Nova Newsletter – Sept/Oct 2017

Our NOVA Newsletter, for Sept-Oct 2017 is available as a hi-res or low-res pdf file.   An archive of older issues can be found on our Newsletter page.

Contents of Volume 2017, Issue 5, September-October-2017:

  • The 2017 Total Eclipse from Madras, OR by Gordon Farrell
  • President’s Message by Suzanna Nagy
  • A Message from our Observing Chair by Robert Conrad
  • Aug 21 Eclipse Event at Science World by Suzanna Nagy
  • The Missed Perseids by J. Karl Miller
  • RASC’s National Star Party 2017: A Coast to Coast Event by Leigh Cummings

Image of Surface and Atmosphere on Antares

A team of astronomers, led by Keiichi Ohnaka, of the Universidad Católica del Norte in Chile, used the ESO’s Very Large Telescope Interferometer (VLTI) at the Paranal Observatory in Chile to capture an image of Antares that reveals surface details!  This is the best image of the surface and atmosphere of any star other than the Sun.

Antares Surface Details
Surface details on Antares appear in this image taken by the European Southern Observatory’s Very Large Telescope Interferometer. Credit: ESO/K. Ohnaka

Antares is a bright star in Scorpius that shines with a strong red tint.  It is a large red supergiant in the later stage of its life and is expected to become a supernova in a few thousand years.  It is located nearly 620 light-years from Earth with a mass and diameter  of 12 times and 700 times that of our sun, respectively.

The team also made the first map of the velocities of material in the atmosphere of a star, other than the Sun, revealing unexpected turbulence in Antares’s extended atmosphere. In stars like our sun, convection flows of superheated gases bubble up from near the stars’ cores to the surface. But convection cannot explain Antares’ strange atmosphere, and the researchers conclude that, for the atmospheres of red supergiants, there must be another—as yet unknown—process that drives the motion of material.  This process might help explain how stars like Antares lose mass so quickly in the final phase of their evolution.

Ohnaka is hopeful that the observational techniques demonstrated on Antares may be applied to other stars to see how their atmospheres are structured, perhaps revealing the mystery that drives these turbulent motions.

The VLTI consists of up to four telescopes—8.2 m “unit” telescopes and smaller 1.8m “auxiliary” telescopes – that combine light using interferometry to create a “virtual” telescope 200 m wide. Very high angular resolution can therefore be attained, allowing the surface of Antares to be studied in detail.

 

National Star Party to Celebrate Canada’s 150th Birthday

The Royal Astronomical Society of Canada is celebrating Canada’s 150th Birthday with a nation wide star party. RASC Vancouver is holding our event at Maple Ridge’s Selvey Park on Saturday, July 29th, 2017 starting at 08:30 pm.

Our members will have lots of telescopes and binoculars for you to look through, and do not hesitate to bring your own. This is a family friendly event and is free to everyone. Even in July it can get quite chilly at night so please bring clothing layers. Please apply any bug repellent while you are in the parking lot.

This is a weather dependant event and will be cancelled if overcast or raining.

Maple Ridge’s Selvey Park has a relatively dark sky and is less than an hour’s drive from downtown Vancouver.

The light pollution is minimal due to it being surrounded by farm land and people who value the rural life.  This allows viewing of magnitude 5 stars on a moonless night; for example, the dimmest stars in the “Little Dipper” are magnitude 5. If the conditions are good we should get to see a hint of the Milky Way.

The Moon will be 46% illuminated in the evening sky. It will be setting just after midnight so we should have some good deep sky viewing afterwards.

Vancouver 29th July 2017
View to the South from Maple Ridge on  July 29th,  2017 at 10:00 pm.

The planets Jupiter and Saturn will also be visible.

Partial Solar Eclipse – Aug 21st, 2017

The Moon will cover approximately 85% of the Sun in Vancouver during the Solar Eclipse on Monday, August 21st, 2017.  Please join us at Science World where RASC Vancouver will have solar telescopes, solar displays, and eclipse shades for everyone’s enjoyment and safe viewing.  Check out our meetup event or our eclipse page for more information.

 

Observing in Red and White

 

Canada Day 150 is less than one week away so it is good time to respect the colours of flag and do some solar observing in red and white light. At the Canada Day 150 celebrations in Maple Ridge, members of RASC will have telescopes, equipped with red and white filters, available for viewing of the Sun (weather permitting).

Warning: NEVER look directly at the Sun through binoculars, a telescope or with your unaided eye. Serious eye damage and even blindness can result!

High-quality solar filters that remove infrared and ultraviolet radiation and allow only a small fraction of the Sun’s visible light through are required to safely view the Sun. The most popular solar filters are a white light filter where the Sun appears white and a Hydrogen-alpha filter where the Sun appears red.

White Light Solar Filters

White light solar filters are very dark neutral density filters – they transmit only 0.001% of the light. These filters allow you to see sunspots on the surface of the sun and are ideal for viewing solar eclipses and transits of Mercury or Venus. Some granulation (texture) on the surface of the sun can also be seen. However, solar prominences can not be observed with a white light filter and require the use of a hydrogen-alpha filter. Filters made from Baader Astro Solar Film are popular, inexpensive, and high-quality.  Baader solar film is a thin material similar to Mylar that gives a pure white image.

