according to three basic architectural types

On the critical role of planet mass in system architecture

A critical look at the concepts of "Solar System analogs" and "Jupiter analogs"

System Evolution

An introduction to current theories on the formation and evolution of planetary systems

Protoplanetary Disks and In Situ Formation (11/5/16)
Fundamental data on the short-lived clouds of dusty gas where planets are born, plus a review of the theory of in situ formation

Accumulating evidence that the evolving structures of protoplanetary disks offer a template for system architectures

Evolutionary Twist (12/19/15)
A new study questions the ability of the Nice Model to explain the architecture of our Solar System

Notions of a life-friendly Hadean Eon are challenged by a new view of the Late Heavy Bombardment

The evolution of our Solar System, from its birth in a huge star cluster to the formation of Jupiter and Saturn

The later phases of our system’s evolution, including the Grand Tack and the Late Heavy Bombardment

Earth 2

A summary of constraints on the characteristics of planets that could support water and life 

Kepler-452b: Latest Hope for Another Earth (7/26/15)
The latest candidate for Earth 2 does not impress

Guess what: Kepler hasn’t actually found any Earth-like planets orbiting Sun-like stars

Our first look at Kepler-438b and Kepler-442b, and a look back at the other candidates

The discovery of Kepler-186f, described as a potentially habitable Super Earth

The discovery of Kepler-62f, described as a potentially habitable Super Earth

Parsing the Kepler team’s remarks about Earth-like planets orbiting Sun-like stars



Four NASA photographs of our planet scaled according to the mass-radius relationships of Unterborn et al. (2016). For perspective, one photogenic but out-of-range object – Mars – is included at far left.
 
This index of blog posts on Back Alley Astronomy is regularly updated to enable easy access to extensive content on extrasolar planets and planetary systems.

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