OCTOBER 2012 ISSUE

Planetary Geology

The Sky at Night

Asteroid Impacts

Pages 4-5

Pages 8-9

A three part special on Planetary Geology from our geology expert Emma Quinlan

Editor: Chloe Partridge

Copy Editor: Martin Griffiths

Contributors: Emma Quinlan, Helen Usher, Terence

Murphy

Columnists: Phill Wallace, Martin Griffiths

If you would like to contribute in any way, either by

sending us your Faulkes images, or perhaps even writing

an article , then get in touch, we would love to hear from

you.

Editorial Contacts :

10017607@glam.ac.uk

mgriffi8@glam.ac.uk

IMAGE REFERENCES:

PG 1. Tharsis Tholus — geochristian.wordpress.com

PG 4-5. City Earthquake — www.pureanimegallery.com, Tidal wave — end-2012.com, Fireball — www.wikipedia.org, Acid rain —

www.gasdetection.com

PG 6-7. The Grand Canyon. - www.camperscircle.com, The surface of Venus - www.our-earth.net, The surface of Mercury. - discovermaga-

zine.com, The Martian sedimentary landscape - www.seasky.org

PG 8-9. All images Martin Griffiths, Sky Map — Heavensabove.com

PG 10. Pair of red dwarfs, Gliese 623 A and the tiny B.—C. Barbieri (Univ. of Padua), NASA, ESA

PG 11. Student, - herald.thehoweschool.org/

PG12. Newton — www.splung.com

EDITORIAL

Welcome back to another academic year of Glam UNI-

verse. I have no doubt that this year will be filled with

even more interesting articles and feature stories. To

kick off the start of another great year we have a three

part Planetary Geology special from our geology expert

Emma Quinlan. Emma has an amazing depth of

knowledge and passion when it comes to geology and

she has cleverly crafted a series of articles to talk us

through Planetary Geology, which we can look forward

to over the coming months.

In this months issue, as usual we have our death and

destruction themed article from Phill Wallace, and The

Sky at Night by Martin Griffiths—two articles which are

always a joy to read—as well as a tantalising article on

Red Dwarfs by Terence Murphy.

Some Observational Astronomy students have also

been taking part in STEM ( Science, Technology,

Engineering and Maths) based teaching work shops, in

local schools, and Helen Usher has written a lovely

account of her time introducing the Sun and our Solar

System to kids, in a fun and engaging environment.

Interesting science all round…

PS. For all the newbie Astronomers joining us, welcome

aboard the thought train that is BSc Observational

Astronomy… get stuck in.

O C T O B E R 2 0 1 2 I S S U E

GL

MA

OR

GA

N

AS

TR

ON

OM

Y

C O S M O L O G I C A L N E W S

8 - 9 . T H E N I G H T S K Y I N O C T O B E R .

W I T H A U T U M N N I G H T S D R A W I N G I N , W H A T I S V I S I B L E I N T H E O C T O B E R S K Y ? A R O U N D U P O F P L A N E T S M E T E O R S H O W E R S A N D

P O I N T S O F I N T E R E S T .

4 - 5 . A S T E R O I D I M P A C T S — O R , H O W

W E ’ R E A L L R O Y A L L Y D O N E F O R .

W E A L L K N O W A S T E R O I D I M P A C T S A R E A B A D T H I N G , B U T I T

T U R N S O U T T H E Y ' R E A L O T W O R S E T H A N W E T H O U G H T . R E A D O N

T O F I N D O U T W H Y . . .

6 - 7 . R O C K T Y P E S - S E D I M E N T A R Y .

E V E R H E A R D G E O L O G Y B E I N G L A B E L L E D A S B O R I N G ? W E H O P E T O P R O V E Y O U W R O N G ! G E T T I N G U P C L O S E A N D P E R S O N A L W I T H

P L A N E T E A R T H ’ S R O C K T Y P E S W E A R E F I N A L L Y A T T E M P T I N G T O

U N D E R S T A N D O U R P L A N E T A R Y S I B L I N G S A N D H O W T H E I R M A K E U P

D I F F E R S F R O M O U R S .

1 0 . R E D D W A R F S T A R S A N D T H E I R I N -

T E R E S T I N G N A T U R E .

R E D D W A R F S A R E U N J U S T L Y C O N S I D E R E D B Y M A N Y T O B E

S M A L L , R E D , C O O L , I N A C T I V E A N D U N I N T E R E S T I N G B E C A U S E

T H E Y A R E S L O W D E V E L O P E R S .

1 1 . A N A D V E N T U R E W I T H A G O L F

B A L L , A T O I L E T R O L L . . . A N D 1 3 0 K I D S .

A D A Y I N T H E L I F E O F S T E M A M B A S S A D O R H E L E N U S H E R A S

S H E H E L P E D O U T A T H E O L D D U C O M P R E H E N S I V E S C H O O L ' S

S C I E N C E W E E K .

6 - 7

8 - 9

1 0

4 - 5

1 1

Page 4 C O S M O L O G I C A L N E W S

We’ve all seen Armageddon. Those of us with

more taste have seen Deep Impact. We know

that a big rock from space hitting Earth is a

bad thing. Fortunately, in films there’s always

Bruce Willis in a dirty spacesuit to save the day

with a nuke and a heroic sacrifice, or

something similar. Sadly, we live in the real

world not fiction, and there are plenty of big old

rocks tumbling through space.

Luckily, no known large rock is going to hit us

within a thousand years or so, no need to

worry. But we know that rocks have hit Earth in

the past. The Cretaceous-Tertiary Event, which

rendered the dinosaurs extinct, was most

probably caused by one or more impacts in the

Yucatan region. A piece of rock just six miles or

so across wiped out a majority of species on

Earth. That’s staggering.

But it gets worse. Let’s take an example

asteroid and work out the damage potential. If

we assume a 30 km wide mostly silicon

asteroid with a density of 2700kgm-3, moving at

a 25 kms-1 velocity (fairly typical for Earth-

crossing objects), this asteroid would strike

the surface with a kinetic energy equivalent to

around three billion megatons. To put this in

perspective, imagine detonating a nuclear

bomb like Little Boy every second for six

thousand years and compress that all into one

blast. If that impact happened, every single

living thing within 3700 km would be

incinerated. That’s going to be a big insurance

bill.

Despite this massive damage potential, it’s a

common belief that asteroids do damage on a

global scale solely through loading the

atmosphere with dust and ash and blocking out

the sun, inhibiting photosynthesis and wiping

out the food chain. Now, that does happen, and

it is bad. But impact events have eight other

distinct damage mechanisms:

Asteroid Impacts – Or, how we’re all royally

done for!

Tokyo Earthquake

Page 5 O C T O B E R 2 0 1 2 I S S U E

B Y P H I L W A L L A C E

Ballistic Impact Ejecta: Any impact will launch

debris upwards on ballistic paths from the

impact site. Most of this debris is launched

upwards into space, where it will eventually fall

back to Earth, resulting in lots of smaller

impacts, although these hardly matter after a

really big impact. There is another, related

problem however. The passage of so much

hypervelocity debris up and down through the

atmosphere will generate massive friction,

heating the upper atmosphere (transparent,

remember, so the heat will spread easily). A

really big impact will heat the atmosphere above

1500K, which is enough to sterilise the planet.

Water Injection: An impactor can carry a

massive column of water and steam into the

upper atmosphere, this column could contain 10

to 30 times the impactor’s mass in water,

humidifying the upper atmosphere. We’re not

quite sure what effect this would have, but it’s

unlikely to be beneficial. Cloud particles forming

may reflect sunlight, which is bad, or cause a

runaway greenhouse effect, which is also bad.

Tsunami: The second-most-famous mechanism,

especially for smaller impacts. A large ocean

impact generates a massive wave that will

sweep across the seas until it hits land, finally

breaking tens or hundreds of miles inshore.

Particularly dangerous to humans since we

build next to the sea. In case of an impact

tsunami, getting some sea air is not good for

you at all.

Acid Rain: Passing through the atmosphere at

these speeds generates shockwaves that allow

chemical reactions to create massive amounts

of Nitrous Oxide, which will fall as acid rain

thousands of miles from the impact site. The NO

will also destroy the ozone layer and would take

many decades to be “scrubbed” from the air by

natural processes.

Electrodynamic interactions: A lot of ionised

stuff is moving around after an impact and this

ionic jet will interact with Earth’s magnetic field

to create a giant generator, altering the shape

of the magnetosphere and converting some of

the jet’s kinetic energy into thermal energy in

the atmosphere (as if it needed more heat after

an impact). This will destroy the ozone layer and

probably disrupt the van Allen belts, which

would probably be bad.

Impact Fireball: Exactly what it sounds like. The

impact will release massive amounts of kinetic

energy in the form of heat, superheating the

surrounding atmosphere and blasting it

outwards in the same way a nuke does, although

the fireball will be drawn up into the ionised

wake, making it more elongated than a nuclear

blast.

Wake Radiation: A massive hypervelocity

impactor passing through the atmosphere will

generate an enormous bow wave of

superheated and ionised gas in front of it and

will also leave a wake of superheated expanding

gasses behind it. This wake can be modelled as a

columnar explosion with similar effects to a

nuclear blast; shockwaves and intense thermal

radiation. Moreover, the nature of the fireball

means the thermal radiation will be propagating

through the upper atmosphere which is pretty

much transparent to thermal radiation,

resulting in much more widespread effects.

Impact earthquake: It’s a massive

hammerblow from space; of course there will be

seismic activity. Massive shockwaves

propagating through the crust would create a

vast area of destruction, far larger than the

fireball radius. This is particularly dangerous to

human civilisation due to our habit of building

large scale structures and sensitive facilities

such as nuclear plants, chemical storage

facilities and so on.

Suffice to say, an asteroid impact on a large

scale is a total game changer. Anything on a

massive scale will annihilate all life on Earth.

Any small impact will devastate whole

continents and end human civilisation, if not

existence.

Tidal wave

Impact fireball

Acid rain forest

Page 6 C O S M O L O G I C A L N E W S

Rock Types - Sedimentary

Let’s bring this back to basics. Geology is the

science of rocks and how rocks function to

form the planet we know as Earth. I love

geology, plain and simple. I will never cease

tiring of learning about our fascinating planet

and how she works. The most dog-eared

subject of Geology is undoubtedly rock types. I

can hear a collective groan amongst my fellow

students as they sleepily listen to another

lecture on rock formation. Bear with me, there

is light at the end of the tunnel.

The rock types of Earth are diverse

and complex. Their most amazing feature is

their variety. Rocks are composed of many

different minerals, volatiles and crystals

depending on how and where they have been

formed within the Earth. Understanding these

rock types gives us a great insight into our

own planet and also the surfaces of the many

other planets which litter our solar nursery.

There are three main rock types, Sedimentary,

Metamorphic and Igneous. So, shall we start

with the most basic; Sedimentary?

Sedimentary rocks are created through the

process of erosion of surface rocks on a

planet. Erosional processes can be fluvial

(water/river) or aeolian (wind) in nature. For

sedimentary rocks to form, erosional

processes must take place to breakdown the

existing bedrock. The composition of planetary

bedrock in its original state is usually igneous

rock. This is due to how the planet forms and

cools leaving a solidified igneous crust.

However, on Earth erosional processes

continually recycle the bedrock through the

rock cycle and therefore the bedrock can also

be sedimentary rock. Through the methods of

erosion, previously formed rock gets beaten

and weathered until they are no more than just

sand and grit. These sediments are layered on

top of one another where they are compacted

by their combined weight and pressure to form

sedimentary rocks. These rocks are unique as

they have not been affected by internal heat

and pressure, unlike metamorphic and igneous.

The terrestrial planets all have weathering

processes by which they can recycle their

bedrock. However, can the terrestrial planets

actually form sedimentary rocks through these

processes and can we see this in action?

The only erosional process which takes place

on the innermost terrestrial planet is aeolian.

Mercury suffers from extreme solar battering

due to its closeness to the Sun and its weak

atmosphere, which results from a weak

magnetosphere. Throughout the formation of

the solar system and up until now, Mercury has

had to defend itself from extreme solar winds

and coronal mass ejections (CME’s), which

strip the planet of its bedrock. This makes

Mercury an uninhabitable planet. It also

restricts the types of rocks that can form on

Mercury. It is safe to say that Mercury

possesses none of the erosional requirements

to create sedimentary rock and the likelihood

of there being any type of this rock is

extremely slim.

Earth’s greatest sedimentary feature, The Grand Canyon.

The surface of Mercury. The bedrock

has been eroded away.

O C T O B E R 2 0 1 2 I S S U E Page 7

Venus, our nearest neighbour possesses

aeolian and fluvial processes. The presence of a

thick and dense atmosphere that can create

huge weather systems indicates a high

possibility of erosion and deposition. Although

this all sounds promising, if someone were to

actually go there, sedimentary rocks would not

be found. The makeup and composition of

Venus’ atmosphere is so corrosive that

sediments and dirt would not be able to survive.

Sulphuric rain and strong winds has corroded

the surface of the planet. Rock cannot form

when an atmosphere destroys its chances of

forming. Another rock type is present on this

planet where sedimentary rock cannot form.

Our own planet is the third terrestrial planet in

the solar system. Earth has the right processes

of erosion such as an atmosphere, rivers and

weather systems which allows a very diverse

range of sedimentary rocks to exist. The most

common Sedimentary rock is Limestone.

Distinctions between sedimentary rocks are

based on their strata (layers) and their

granular sizes. Granular sizes can be from a

grain of sand up towards a 2cm pebble. The

larger the matrix, the more conglomerate the

sedimentary rock is. Erosion takes place within

rivers, coastal areas and by aeolian

environments such as deserts. Due to our

steady atmosphere sediment layers can build

up and over time can produce stratigraphic

layers of sedimentary rock.

The last terrestrial planet is Mars. Mars is the

right distance away from the Sun to escape the

heavy bombardment that Mercury obtains

however it does share a weak atmosphere. The

atmosphere of Mars expands and contracts,

making it more susceptible to CME’s and solar

flares. Unlike Mercury and Venus, Mars

possesses polar ice caps which keep water

locked frozen for most of the year. When these

ice caps melt, the erosion which takes place is

fluvial. The abrasion of bedrock takes place by

broken glaciers moving in their warmer

migration in the summer months. The melt from

these glaciers produce liquid water that cuts

into the bedrock eroding channels into the

surface. The larger conglomerates are steadily

eroded by the fast flowing water and by

abrasion. We can determine that near the polar

ice caps Mars could produce sediments which

could form into sedimentary rocks. On the main

body of Mars weather systems produce aeolian

erosion. Huge dust storms are violently swept

across the land due to the recession of the

atmosphere. These wind systems pick up small

and large sediments within their bowls,

transporting them worldwide across the planet.

Abrasion also takes place in these wind tunnels

when the sediments and sand is intermingled

and collides together. In the past with a stable

atmosphere which was constant, Mars was able

to produce sedimentary rocks. However, in the

atmospheres current state of expansion and

contraction it is unlikely that Mars is producing

new sedimentary rocks.

To recap, Mercury and Venus are not and never

were stable enough to produce sedimentary

rocks. The only planet other than Earth to

produce sedimentary rocks is Mars. The

likelihood is that Mars is slowly losing the ability

to produce these rocks due to its weak

atmosphere.

I hope you have enjoyed learning about the

first and most basic rock type. The journey is to

be continued …

The surface of Venus. Corrosion of igneous rocks or sedimentary?

The Martian sedimentary landscape.

B Y E M M A Q U I N L A N

Page 8 C O S M O L O G I C A L N E W S

The Night Sky in October October sees the last of the summer constellations dominating the sky and the rise of the Autumn constellations of pegasus, Persues and An-dromeda, along with the barely discernible groups of Aquarius, Cetus and Pisces. The Orionid meteor shower, associated with the debris of Hal-

ley’s comet may give a reasonable showing – weather permitting.

Moon In October:

First quarter: 22nd October

Full: 29th October

Last Quarter: 8th October

New: 15th October

Cetus is the largest constellation in terms of area in the Autumn sky, and is an amorphous

collection of faint stars that mark the boundaries of the fabled "Sea Monster" that was sent to

attack the beautiful Andromeda to compensate for the boasting of her mother, queen Cassiopeia.

Thankfully, the hero Perseus was on hand just in time to save the fair maiden. He killed the sea

monster by showing it the decapitated head of the Gorgon Medusa, thus turning Cetus into

stone. Poseidon incensed that his monster was dead, then placed it in the sky, in a position where

it could still threaten Andromeda, and roar its

disapproval at Perseus. On old star maps, Cetus

is always portrayed as a whale, with huge teeth and frightful appearance, which belies the nature

of these gentle creatures. Big, was obviously not

always beautiful to the ancients.

Cetus contains a few objects of interest to the

casual observer, but unfortunately, its low alti-tude as seen from Britain tends to water down

the brilliance of some of them and adds one or two magnitudes to others. Identifying the group

is not difficult; simply look for the head of the monster, which is the most easterly part of the

constellation. Its 5 stars mark out a round outline from which it is relatively easy to figure out the

rest of the constellation as it spreads south and westwards. Cetus contains the beautiful variable

star "Mira", the typical object of this type of celestial wonder, in addition to several galaxies

that lie within the range of amateur telescopes.

The sky in October: The sky as it would appear at 22:00 on

the 1st

Planets in October

Mercury: is low in the pre-dawn sky and is

close to Saturn on the 6th of the Month. It is

moving toward inferior conjunction with the

Sun.

Venus: Is a brilliant morning object located amongst the stars of Leo and shining at magni-

tude -3.9. The planet is just a tenth of a degree

from Regulus on the 3rd October

Mars: is in the constellation of Libra and is very

close to the sun still after sunset so little ob-servation of this enigmatic planet can be made

this month as it is very low on the SW horizon.

Jupiter: Is in Taurus and is

wonderfully bright, shining

at magnitude -2.3 and almost visible all night, rising a short time after sunset. The moon is

only 1 degree south of the planet on the 5th of

the month.

Saturn: is in conjunction with the sun on the 25th October and is not well placed for observa-

tion this month.

Uranus: is still located in Pisces and is an

evening object shining at magnitude 5.7 after its opposition earlier this year. It should be

visible as a distinctly green white ball with

moderate magnification.

Neptune: Is an evening object in Aquarius with a magnitude of 7.9. A high magnification should

reveal a small blueish ball of light. Constellation of the month: Cetus

Page 9 O C T O B E R 2 0 1 2 I S S U E

M57 The Ring Nebula B Y M A R T I N G R I F F I T H S

The best deep sky object in Cetus is the Sb type spiral galaxy M 77, a tenth magnitude smudge of

light just under the "chin" of the monster. It is not an easy object in binoculars, but it may be seen

on a good night as a faint glowing mass of grey light 60 million light years away. M 77 is a very

unusual galaxy, one of the closest of a type known as "Seyferts", after the astronomer Carl Seyfert

who made a study of their ultraviolet excess and

their violent nuclei in the 1940's.

Seyfert galaxies are mostly spiral types charac-

terised by very bright nuclei in proportion to their

spiral arms, and also the peculiar presence of emission lines in their spectra. Further study of

these galaxies has revealed that there is a tre-mendous amount of energy flowing out of the

core of these objects, originating from a very small space at the centre. They are also radio

galaxies, and some are also visible in both x-rays and ultraviolet light, evidence of intense activity,

the source of which is postulated to be a Black Hole. Astronomers think that a black hole of sev-

eral million solar masses is shredding stars and

gas within these galactic nuclei, and ejecting some of it into space where it collides with the

interstellar and intergalactic medium, creating a shock wave which causes such intense radiation.

Seyfert galaxies are thus related to radio galax-ies and Quasars, being a little lower down the

energy scale.

Galaxies worth seeking out are NGC 157 and

NGC 908, two galaxies with a magnitude of 11,

so don’t expect to see them that well as in a

small telescope they will merely be little

smudges of light, and all but invisible in binocu-

lars. NGC 157 is an Sc type spiral lying 65 mil-

lion light years away, which looks a little elon-

gated in a low power eyepiece. NGC 908 is an

Sc type spiral at a similar distance to NGC 157

and is a little fainter than it. Both galaxies these

can be viewed but their arms will be a dull haze

with a faint core. The flagship of the constella-

tion is of course the beautiful red giant star

Omicron Ceti, or Mira as it is commonly known.

This name was given to the star by Hevelius,

and it was the only variable star known for

quite some period of time. The name means

"Wonderful", and many observers will agree

that it deserves its name. Mira can be seen on

any Autumn night even when at minimum as it

varies between magnitude 4 and magnitude 9 in

a period of 331 days.

On occasion, Mira becomes a lot brighter; during the late eighties the star was a brilliant naked eye

object shining at second magnitude, and trans-formed the Autumn sky with its incredible orange

glow that was plain to see. The spectral type is M, and the distance is roughly 220 light years, which

is relatively close for such a star. Over 4000 Mira type long period variables are known, most

of which have periods between 250 and 400 days, thus making convenient distance indicators,

as most of these giant stars have a similar intrin-

sic luminosity.

Mira is a very large star, probably around 300 times the diameter of our Sun, and one of only

three stars in which spectral bands of water vapour have been found. At minima, the star

switches most of its energy output into the infra-red part of the spectrum as it becomes an in-

tense red colour and the surface temperature drops to only 1800 degrees Kelvin. Its oscillations

can be followed in binoculars or a small telescope and is an ideal object to introduce the amateur to

the vagaries of variable star observing.

One star of interest within Cetus is the third

magnitude Tau Ceti. It is not a binary system or variable, but is a G type star of almost the same

dimension and luminosity as our Sun. Tau Ceti is only 11 light years away, and due to its Sun like

qualities was picked as a target for the SETI pro-gramme, the search for extraterrestrial life. It is

not known if Tau Ceti has a planetary system, but all the evidence points to it being a single star,

which according to the rules of physics, must

have lost a lot of dust and gas during formation as angular momentum propelled material away

from the formative nebulae, so it could have planets similar to those of our solar system. No

telescope yet built will show these planets howev-er, so we will have to await any reply to our radio

signals to confirm their presence. As yet no one

has answered.

One system that does have planets however is

a magnitude 6.7 star just to the west of g Ceti. This system, HD 16141 is a GIV type system with

one planet with a mass of 30% that of Jupiter

orbiting the star in 75 days at a distance of 0.36 AU. The star and its attendant plant is just

over 100 LY away and will require binoculars to spot the star, although this is les difficult that

other systems due to the dearth of stars in this area of the Autumn sky. Another extrasolar

planetary system is that of HD 19994, right on the Cetus / Eridanus border. The star is an F8V

spectral type lying 70 LY away and visible on The Sky and Sky Atlas 2000. The planetary

system has just one known body with a mass

twice that of Jupiter orbiting at 1.3 AU from the star with a period of 454 days. The coordinates

are RA 03h 12m 46s Dec -01 11m 45s and the magnitude is 5.1, making this a naked eye object

and an easy star to spot in binoculars.

Cetus contains little else of interest to the ob-server with modest equipment, although owners

of large telescopes will have a red letter day with the dozens of galaxies visible in this area, most of

which are around 12th magnitude and are good candidates for the scrutiny of the supernova

patrol. Browsing through a good star atlas will

give their positions against the star of this large

constellation.

Page 10 C O S M O L O G I C A L N E W S

The classification of stars into different types was started toward the end of the 19th Century

and persisted through until the beginning of the 20th when Annie Jump Cannon at Harvard rear-

ranged the previous nomenclature so as to produce the basic Harvard Classification System

still used today. Stars were grouped into sections that were

distinguished by their surface temperature, although this was not known until some time

later. The Harvard groups are O B A F G K and M. So O type stars have a surface temperature

above that of about 33,000 Kelvin whilst M stars

have a temperature below about 3,700 Kelvin. Stars with such surface temperatures can be

comparatively big as per Red Giants, or compar-atively small as in Red Dwarfs. The spectral lines

observed in their light easily distinguishes be-tween the two.

The determination of a Stars mass and volume is

still quite a difficult problem and the fact that we know these parameters for as many stars as we

do is a testament to the ingenuity, intelligence

and persistence of generations of astronomers. So, we now know that there are very many red

dwarfs in our own galaxy and presumably in other galaxies too.

The prime difficulty in observing red dwarfs is

that they are small, cool and hence dim. The absolute magnitude of Proxima is +15.5 and at a

distance of 4.2 light years its apparent magni-tude is +11.1, much too dim to be seen without

optical aid. An M5.5 red dwarf like Proxima Cen-tauri has a mass some 12% that of the Sun and a

radius some 14% of the Sun. The radius scales

to the volume in a cubed fashion so that Proxima has a volume only 1.5 times that of Jupiter.

This tells us that the density of Proxima is some-thing like 40 times that of the Sun.

This is primarily because the gravity of the ma-

terial in the star balances the energy outflow from the fairly low level of thermonuclear reac-

tions in the core at a point where its density is this value.

The escape of heat energy in M-type red dwarfs

is interesting too. The forces and temperatures involved result in

the whole body of the star undergoing convec-tive movement unlike stars like the sun where

only the outer layers undergo convection. This convective motion results in the Helium

product of Hydrogen fusion being mixed-in and

swept away from the core. New Hydrogen then replaces this Helium and the core continues its

fusion as if no Helium had been produced. One consequence of this mixing is that no build-up of

Helium will occur. Between this and the fact that Hydrogen fusion proceeds at a slow rate the

lifetime of an M-type dwarf is very long indeed. The actual lifetime of Proxima will be some-

where between 1000 and 4000 billion years. The Universe is only 13.7 billion years old so

according to this every red dwarf that has ever

formed will still be out there. This does not in-clude red dwarfs that are in very close binary

partnerships with other stars where mass-transfer or merger has or will take place.

No wonder then, that we find red dwarfs wher-ever we look, to the limit of observability.

It has been estimated that 80% of the stars in

the Milky Way are red dwarfs and if we want to find lots of planets around stars then we need to

look closely at red dwarfs. The great quest is to find Earth-like planets in

the so-called Goldilocks zone.

One of the problems with habitable planets around small stars is that the smaller the star

the closer in and narrower is the habitable zone. The narrower the zone the less likely it is that a

habitable planet will be found there.

Another problem is that the closer the planet is

to the star the more likely it is that the planet will be tidally-locked into an orbit that is in a 1 : 1

ratio with its spin or in a 3 : 2 ratio like Mercury is with the Sun.

In either case the radiation from the star pro-duces areas of heating on the planet that will

find it difficult to dissipate heat in a requisite time resulting in permanent or slow-moving

hotspots that would not be conducive to life.

Small stars that are dense and fully convective produce magnetic fields that are proportionately

greater in magnitude than larger stars. This results in magnetic outbursts or flares that can

be unpredictable in time and duration and that encompass the full spectrum from radio waves

to x-rays. On Proxima these flares can increase the stars luminosity by a full magnitude (i.e. 2.5

times). Such large and fast changes present another challenge to life.

All of these possible problems will not stop us investigating red dwarfs. There are so many of

them and, being small, the radial velocity method for planet detection works so very well.

Red dwarfs do have planets and we will find them in large numbers.

There is so much to learn that I can hardly wait.

Red Dwarf stars

and their

interesting nature

T E R E N C E M U R P H Y

Pair of red dwarfs, Gliese 623 A and the

tiny B.

Page 11 O C T O B E R 2 0 1 2 I S S U E

One of the reasons I signed up to the Observa-

tional Astronomy Course (as a mature student)

was to get involved in outreach/schools work.

So when the STEM newsletter asked for volun-

teers to help out with a science week at my local

comprehensive school I offered my services.

The science week was in June so I thought that

doing some demonstrations with some solar

scopes would be appropriate and fun. The head

of science thought this was a good idea and I

popped up one morning to show her what I had

in mind. We set up in the yard at the centre of

the school and the teacher enjoyed looking and

seeing sunspots and flares (first success!). The

curiosity of staff and pupils alike soon became

apparent as people loitered as they passed to

see what was going on... and we gave a few

more their first view of the solar disk, to lots of

oohs and aahs (second success!). So a full day

of solar viewing and associated activities was

planned for the Friday. I borrowed scopes and

mounts from Martin to supplement my equip-

ment and briefed the lab assistants at the

school for their role in ensuring safety.

So Thursday night was spent putting together a

Plan B for how to entertain and inspire 5 forms

of (about 30) 12-14 year olds for an hour each in

a classroom. The teacher gave me a lead by

saying that they'd be interested in the solar

system. So after some hours of googling and re

-reading my planetary science course notes

(thanks Paul!) I had a presentation with anima-

tion on the solar system. Good, but....I was

afraid that expecting kids to sit still for an hour

while being lectured by a novice was unlikely to

be that inspiring or memorable. So more goog-

ling for help with activities. I was looking for

ways of getting over the scale and distances

involved. So, the golf ball was used as the earth

and I asked the class to estimate how big the

sun would be on the same scale - the answer as

it turned out was about the size of the class-

room - and how many earths would fit in the sun

(its about a million for reference). Then to dis-

tances. I'd seen a few ideas for setting up in the

school playground, and I'm sure it would have

been fun, but lashing rain and 30 kids didn't

really appeal to me. So instead there was a

toilet roll! This worked well for a couple of rea-

sons. Firstly it really got the pupils' curiosity

when they walked into the class to see me roll-

ing up a toilet roll (a first for them I think).

Secondly, it got a lot of them involved as I need-

ed one per planet and the sun. The scale for the

distance was that one sheet of toilet paper was

the distance between the sun and mercury.

They unrolled the toilet roll around the class and

stood at the relative positions of the planets

marked by names on the toilet roll. The kids

were clustered at the front close to the sun,

while poor Pluto (left in despite of its demotion)

was in the far back corner looking pretty lonely!

(We did need a few bits of sellotape to repair the

solar system during the day as I must admit I

didn't use the 'soft and strong' brand).

How did it go? The pupils got really engaged,

which was a relief. The majority were clearly

interested and asked really good questions. I

was most worried about the questions I'd get

asked as kids seem to retain facts so much

better than people of my age, but thankfully I

could answer all but one. They also liked getting

involved and I was never short of volunteers.

The teachers were also very interested, and I

provided some extra background materials for

them to use in the future. The feedback was that

everyone had thoroughly enjoyed it.

What did I learn? When I first stood in front of a

lab full of 30 13-year-olds I remembered why I'd

decided to be an accountant rather than a

teacher! But as I got into the swing of it I re-

membered why I now wanted to get involved, as

I really enjoyed seeing the kids getting inspired

by astronomy.

The plan is go back to the school when the

weather permits and set up the scopes in the

playground again. And I'm hoping to be there

again in Science Week next year - hopefully with

rather better weather.....

B Y H E L E N U S H E R

An adventure with a golf

ball,

a toilet roll...and 130 kids

BSc (Hons) Observational Astronomy

I can calculate the motion of heavenly

bodies, but not the madness of people.

-Isaac Newton