The RASNZ Email newsletter is distributed by email on or near the 20th of each month. If you would like to be on the circulation list This email address is being protected from spambots. You need JavaScript enabled to view it. for a copy.

Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website in their own newsletters provided an acknowledgement of the source is also included.


1. Tinsley and Pickering Honoured with Mountain Names
2. Nancy (Nan) Amelia Thrush (1916 - 2010)
3. The Solar System in February
4. 2011 Yearbook Moon Tables Wrong
5. 2011 Subscriptions Now Due
6. Stardate South Island
7. Earth and Saturn Photos on the Web
8. Astro-Photography Section's Yahoo Group Closing
9. Implications of Earth Observation in New Zealand
10. Royal Society of NZ Award Applications Sought
11. RASNZ Conference 2011
12. Odyssey Orbiter Passes Martian Longevity Record
13. Metals in the Mantle Tell How Planets Formed
14. Cepheid Mass Measured
15. Gifford-Eiby Lecture Fund
16. Kingdon-Tomlinson Fund
17. How to Join the RASNZ
18. Here and There

1. Tinsley and Pickering Honoured with Mountain Names

The New Zeland Geographic Board has announced that "Mount Pickering" and "Mount Tinsley" are now official geographic names.

Mount Pickering - a prominent mountain, at height 1650 m, located in the Kepler Mountains 20 km west of Te Anau. Topo50 map CD07 - Manapouri, GR 642 635. William Hayward Pickering (1910-2004), born in Wellington, was an engineer supporting rocket science for California´s Jet Propulsion laboratory, working on projects for NASA, including the unmanned space- flight programme.

Mount Tinsley - prominent mountain, at height 1537 m, located in the Kepler Mountains 15 km west of Te Anau. Topo50 map CD07 - Manapouri, GR 703 598. Beatrice Muriel Hill Tinsley (1941-1981), born in England and moved to New Zealand in 1946, was a prominent and highly-respected astronomer and cosmologist whose research in the USA made fundamental contributions to understanding the evolution of galaxies. Her married name was Tinsley, her maiden name was Hill.

The proposal to name these features was supported by RASNZ. We are pleased to see that Pickering and Tinsley have been recognised in this way and note that it is very fitting that these previously un-named mountains are part of the Kepler Mountains, a range named after 17th century astronomer Johannes Kepler.

-- Glen Rowe

William Tobin notes that the names were officially gazetted in Gazette-2010-Gazettes?OpenDocument probably issue No. 173 (16 December 2010), a 479 kB file.

On the RASNZ's webpage Brian Loader has put a map and photos of the mountains;

2. Nancy (Nan) Amelia Thrush (1916 - 2010)

The end of an era in Wanganui astronomy was reached on 16 November 2010, with the passing of Nan Thrush. Nan, (and Walter who died in 1985); represented six decades of astronomy in Wanganui, helping found the modern (second) Wanganui Astronomical Society and serving in executive positions on its committee for nearly fifty years!

Walter was President of the society and Director of the Ward Observatory from the mid-40s until the mid-70s, and also served on the Council of the RASNZ. Nan was Secretary of the Wanganui Astronomical Society for 48 years, finally retiring in the 1990s. She was elected as Patron of the Society in 1994; an honour as the position is normally held by the City Mayor. Indeed, the very name `Thrush´ is virtually synonymous with `astronomy´ in the River City.

Nan was born "up the river." in 1916, the oldest of five children. Her father was a carrier and ferryman on the river. The family eventually moved to Wanganui around 1920. It is unclear exactly when Nan became interested in astronomy, but her brother Ian believes it stemmed from meeting Walter and discovering a mutual interest.

Nan and Walter who were both committed Methodists, met at The Trinity Methodist Church, and were married there in 1939. They settled in Rata Street, which became a centre for astronomy in its own right. Unable to have children, they became mentors of a long succession of young keen amateur astronomers. Prior to the writer´s introduction to Nan and Walter, astronomers who had entered into the house at Rata St included Garry Nankivell, Norman Rumsey, Frank Andrews, Bill Allen, Stuart Mawson and Tony Messenger. These young men (then!) became affectionately known as `Nan´s Boys´. There have been many more in the intervening years. Most have gone on to make a name for themselves in the field of astronomy, and one or two have gone professional. Over the years, gatherings of young astronomers would spontaneously descend upon Rata Street, and avid discussions would develop, along with some gentle `stirring´ by Walter to keep things moving along.

Nan and Walter also hosted several notable professional astronomers passing through the city to give public lectures. Their commitment to publicising astronomy was very strong, and they spent enormous amounts of time encouraging anyone with even the slightest interest. In 1977 Walter and Nan were awarded the Murray Geddes Memorial Prize in recognition of their long-standing work encouraging interest in astronomy in the Wanganui area.

When I started in my first job at the radio station (then 2XA) in Wanganui in February 1962; being a dedicated amateur, I located the observatory close to where I worked, and joined the crowd at the Public Night. There I met Walter (and Nan the following weekend), became one of `the boys´; starting a long and very happy friendship which has lasted for almost 49 years. Over the years, the gravitational attraction of Rata Street worked its magic, and after leaving Wanganui and joining the RNZAF, based at Ohakea, I often found myself heading back to the city for meetings or to stay with Nan and Walter. They became second family for me. Many times after a meeting, Walter and Nan would either drop me south of the city to hitchhike back to base; or I would stay overnight and catch a bus back if I wasn´t required at work until mid-morning. When I married Lorraine in 1995, Nan naturally stayed with us at our house.

On one occasion in 1977 during my Mt John days, after being caught out in a bad snowstorm in Tekapo and suffering major after effects; I headed north to give a lecture at the Ward Observatory. It was Nan of course who nursed me back into a semblance of health and enabled me to give the talk. About eight years ago, while working on the night shift at the Taranaki Daily News, I came across a recent copy of the Wanganui Chronicle and discovered a picture of Nan looking very wry, and holding a set of car keys. It turned out that Nan had won a nice new car in a draw held by the Wanganui Savings Bank. Nan found the whole business extremely amusing and was vainly trying to keep a straight face for the photographer; the point being that Nan never learned to drive!

Nan and Walter´s association with The Trinity Methodist Church lasted to the very end; and Nan´s funeral service was held in the rebuilt church. Several of `Nan´s Boys´ were in attendance, and I was honoured by being asked by the family to be one of the pallbearers.

-- Rod Austin

3. The Solar System in February

The usual notes on the visibility of the Planets for February 2011 are on the RASNZ web site: Notes for March 2011 will be on line in a few days.

The planets in february

Jupiter is an early evening object low to the west; Saturn becomes a late
evening object to the east.  In the morning Venus rises early all month,
Mercury rises over an hour before the Sun at the beginning of the month.

Mars is at conjunction with the Sun on February 5 (NZ time). The planet will pass about 1 degree to the south of the Sun as seen from the Earth. Consequently Mars will be unobservable throughout the month.

The evening sky, JUPITER, URANUS and SATURN.

Jupiter will be low to the west following sunset during February. It sets about 2 hours after the Sun at the beginning of the month, dropping to just over an hour by the end. It will then be a difficult object in the evening twilight. Jupiter is in Pisces until the 25th when it moves into Cetus. The crescent moon will be 7 degrees to the lower right of Jupiter on the 7th.

As it moves to the east, Jupiter´s distance from Uranus will increase. The latter will set up to 20 minutes before Jupiter.

Saturn, in the opposite part of the sky, will rise before midnight in February, about 11.30 pm early in the month, advancing to a little before 10 pm by the end of February. Thus it will remain best seen in ...

The Morning Sky - SATURN, VENUS and MERCURY

Saturn ... the morning sky by early risers, especially at the beginning of the month.

The planet will be in Virgo, 8 or 9 degrees from Spica. Saturn will be the brighter object by about half a magnitude. In the morning sky, about an hour before sunrise, Saturn will be below Spica. At the beginning of February the two will be almost due north with Spica to the upper right of Saturn. By the end of the month the two will be to the north west with the star directly above the planet.

The moon, 3 days after full and 86% lit, will be 6.5° to the upper right of Saturn late in the evening of February 21 and the next morning 7.5° to the upper left of the planet, with the moon now 84% lit.

Venus will be the most obvious object in the pre-dawn sky, rising about three and a half hours before the Sun. The planet will be moving to the east through Sagittarius, a few degrees from the handle of the "teapot". Venus will be gibbous during February 61% to 71% lit.

At the beginning of February the asteroid (4) Vesta, magnitude 7.8, will be a few degrees to the east of Venus. The two will be moving to the east on close, parallel tracks. Within a few days, the faster moving Venus will catch up with Vesta, the two are closest during the evening of the 9th when they will be 22 arc-minutes apart, three-quarters of the diameter of the full moon. At that time of day they will not be visible from New Zealand.

As seen from NZ, on the morning of the 9th before sunrise, Venus will be 30 arc-minutes directly above Vesta. The following morning the two will be slightly closer with Vesta now to the left of Venus.

Conjunctions of the moon and Venus occur on January 30 and on March 1, there is none in February, although the moon will be 15 degrees above Venus on the last morning of the month.

Mercury will rise over an hour before the Sun during the first part of February, so may be visible low in the dawn sky. Forty minutes before sunrise it will be about 5 degrees up to the east-south-east and fairly bright at magnitude -0.4. Binoculars may show the planet in the morning twilight.

Like Venus, Mercury starts the month in Sagittarius. On the morning of February 1, it will be some 30 degrees to the lower right of the brighter planet, with the 5% lit crescent moon between them. The next morning the moon, now less than 2% lit, will be 4 degrees to the lower left of Mercury. If anything it may be easier to locate Mercury and use it to find the moon!

As the month progresses, Mercury will get closer to the Sun and so become completely unobservable. It is at superior conjunction with the Sun on the 25th when Mercury will pass about 2 degrees south of the Sun. It will also be about 4 degrees from Mars and 3 degrees from Neptune, which is at conjunction on the 17th. A grouping of the planets that will definitely not be observable.

Uranus, in the evening sky, will be lost in the twilight. By the end of the month it sets less than an hour after the Sun.

Neptune is at conjunction with the Sun mid February, so is unobservable.

Brighter asteroids:

(1) Ceres was at conjunction with the Sun at the end of January. By the end of February it will rise nearly 2 hours before the Sun, but at magnitude 9.2 is not likely to be readily visible in binoculars.

(4) Vesta, magnitude 7.8, will, as noted above, be in Sagittarius and passed by Venus early in February.

(7) Iris was at opposition on January 24 with a magnitude 7.9. In February it will be best viewed as an evening object. It fades quite rapidly, to magnitude 9 at the end of the month. At first Iris is in Cancer, but its retrograde motion takes it back into the south-east corner of Gemini on February 18.

More details and charts for these minor planets can be found on the RASNZ web site. Follow the link to asteroids 2011

-- Brian Loader

4. 2011 Yearbook Moon Tables Wrong

Due to a printing error the Moonrise/set tables in the 2011 New Zealand Astronomical Yearbook are wrong. The 2010 tables were repeated. The corrected Moon tables can be downloaded from the Stardome website at or printed copies are available from the Stardome Observatory, phone 09 624 1246.

5. 2011 Subscriptions Now Due

A reminder to all RASNZ members that subscriptions for 2011 are now due. If you have not already paid your subscription you have until 31 January to claim your $5 early payment rebate. Members may pre-order the 2012 yearbook when paying the subscription.

Amount to pay: - New Zealand Members $60, 2012 yearbook add $16.50 - Australian and South Pacific Members $70, 2012 yearbook add $23.00 - Members elsewhere $75, 2012 yearbook add $25.00 Reduce the above amounts by $5 if paying by 31 January

How to pay: - By cheque made out to "RASNZ" and mailed to:

The Treasurer,
Pauline Loader,
14 Craigieburn Street,
Darfield 7510, New Zealand

- By internet banking to the RASNZ account

ASB 123147 0384735-00

- By Credit Card via Paypal. Please visit

I have a limited number of the 2011 yearbook for sale - price to NZ members is $15.00 including postage. For overseas members the cost of 2011 yearbooks is $20 to cover additional postage.

If you have any queries about subscriptions or yearbooks please contact Pauline Loader mailto:This email address is being protected from spambots. You need JavaScript enabled to view it..

6. Stardate South Island

Euan Mason writes: Registrations for this year's Stardate South Island are going well. It will be held at Staveley between February 4th and 7th 2011. With a strong La Nina there is a high probability of clear skies, and we're featuring Phil Barker's new 17" Dobsonian, among other delights. Euan Mason will hold a hands-on session on solar viewing and Sunspot counts, followed by a guided tour of Peel Forest. If you are going to attend then make sure that you register. Here is the link:

7. Earth and Saturn Photos on the Web

Julie Wright passed on this link to a stunning collection of photos taken from the International Space Station

Phil Barker found this photo of the storm on Saturn. It was taken on Christmas Day through an 8-inch telescope in South Carolina. The link is

8. Astro-Photography Section's Yahoo Group Closing

After a recent survey and subsequent discussions with a number of people at Stardate, it would seem that some still want the option of a smaller, more technical astro-imaging Yahoo group.

At the moment there are two NZ groups: the RASNZ Astro-Photography Section (RASNZAPS) group and the NZ-Astrophoto group, besides the nzastronomers group. We decided to close the RASNZAPS Yahoo group -- but not the RASNZAPS itself -- and just have one, the NZ-Astrophoto group. The name NZ-Astrophoto group is easier to find in searches and is more self- explanatory.

So could those who are on the RASNZAPS group please join the NZ-Astrophoto Yahoo group before I close it on February 1.

The address is - The email address is This email address is being protected from spambots. You need JavaScript enabled to view it..

Note that most images will be still posted on NZ Astronomers, but the NZ- Astrophoto discussion group is for those who don't want the wider community to see their images, or want to discuss something technical, etc...

-- John Drummond

9. Implications of Earth Observation in New Zealand

"What on Earth: An International Colloquium Exploring Science & Policy Implications of Earth Observation in New Zealand" - Thursday 17 February 2011, Wellington

The Royal Society of New Zealand, in collaboration with the European Space Agency and Venture Southland, is hosting an international event exploring the opportunities for using satellite imagery and improved data and image access. Presentations will be given by organisations including: European Space Agency, German Space Agency, Italian Space Agency, Swedish Space Corporation and Telespazio.

The event is free to attend, with further details of the programme and registration available at: earth/

-- from Royal Society of New Zealand Alert - Issue 652, today.

10. Royal Society of NZ Award Applications Sought

The Royal Society of New Zealand is calling for applications for the following awards:

  • Charles Fleming Fund - Travel Award
  • Charles Fleming Fund - Senior Scientist Award
  • Charles Fleming Fund - Publishing Award

The closing date for applications is 31 March 2011.

Information on these awards, and application forms are available on the Society´s website:

All applications will be acknowledged via email, within a fortnight of receipt of the applications.

Judy Lyons Executive Assistant, Academy, Corporate Affairs

11. RASNZ Conference 2011

A further reminder that this year's RASNZ Conference is being held in Napier on 27-29 May 2011. The venue is the Napier War Memorial Convention Centre on the north end of Marine Parade. Conference registration forms were sent out with the December issue of Southern Stars, and are also available on the RASNZ Webpage - see There is a wide range of accommodation within easy walking distance of the venue. This ranges from backpackers through to top-notch hotel accommodation. Some suggestions are available by referring to:

Although Conference itself will run from the Friday evening till sometime on the Sunday afternoon, many of you will also want to make time for the other two events. Namely, the Fifth Trans-Tasman Symposium on Occultations which will be held on the Thursday, and into Friday morning, and the Photographic Workshop with David Malin to be held on the Monday following Conference. Graham Blow and John Drummond respectively will provide further information on these in due course.

But back to Conference itself. The Invited Speakers are well known to many of you. Dr David Malin has visited NZ several times in the past, most recently to Stardate South Island in January 2010. David's career has largely been with the Anglo-Australian Observatory (now the Australian Astronomical Observatory). He is also Adjunct Professor of Scientific Photography at RMIT University in Melbourne. David has authored many books on astrophotography, and his images are widely known. As well as presenting a feature paper, David will also be actively involved in the Imaging and Photographic Workshop.

The other Invited Speaker is Dr Fred Watson. Fred is an Englishman by
birth, but has lived in Australia for over 25 years. Fred is Astronomer-
In-Charge of the Australian Astronomical Observatory, and is Project
Leader for the Radial Velocity Experiment. In addition, Fred has been
active in promoting astronomy to the public through, publications, talks
and, more recently overseas tours and theatre shows. In addition to his
feature paper, Fred will be delivering a public lecture later on the
Sunday afternoon following the formal conclusion of Conference.  We look
forward to hearing from these two renowned and respected astronomers. The
titles of their talks will be listed on the RASNZ Webpage in due course.

The Standing Conference Committee is now calling for papers. We invite members and prospective attendees to consider giving a paper and/or poster-paper, and expressions of interests can be made with the Standing Conference Committee - please email: This email address is being protected from spambots. You need JavaScript enabled to view it.. Or better still - please go to the RASNZ Webpage (, and complete and email back the appropriate form for consideration by the Committee. We are please to have received a number of applications to present papers already. There is a final deadline of 1 April when final titles and abstracts need to be submitted, but if you wish to present a paper then please complete the submission form as soon as possible so that we can give it early consideration.

We hope to see many of you at Conference. Good travel discounts are still available for those using public transport. But it would pay to make early bookings.

We also wish to acknowledge Matariki Wines, Holt Planetarium, WASP, Easy
Print, Graham Palmer Photography and Astronomy Adventures as sponsors to
date of the 2011 RASNZ Conference. Also the contributions from the Hawkes
Bay Astronomical Society and the RASNZ Conference Fund are acknowledged.

As with any Conference of the nature of ours, costs are skyrocketing, GST has increased and we have no control over these added costs. So every little bit of sponsorship helps. Having researched the costs of some other conferences attended by primarily amateurs in their fields, I can say without doubt that the RASNZ Conference delivers outstanding value for money.

Further information about Conference is available on the RASNZ Webpage

-- Dennis Goodman, Chair, RASNZ Standing Conference Committee.

12. Odyssey Orbiter Passes Martian Longevity Record

NASA's Mars Odyssey orbiter has worked longer at Mars than any other spacecraft in history. Odyssey entered orbit around Mars on Oct. 24, 2001. On December 15, the 3,340th day since that arrival, it passed the Martian career longevity record set by its predecessor, Mars Global Surveyor, which operated in orbit from 11 September 1997, to 2 November 2006.

Odyssey made its most famous discovery -- evidence for copious water ice just below the dry surface of Mars -- during its first few months. It finished its radiation-safety check for future astronauts before the end of its prime mission in 2004. The bonus years of extended missions since then have enabled many accomplishments that would not have been possible otherwise.

The extra years have allowed high-resolution mapping of virtually the entire planet. The maps are assemblages of images from the orbiter's Thermal Emission Imaging System (THEMIS) camera. To mark the approach to the Mars longevity record, the camera team and NASA prepared a slide show of remarkable images,posted at

The orbiter's longevity has given Odyssey scientists the opportunity to monitor seasonal changes on Mars year-to-year, such as the cycle of carbon-dioxide freezing out of the atmosphere in polar regions during each hemisphere's winter.

Odyssey's performance has benefited other missions, too. When NASA's Mars Exploration Rovers, Spirit and Opportunity, far exceeded their own expected lifetimes, Odyssey remained available as the rover's primary communication relay. Nearly all the science data from the rovers and NASA's Phoenix Mars Lander has reached Earth via Odyssey relay. Odyssey also became the middle segment of continuous observation of Martian weather by a series of NASA orbiters: Mars Global Surveyor, Odyssey, and NASA's Mars Reconnaissance Orbiter, which began its science mission in late 2006.

Odyssey's detection of hydrogen just below the surface of Mars throughout the planet's high-latitude regions indicated water there. That prompted the Phoenix mission, which confirmed that fact in 2008.

For more about the Mars Odyssey mission, visit:

-- from a NASA Jet Propulsion Laboratory press release forwarded by Karen Pollard.

13. Metals in the Mantle Tell How Planets Formed

New research reveals why we find so-called highly siderophile, or metal- loving, elements like gold and platinum in the mantles of Earth, the Moon and Mars. They were delivered by massive impactors during the final phase of planet formation over 4.5 billion years ago. The predicted sizes of the projectiles are consistent with current planet formation models. All hit within tens of millions of years of the giant impact that produced our Moon.

The sizes are also consistent with physical evidence such as the size distributions of asteroids and ancient Martian impact scars. They predict that the largest of the late impactors on Earth were 2000 to 3000 km in diameter. They could have changed the tilt of Earth's axis by 10 degrees. The moon impactors were 250-300 km in diameter and may have delivered water to its mantle.

The team that conducted this study comprised solar system dynamicists and geophysical-geochemical modellers. Together, they represent three teams within the NASA Lunar Science Institute (NLSI).

A fundamental problem in planetary science is to determine how Earth, the Moon, and other inner solar system planets formed and evolved. This is a difficult question to answer given that billions of years of history have steadily erased evidence for these early events. Despite this, critical clues can still be found to help determine what happened, provided one knows where to look.

For instance, careful study of lunar samples brought back by the Apollo astronauts, combined with numerical modelling work, indicates that the Moon formed as a result of a collision between a Mars-sized body and the early Earth about 4.5 billion years ago. The idea that the Earth-Moon system owes its existence to a single, random event was initially viewed as radical. It is now believed that such large impacts were commonplace during the end stages of planet formation. The giant impact is believed to have led to a final phase of core formation and global magma oceans on both the Earth and Moon.

For the giant impact hypothesis to be correct, one might expect samples from the Earth and Moon's mantle, brought to the surface by volcanic activity, to back it up. In particular, scientists have examined the abundance in these rocks of so-called highly siderophile, or metal-loving, elements: rhenium, osmium, iridium, ruthenium, platinum, rhodium, palladium and gold. These elements should have followed the iron and other metals to the core in the aftermath of the Moon-forming event, leaving the rocky crusts and mantles of these bodies void of these elements. Accordingly, their near-absence from mantle rocks should provide a key test of the giant impact model. However the big problem for the modellers is that these metals are not missing at all, but instead are modestly plentiful.

A proposed solution to this conundrum is that highly siderophile elements were indeed stripped from the mantle by the effects of the giant impact. However, they were then partially replenished by later impacts from planetesimals, the original building blocks of the planets. This is not a surprise -- planet formation models predict such late impacts -- but their nature, numbers, and most especially size of the accreting bodies are unknown. Presumably, they could have represented the accretion of many small bodies or a few large events. To match observations, the late- arriving planetesimals need to deliver 0.5 percent of the Earth's mass to Earth's mantle,equivalent to one-third of the mass of the Moon, and about 1,200 times less mass to the Moon's mantle.

Using numerical models, the team showed that they could reproduce these amounts if the late accretion population was dominated by massive projectiles. Their results indicate the largest Earth impactor was 2500 to 3000 km in diameter, roughly the size of Pluto, while those hitting the Moon were only 250 to 300 km across.

Impactors of these sizes are thought to be large enough to produce the observed enrichments in highly siderophile elements, but not so large that their fragmented cores joined with the planet's core. They probably represent the largest objects to hit those worlds since the giant impact that formed our Moon.

Intriguingly, the predicted distribution of projectile sizes, where most of the mass of the population is found among the largest objects, is consistent with other evidence.

* New models describing how planetesimals form and evolve suggest the biggest ones efficiently gobble up the smaller ones and run away in terms of size, leaving behind a population of enormous objects largely resistant to collisional erosion.

* The last surviving planetesimal populations in the inner solar system are the asteroids. In the inner asteroid belt, the asteroids Ceres, Pallas and Vesta, at 1000, 500 and 500 km across respectively, dwarf the next largest asteroids at 150 miles across. No asteroids with "in-between" sizes are observed in this region.

* The oldest and largest craters on Mars are many thousands of km across. This is consistent with Mars being bombarded by an inner asteroid belt- like population dominated by large bodies early in its history.

These results make it possible to make some interesting predictions about the evolution of the Earth, Mars and the Moon. For example:

* The largest projectiles that struck Earth were capable of modifying its spin axis, on average, by approximately 10 degrees.

* The largest impactor to strike Mars was 1400 to 1800 kms across, according to this work and the abundance of highly siderophile elements found in Martian meteorites. This is approximately the size needed to create the proposed Borealis basin that may have made the difference between Mars's two hemispheres.

* For the Moon, the projectiles would have been large enough to have created the South-Pole-Aitkin basin or perhaps a comparable-sized early basin. Moreover, if they contained even a trace amount of volatiles, then the same processes that brought highly siderophile elements to the Moon's mantle may have also delivered its observed abundance of water.

The article, "Stochastic Late Accretion to the Earth, Moon, and Mars" was published in the December 10 issue of Science.

-- From a press release by the Southwest Research Institute in San Antonio, Texas forwarded by Karen Pollard.

14. Cepheid Mass Measured

Classical Cepheid variables, usually called just Cepheids, are unstable stars that are larger and much brighter than the Sun. They expand and contract in a regular way, taking anything from a few days to months to complete the cycle. The time taken to brighten and fade is longer for luminous Cepheids than for dimmer ones. This remarkably precise relationship makes the study of Cepheids one of the most effective ways to measure the distances to nearby galaxies. These measures then give the scale of the whole Universe.

Unfortunately, despite their importance, Cepheids are not fully understood. Predictions of their masses derived from the theory of pulsating stars are 20-30% less than predictions from the theory of the evolution of stars. This embarrassing discrepancy has been known since the 1960s.

To resolve this mystery, astronomers needed to find a double star containing a Cepheid where the orbit happened to be seen edge-on from Earth. In these systems, known as eclipsing binaries, the brightness of the combined light dims as one star passes in front of the other. It dims again when the positions are reversed. In such pairs astronomers can determine the masses of the stars to high accuracy. Unfortunately neither Cepheids nor eclipsing binaries are common, so the chance of finding such an unusual pair is very low. None are known in the Milky Way.

Fortunately such a system has been found in the Large Magellanic Cloud. Known as OGLE-LMC-CEP0227, it contains a Cepheid variable star pulsating every 3.8 days. The other star is slightly bigger and cooler. The two stars orbit each other in 310 days. By using the HARPS spectrograph on the 3.6-meter telescope at the European Southern Observatory's La Silla Observatory in Chile along with other telescopes, astronomers have measured the mass of the Cepheid to about 1%. The mass agrees exactly with predictions from the theory of stellar pulsation. However, the larger mass predicted by stellar evolution theory was shown to be significantly in error.

The much-improved mass estimate is only one outcome of this work. The team hopes to find other examples of these remarkably useful pairs of stars to exploit the method further. They also believe that from such binary systems they will eventually be able to pin down the distance to the Large Magellanic Cloud to 1%, which would mean an extremely important improvement of the cosmic distance scale.

The results appeared in the 25 November 2010 edition of Nature.

-- from a European Southern Observatory press release forwarded by Karen Pollard

15. Gifford-Eiby Lecture Fund

The RASNZ administers the Gifford-Eiby Memorial Lectureship Fund to assist Affiliated Societies with travel costs of getting a lecturer or instructor to their meetings. Details are in RASNZ By-Laws Section H.

For an application form contact the Executive Secretary This email address is being protected from spambots. You need JavaScript enabled to view it., P.O. Box 3181, Wellington.

16. Kingdon-Tomlinson Fund

The RASNZ is responsible for recommending to the trustees of the Kingdon Tomlinson Fund that grants be made for astronomical projects. The grants may be to any person or persons, or organisations, requiring funding for any projects or ventures that promote the progress of astronomy in New Zealand. Full details are set down in the RASNZ By-Laws, Section J.

For an application form contact the RASNZ Executive Secretary, This email address is being protected from spambots. You need JavaScript enabled to view it., P.O. Box 3181, Wellington.

17. How to Join the RASNZ

A membership application form and details can be found on the RASNZ website Please note that the weblink to membership forms is case sensitive. Alternatively please send an email to the membership secretary This email address is being protected from spambots. You need JavaScript enabled to view it. for further information.

The annual subscription rate is $75. For overseas rates please check with the membership secretary, This email address is being protected from spambots. You need JavaScript enabled to view it..

18. Here and There

From The Observatory, v. 130, No. 1219, 2010 December.

COLOUR BLIND ...a red dwarf... is so densely packed with matter that a cubic inch would weigh more than 10 tons! -- Daily Telegraph, February Night Sky.

HARDLY SURPRISING Spica, if seen from close up, would be one of the super-bright stars. -- Daily Telegraph, March Night Sky.

THIRSTY WORK, ASTRONOMY Following Sir Arnold's talk there was a welcome break for coffee. -- SHA Bulletin, 2009 June, p.24.

Alan Gilmore Phone: 03 680 6000 P.O. Box 57 This email address is being protected from spambots. You need JavaScript enabled to view it. Lake Tekapo 7945 New Zealand

Newsletter editor:

Alan Gilmore   Phone: 03 680 6000
P.O. Box 57   Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Lake Tekapo 7945
New Zealand