Sun through a white light filter
Sunspots visible using a white light filter made with Baader solar film.  Taken with a cell phone through a Skywatcher ED100 refractor.  Image Credit:  Ken Jackson, May 2012.
Hydrogen-Alpha Solar Filters

Hydrogen-alpha (H-alpha) filters transmit only one specific wavelength of light: a deep red light that is emitted by the hydrogen atoms which make up the bulk of the sun.  Like white light filters, the overall light transmission is only 0.001% for safe observing, and potentially harmful infrared light is blocked completely.

H-alpha filters are much more expensive than white light filters. The least expensive ones; from companies like Lunt, Coronado, or DayStar; start at about $700.

Prominence visible using a Hydrogen-alpha filter.
Prominence visible in the deep red light from a Hydrogen-alpha filter in a Lunt 50mm solar scope.  Image credit:  Ken Jackson, June 25th, 2017

These companies also offer specialized solar scopes which are normally small refactors with an H-alpha filter already built-in. The sun is bright and does not require a large aperture telescope for viewing it in detail so most solar observers use 40-90mm diameter refractors.

White light filters provide an inexpensive way to start observing the Sun but H-alpha filters reveal its ferocious dynamics. Prominences, spicules, fibrils, and flares become visible. Prominences can be seen at the limb as brilliant blobs, as loops or as sprays. Structural changes can occur in as few as 10 minutes. They’re also capable of shooting higher up in the corona before the material recollects and falls back into the chromosphere.

Images taken through Hydrogen-alpha filters reveal details on the Sun’s surface and can be processed to create a yellow image that is expected by most people.

The Solar disk in Hydrogen-alpha
The Solar disk in Hydrogen-alpha using a Coronado PST. Image Credit: Lorenzo Mezzimi

 

UBC Physicists Propose Fluctuating Space-Time

UBC Physicists recently proposed fluctuating space-time in a theory for dark energy that unifies general relativity and quantum mechanics. PhD students Qingdi Wang and Zhen Zhu along with professor Bill Unruh published their research in Physical Review D  last week. You can also find out more by listening to an interview with Jaymie Matthews that aired on CBC Vancouver’s The Early Edition:

The work suggests that, at very small scales, the  universe is constantly fluctuating between expansion and contraction. The fluctuations almost cancel each other but a small net effect is responsible for the “dark energy” that is causing the universe to expand at an accelerating rate.

Previous models of dark energy using quantum mechanics and relativity were not compatible. Models using quantum mechanics theorized that dark energy must be incredibly dense, but relativity predicted that the universe would explode with such dense dark energy.  This new research resolves the incompatibility between the two models.

 

Nova Newsletter – May/June/Astronomy Day 2017

Our NOVA Newsletter, for May-June 2017 and Astronomy Day, is available as a hi-res or low-res pdf file.   An archive of older issues can be found on our Newsletter page.

Contents of Volume 2017, Issue 3, May-June-Astronomy Day:

  • I Stood in the Crater that Killed the Dinosaurs by Suzanna Nagy
  • President’s Message by Suzanna Nagy
  • Bringing Youth into Astronomy by Leigh Cummings
  • Start with Imaging the Solar System – It’s Easy by Ken Jackson
  • Jupiter  Motion by Milan B

Halifax Residents Revolt Over Light Pollution from LED Street Lights

One of the most inspiring sights is standing under a dark sky with the night sky ablaze with stars. Today, this inspiration is diminished by ever-increasing light pollution. Energy efficient LED street lights, being installed by cities across Canada, can make things worse. Further, as Halifax and other cities have discovered: the residents often hate LED street lights.

Comparison of lighting colours and intensity of the new LED streetlights (left) and the older high-pressure sodium vapor lamps

An episode of The Current on CBC radio documents a complaint from a resident of Halifax who said the whiteness of the light keeps her whole family up at night – even her cat, Coco. Other cities have faced similar complaints and more: LED street lights have been blamed for stealing the romance of Rome, ruining nighttime film production in Los Angeles, and disorienting salmon in the Sacramento River.

The American Medical Association’s (AMA) research concludes that LED street lights that are too blue or white can suppress melatonin, affect our sleep, and lead to obesity. Other studies indicate an increased risk for certain cancers.

LED lighting is an amazing technology, and while LED street lights are costly to install, the new lights promise to last for decades, be maintenance-free, and cost considerably less to operate.

Colour is a major obstacle for LED lighting. The most cost-effective LEDs emit a much bluer light than the sodium vapour lamps that are traditionally used. Blue-rich LED lights increases the amount of glare sensed by the human eye and also the amount of visible light pollution. This occurs because blue light scatters more through the atmosphere than red light.

The colour for lighting is measured by a unit of temperature known as kelvins. The higher the kelvins the whiter the light. Light with a temperature between 2,000 and 3,000 kelvins is a warm white that’s comfortable, like the older lights. Light from LEDs with a temperature over 5,000 is extremely harsh: they’ve been called “zombie lamps” in Seattle and “prison lamps” in Oceanside, California.

Hopefully, cities in Canada and elsewhere will follow the AMA’s guidance on LED street lighting that includes several recommendations to help reduce light pollution.

  • The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light (less than 3000 kelvins).
  • The AMA also recommends all LED lighting should be properly shielded to minimize glare.
  • Consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.

For more information: