< Radiation astronomy
This is a visual image of NGC 2788A near the edge of the constellation Volans. Credit: Aladin at SIMBAD.

The first neutron source in Volans is unknown.

The field of neutron astronomy is the result of observations and theories about neutron sources detected in the sky above.

The first astronomical neutron source discovered may have been the Sun.

But, neutrons from the Sun are intermingled with other radiation so that the Sun may appear as other than a primary source for neutrons.

The early use of sounding rockets and balloons to carry neutron detectors high enough may have detected neutrons from the Sun as early as the 1940s.

This is a lesson in map reading, coordinate matching, and researching. It is also a research project in the history of neutron astronomy looking for the first astronomical neutron source discovered in the constellation of Volans.

Nearly all the background you need to participate and learn by doing you've probably already been introduced to at a secondary level and perhaps even a primary education level.

Some of the material and information is at the college or university level, and as you progress in finding neutron sources, you'll run into concepts and experimental tests that are actual research.

First step

The first step is to succeed in finding a neutron source in Volans.

Next, you'll need to determine the time stamp of its discovery and compare it with any that have already been discovered.

Over the history of neutron astronomy a number of sources have been found, many as point sources in the night sky. These points are located on the celestial sphere using coordinate systems. Familiarity with these coordinate systems is not a prerequisite. Here the challenge is geometrical, astrophysical, and historical. The coordinates are usually supplied by the neutron source observers.

Neutron sources

Def. a natural source usually of radiation in the sky especially at night is called an astronomical source.

A source of astronomical information on older detections of neutron sources is included in the Science section of the lecture/article neutron astronomy.

Traveling neutron sources

Many neutron sources do not remain in a constellation for lengthy periods. Some of these are the Sun and sources apparently in orbit around the Sun. The Sun travels through the 13 constellations along the ecliptic (the plane of the Earth's orbit around the Sun): the 12 of the Zodiac and the constellation Ophiuchus. These are described in source astronomy.

Backgrounds

To introduce yourself to some aspects of the challenge may I suggest reading the highlighted links mentioned above, and if you're curious, those listed under the section See also below.

Neutrons are a form of radiation that is currently part of subatomic particle radiation intersecting the Earth. More information about radiation is in radiation astronomy.

Constellations

This is an image of the International Astronomical Union (IAU) sky map of the constellation Volans. Credit: IAU and Sky & Telescope magazine (Roger Sinnott & Rick Fienberg).

The Wikipedia article about the constellation Volans contains a high school level description. The figure at right shows the sky map of Volans. Around the edges of the map are coordinates related to longitude and latitude, but with the Earth rotating on its axis every 24 hours the celestial coordinates must remain fixed relative to the background light sources in the sky.

Volans is one of the 12 constellations that were introduced by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman in the late 16th century. It was first depicted on Petrus Plancius’ globe in 1598. Plancius called the constellation Vliegendenvis (flying fish).[1]

Also, in the Wikipedia article is a list of stars in Volans.

Searching catalogs

In the lecture/article neutron astronomy in its science section is a list of older catalogs of neutron sources. Using the constellation description in the previous section and the range of coordinates for the constellation in source astronomy, scan through the coordinates for these neutron sources to see if any may be within Volans.

If you find any that are, skip down to the section Neutron sources in Volans and make an entry. Be sure to check the coordinate era, most B1950 coordinates have changed slightly to the new J2000 set. Try the catalog designation at either SIMBAD website.

Testing a source

There are many web sites that may have an neutron source listed for the constellation Volans. Some that you may wish to try are in the External links section near the bottom of this lesson.

Wikipedia sources

A. Constellation article

Under "Notable features" in the Wikipedia article on the constellation Volans is the list of stars in Volans. Click on this link. In the table of this Wikipedia article is α Vol. To the right are coordinates:

Right ascension (RA): 09h 02m 26.79592s and Declination (Dec): -66° 23' 45.8727".

Find these coordinates on the Volans map at the right.

To evaluate the star as a neutron source, skip ahead to section "Neutron sources".

B. Wikipedia search

Another way to look for neutron sources in the constellation is to perform a search on Wikipedia. Try "Volans neutron" without the quotes. This yields only 2 returns which include an outline of astronomy and a Sun computer.

The outline of astronomy names no neutron sources.

SIMBAD sources

Another way to find possible neutron sources in Volans is to use search queries on SIMBAD.

Click on either SIMBAD link under "External links" below, then click on "Criteria query", or "by criteria".

In the tan box, type in "region(09 02 26.79592 -66 23 45.8727,10m)", without the quotes. This tells the SIMBAD computer you are interested in a circular region of the celestial sphere centered on the coordinates for alpha Volantis, with a radius of 10 arcminutes (m), or try 10d for 10 degrees.

Notice on the page over at the right from the tan colored box: "Return". The default is "object count". Click on "submit query". In a few moments a result something like "Number of objects: 9" should appear. Click "Back" to see the tan box again.

Adding an object type such as & otype='IR' to the region request reduces the returned number to those that are infrared sources. But, all of the otypes listed at Object classification in SIMBAD contain only neutron stars, not neutron sources.

The SIMBAD criteria search allows you to specify spectral types for possible stars. The criteria "sptype" (the exact spectral type): returns only the objects having the requested spectral type (i.e. sptype = 'k0' does not return 'K0III',...). And, "sptypes" should be used to retrive all objects having a spectral type containing the one specified; i.e., sptypes = 'K0' will return all objects having 'K0' as a spectral type, but also 'K0III' or 'K0IIIp', ...).

But, here again no information about possible neutron sources is listed.

If a flare star is a likely source of neutrons, then entering otype='Fl*' should locate neutron sources.

Using only otype='Fl*' on SIMBAD yields 2582 in all of SIMBAD.

SAO/NASA Astrophysics Data System

In the naming of sources per constellation, the genitive is in common use. For Volans, the genitive is Volantis.

Click on the SAO/NASA Astrophysics Data System link below in the "External links". Try "Volantis neutron" without the quotes, or "alpha volantis" with quotes, followed by neutron.

Click on a link below # Bibcode Authors. If the Abstract describes the detection of neutrons from a source in the constellation Volans, go to the next section under "SAO/NASA Astrophysics Data System".

If it does not try another bibcode link.

Evaluating neutron sources

There are several ways to evaluate a neutron source for the constellation Volans.

Wikipedia sources

Click on the link to the Wikipedia article. After you've enjoyed reading about the source, use the 'find' command of your browser to see if this Wikipedia page mentions anything about neutrons. Does the article mention whether or not the source is a neutron source?

What is the current time stamp for the Wikipedia article on the source? [Hint]: look for something like "This page was last modified on 25 December 2011 at 20:12." very near the bottom of the page. For now this is an adequate time stamp.

From reading the Wikipedia article on the source, if you believe the text demonstrates that the source is not a neutron source in Volans edit the "Non-neutron sources in Volans" section near the bottom of the page with an entry similar to "# Alpha Volantis 25 December 2011 at 20:12 Wikipedia article "Alpha Volantis", without the quotes, and finish the entry with four "~"s without the quotes after the period. The date included with your designation or username is a time stamp for the entry. The last portion of the entry is the source of your information.

On the other hand, if there are one or more sentences in the article that you believe demonstrates that the source is a neutron source in Volans edit the section below "Neutron sources in Volans" with a similar entry.

Go to the section entitled, "Challenging an entry".

The Wikipedia article on Alpha Volantis mentions: Alpha Volantis is an Am star, 'm' for metal lines, with a stellar classification of kA3hA5mA5 V[2]

From the lecture/article on neutron astronomy, the neutron radiation band may not have a wavelength temperature pair.

Is the primary star of alpha Volantis a neutron star, or a neutron source?

Wikimedia commons

Another possible website for neutron sources is Wikimedia Commons, url=https://commons.wikimedia.org/wiki/Main_Page. Try entering "neutron Volans".

This returns no images of any neutron sources in Volans.

SIMBAD sources

To check any source (even one from Wikipedia) on SIMBAD, click of the "External link" to the "SIMBAD Astronomical Database".

At the lower right side of the SIMBAD Astronomical Database page is a "Basic search" box. There are several ways to try your target:

  1. source name: without the quotes or
  2. source coordinates: without the quotes, for example, "12 26 35.94 -63 05 56.6".

If you are looking at a SIMBAD generated table which lists possible targets, click on one.

Having SIMBAD list all of its 2582 flare stars produces an apparently formidable task. Try searching with your browser using "Vol". While using "Mon" for Monoceros locates 45 in the lost, "Vol" finds none.

Many of the flare stars listed do not include a constellation designation. Letting SIMBAD plot all of these flare stars and comparing the plot with the constellation sky chart shows that no flare stars listed in SIMBAD occur within the right ascension and declination ranges of Volans.

Another possibility is to use otype='X' for X-ray sources or otype='gam' or otype='gB' for gamma-ray sources. Either of these may indicate a neutron source.

There are 3509 otype='gam' listed in SIMBAD. Plotting them may be helpful or scanning them using either -6 or -7 with your browser will eventually reveal six gamma-ray sources that may also be neutron sources, such as AGN AT20G J081103-75302.

If you have already found a neutron source (or a table of them) using SIMBAD, click on the blue link identifier for the first.

SIMBAD time stamp

Peruse the SIMBAD page for a time stamp or date of last revision. [Hint: it may look something like "2012.01.09CET20:10:02" and be in the upper right.]

If the entry at SIMBAD convinces you that the source is not a neutron source, edit the "Non-neutron sources in Volans" section near the bottom of this page and type in an entry similar to "# Source Name 2012.01.09CET20:10:02 SIMBAD article "SIMBAD source name".", without the first set of quotes, followed by four ~s.

If your SIMBAD analysis convinces you that you have found a neutron source in Volans (did you check the coordinates vs. the map of Volans?), make an entry something like the ones in the section "Neutron sources in Volans".

SAO/NASA Astrophysics Data System sources

If the abstract states that an neutron source in Volans is detected or studied, consider entering it in the section "Neutron sources in Volans" below.

Abstract time stamp

On the abstract page is a Publication Date:. This may serve as a time stamp for establishing that the source is detected as a neutron source on or before the date of publication. The time stamp followed by four ~s for your verification as determiner in the section "Neutron sources in Volans" completes your entry.

Challenging an entry

Any entry in either the section "Neutron sources in Volans" or "Non-neutron sources in Volans" can be challenged. The time stamp can be challenged to see if there is an earlier one. The source can be challenged by an earlier source.

Wikipedia challenges

Is Wikipedia a 'primary source', or does the Wikipedia article cite a source?

Even though Wikipedia has an article on the source, is it a good place to stop in testing whether the source has been detected as an astronomical neutron source?

If the Wikipedia article cites a primary source, skip down to the section on "Primary sources".

SIMBAD challenges

Is SIMBAD a 'primary source'?

SIMBAD is an astronomical database provided by the Centre de Données astronomiques de Strasbourg. It is an authoritative source, but they do occasionally make a mistake.

If you find a neutron source within the constellation on SIMBAD, the next step is to find the earliest time stamp of discovery.

SAO/NASA Astrophysics Data System challenge

Is the SAO/NASA Astrophysics Data System abstract entry a primary source?

The SAO/NASA Astrophysics Data System is an astronomical database provided by the High Energy Astrophysics Division at the Harvard-Smithsonian Center for Astrophysics of Harvard University. The abstract has been copied from the actual article in a scientific journal or other publication. Mistakes can be made and the article may record within its text exact dates when the observation or detection of neutrons actually occurred. Such a record may provide an earlier time stamp.

Primary sources

Primary sources may be searched for possible additional information perhaps not yet evaluated by SIMBAD or not presented in a Wikipedia article about a source.

Wikipedia test sources

For a Wikipedia article that cites a primary source, scroll down to the reference and open the reference. Read through the article looking for where the source mentioned in the Wikipedia article occurs. Some primary source authors may use source designations that are not mentioned in the Wikipedia article. To look for other designations, click on the link to SIMBAD in the "External links" on this page, enter the source name from the Wikipedia article, and see if other names are mentioned in the article.

When none of the names are mentioned, click on the link for "Google Advanced Search" in the list of "External links", enter the source name or designation(s) such as "Gliese 866", with neutrons to see if the source has a reference indicating it is a neutron source. And, look for the earliest one. Compose an entry using the primary source.

SIMBAD test sources

Further down the SIMBAD page is a list of "Identifiers". Click on the blue bold portion.

On the page that appears should be a primary source listed after Ref:. Click on the blue link with the oldest year. This yields an earlier time stamp and entry citation like the current one in the section "Neutron sources in Volans". If you find another source or an earlier time stamp, compose a similar entry and edit the section. Additional information to add into the reference can be found by clicking on "ADS services" from the SIMBAD page.

SAO/NASA Astrophysics Data System sources test

Click on either the "Electronic Refereed Journal Article (HTML)" or "Full Refereed Journal Article (PDF/Postscript)", if available.

Depending on the article display, if the abstract is repeated and the article is listed as FREE, click on either the PDF or HTML version.

While scanning or reading the article look for "Observations" (or use the Find function of your browser) and the possible inclusion of dates for these. If more than one neutron source in Volans are detected, which one(s) would you list in the section "Neutron sources in Volans" below?

An example of an article reference is provided in that section.

Changing an entry

From your analysis of the source so far, is it a neutron source?

If you have found an earlier time stamp for the source than the one listed in the section below "Non-neutron sources in Volans" and the answer to the above question is "no", you can edit the section with your result. Or, you can leave the entries as is and try another star.

If you have found an earlier time stamp for the source than the one listed in the section below "Neutron sources in Volans", edit the section with your result. Or, if you found another neutron source with a comparable or earlier time stamp, edit the section with your result.

Neutron sources in Volans

  1. 1FGL J0849.0-6754 SIMBAD: "C.D.S. - SIMBAD4 rel 1.218 - 2014.02.02CET06:35:51", "otype='gam'", found by searching the list of gamma-ray sources using "-6". --Marshallsumter (discuss • contribs) 05:44, 2 February 2014 (UTC)

Non-neutron sources in Volans

Oldest records

SIMBAD annotations

For any particular source, the SIMBAD record may indicate that it is not a neutron source yet above you may have found at least two refereed journal articles to indicate that it is. Use the second SIMBAD External links to directly display the SIMBAD database in France.

Enter the name source you have found into the search box. Scroll down to the Annotations :. Look for the link "add an annotation to this object". With browser open to the literature citations available, click on this link. You may need to register as a user. It's free. Post your annotation containing the literature references.

Hypotheses

  1. Neutron sources may be quite common.

The "possibility has been discussed by various authors that solar neutrons and 2.2-MeV gamma rays are produced by the nuclear interactions of flare-accelerated particles with solar material."[3]

The "ratio of neutrons to 2.2-MeV gamma rays depends significantly on the direction of motion of the flare-accelerated particles with respect to the solar atmosphere. For the direction of motion of flare-accelerated particles, we shall consider three cases: (a) isotropic motion, (b) upward-directed motion towards the corona, (c) downward-directed motion towards the photosphere. These flare-accelerated particles would interact with the solar atmosphere to produce neutrons with energies above several MeV. Some of the neutrons will escape into space through the corona, while some will be slowed down in the denser atmosphere and captured by the atmospheric protons with the emission of 2.2-MeV gamma rays."[3]

The "ratio of neutrons to 2.2-MeV gamma rays for case (b) is 10–20 times that for (a) or (c). The value for case (c) is twice that for case (a). For the expected solar neutron intensity, the values for (b) and (c) are ~10−6 and 4 × 10−2 of that for (a), respectively."[3]

If stellar flares have origins similar to solar flares, then flare stars produce neutrons. Only relativistic neutrons would be able to reach Earth before decaying.

See also

References

  1. ↑ Constellations: A Guide to the Night Sky. 2013.
  2. ↑ R. O. Gray, C. J. Corbally, R. F. Garrison, M. T. McFadden, E. J. Bubar, C. E. McGahee, A. A. O'Donoghue, E. R. Knox (July 2006). "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal 132 (1): 161–70. doi:10.1086/504637.
  3. 1 2 3 K. Ito, H. Okazoe, M. Yoshimori (May 1968). "Production of neutrons and gamma rays by nuclear interactions in solar flares". Canadian Journal of Physics 46 (10): S780-3. doi:10.1139/p68-350. http://www.nrcresearchpress.com/doi/abs/10.1139/p68-350?journalCode=cjp#.Uu29ya79UmU. Retrieved 2014-02-01.

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