Radiation astronomy/First X-ray source in Andromeda

The first X-ray source in Andromeda is not known. This lesson is also a research project that needs your help. And, in exchange you'll be free to learn about star maps, astronomy, and the speciality of X-ray astronomy. The first such source in the constellation Andromeda is an astronomical X-ray source detected at some point in human history between now and a distant time mark in the past. It is an astronomical X-ray source detected in the constellation Andromeda.

This is an X-ray image of the Andromeda galaxy. Credit: ESA/XMM-Newton/EPIC/W. Pietsch.{{fairuse}}

This learning resource is experimental in nature because each learner interested in seeking this first X-ray source may start with any source and attempt to determine if this source is in Andromeda and is an X-ray source. Each currently known source has a history that includes earlier and earlier detections. To succeed, the adventurer need only show that their source has an earlier detection date as an X-ray source than previous adventurers.

The celestial sphere has coordinate systems often used to place a point source in the heavens. Familiarity with these coordinate systems is not a prerequisite. An introductory geography or map reading course or some familiarity with following a map is all that's needed.

Over the history of X-ray astronomy a number of astronomical X-ray sources have been discovered and studied, usually because they have something special about them that intrigues the researcher. The challenge of this resource is geometrical, astrophysical, and historical. As the ultimate answer is unknown, this is actually a research project, yet you may succeed!

Enjoy learning by doing!

First stepEdit

The first step is to succeed in finding an X-ray source in Andromeda.

Over the history of X-ray 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 X-ray source observers.

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

Traveling X-ray sourcesEdit

This image shows the Sun as viewed by the Soft X-Ray Telescope (SXT) onboard the orbiting Yohkoh satellite. Credit: NASA Goddard Laboratory for Atmospheres.

Many X-ray 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. Is Andromeda one of the constellations of the Zodiac?


To introduce yourself to aspects of the subject may I suggest reading the following resources: the first astronomical X-ray source and as mentioned above X-ray astronomy. Additional information may be found in astronomy, especially about fixing a point in the sky. X-rays are a form of radiation that is currently part of the electromagnetic radiation intersecting the Earth. More information about radiation is in radiation astronomy.


This is an image of the International Astronomical Union (IAU) sky map of the constellation Andromeda. Credit: IAU and Roger Sinnott & Rick Fienberg, Sky & Telescope magazine.
Johannes Hevelius's depiction of Andromeda is from the 1690 edition of his Uranographia. As was conventional for celestial atlases of the time, the constellation is a mirror image of modern maps as it was drawn from a perspective outside the celestial sphere. Credit: .
Andromeda as depicted in Urania's Mirror, a set of constellation cards published in London c. 1825, showing the constellation from the inside of the celestial sphere. Credit: .

The Wikipedia article about the constellation Andromeda contains a high school level description. The figure at right shows the sky map of Andromeda. 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. How has this been accomplished?

Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy. The uranography of Andromeda has its roots most firmly in the Greek tradition.

In Chinese astronomy, the stars that make up Andromeda were members of four different constellations that had astrological and mythological significance. In traditional Chinese astronomy, nine stars from Andromeda (including Beta Andromedae, Mu Andromedae, and Nu Andromedae), along with seven stars from Pisces, formed an elliptical constellation called "Legs".

A constellation related to Andromeda also exists in Hindu mythology.

A female figure in Andromeda's location had appeared earlier in Babylonian astronomy. The stars that make up Pisces and the middle portion of modern Andromeda formed a constellation representing a fertility goddess, sometimes named as Anunitum or the Lady of the Heavens.

An Arab constellation called "al-Hut" (the fish) was composed of several stars in Andromeda, M31, and several stars in Pisces. [Nu Andromedae] ν And, [Mu Andromedae] μ And, [Beta Andromedae] β And, [Eta Andromedae] η And, [Zeta Andromedae] ζ And, [Epsilon Andromedae] ε And, [Delta Andromedae] δ And, [Pi Andromedae] π And, and [32 Andromedae] 32 And were all included from Andromeda; [Nu Piscium] ν Psc, [Phi Piscium] φ Psc, [Chi Piscium] χ Psc, and [Psi Piscium] ψ Psc were included from Pisces.

Andromeda is also associated with the Mesopotamian creation story of Tiamat, the goddess of Chaos. She bore many demons for her husband, Apsu, but eventually decided to destroy them in a war that ended when Marduk killed her. He used her body to create the constellations as markers of time for humans.

In the Marshall Islands, Andromeda, Cassiopeia, Triangulum, and Aries are incorporated into a constellation representing a porpoise. Andromeda's bright stars are mostly in the body of the porpoise; Cassiopeia represents its tail and Aries its head.

In the Tuamotu islands, Alpha Andromedae was called Takurua-e-te-tuki-hanga-ruki, meaning "Star of the wearisome toil"

Also, in the Wikipedia article is a list of stars in Andromeda. What's the difference between a star and an astronomical X-ray source?

Testing a sourceEdit

Here an example is used for the upcoming steps in the lesson.

Under "Notable features" in the Wikipedia article on Andromeda the constellation is the brightest star: Alpheratz. In the star box of the Wikipedia article alpha Andromedae, below the image of the star are coordinates:

  1. Right ascension: 00h 08m 23.2586s and
  2. Declination: +29° 05' 25.555".

Are these coordinates from the Julian year (J) epoch J2000.0 or the Besselian year (B) B1950.0?

To convert from Besselian coordinates to Julian, use the Universal coordinate converter in the 'External links' section at this lesson's page bottom.

Find these coordinates on the Andromeda map at the right. Is alpha Andromedae (Alpheratz) really inside the constellation?

X-ray sourcesEdit

In the Wikipedia article on Alpheratz, use the 'find' command of your browser to see if this Wikipedia page mentions anything about "X-ray", or "X-rays". Does the article mention whether or not Alpha Andromedae is an X-ray source?

What is the current time stamp for the Wikipedia article on Alpheratz?

If you believe this proves that Alpha Andromedae is not an X-ray source in Andromeda edit the "Non-X-ray source in Andromeda" section near the bottom of the page with an entry similar to "# Alpheratz 14 December 2011 at 17:04 Wikipedia article "Alpha Andromedae"." and finish the entry with four "~"s without the quotes. The date included is a time stamp from the Wikipedia article. The last portion of the entry is the source of your information.

Is Wikipedia a 'primary source'?

Even though Wikipedia has an article on Alpheratz, is it a good place to stop in testing whether Alpha Andromedae has been detected as an astronomical X-ray source?

Provided under 'External links' at the bottom of this page is a number of helpful links. If your browser allows you to view a second window in parallel with this one, 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 use "Alpheratz", "alpha andromdae", or "Alpha Andromedae" or
  2. source coordinates: without the quotes "00 08 23.2586 +29 05 25.555".

The names take you directly to "V* alf And", but the coordinates yield a list, what's the difference between "V* alf And" in the table and "Alpha Andromedae" on Wikipedia?

If you are looking at the table which lists possible targets, click on the entry "V* alf And" to look at the entry.

On the page "V* alf And" read down the left side until you see "Other object types:". To the immediate right of this is a list of other object types that Alpheratz is. Look for an X. Is there one in this horizontal list?

In first astronomical X-ray source is a figure which shows the "X-rays" portion of "The Electromagnetic Spectrum". Do X-rays overlap with either "Gamma rays" or "UV"?

Look through the SIMBAD list again to see if either "gamma", "gam", "gB" for gamma-ray burst, or UV, EUV, or XUV occur. Do one or more occur?

There is a time stamp near the upper right on the SIMBAD page that looks like "2012.01.04CET18:42:34"

If the entry at SIMBAD convinces you that Alpheratz is an X-ray source, edit in an entry something like "# Alpheratz 2012.01.04CET18:42:34 SIMBAD article "V* alf And"." followed by four ~s in the section "X-ray source in Andromeda".

Challenging an entryEdit

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.

Let's say the source you've evaluated does not have an 'X' in the 'Other object types:' list at SIMBAD but it does have 'EUVE'. Is it really considered to be an X-ray source?

The graph in first astronomical X-ray source indicates that much of the high energy end of the ultraviolet is also called X-rays.

Entering "EUVE" without quotes into Wikipedia Search takes you to the article "Extreme Ultraviolet Explorer" wherein is "The Extreme Ultraviolet Explorer (EUVE) was a space telescope for ultraviolet (UV) astronomy, launched on June 7, 1992. With instruments for UV radiation between wavelengths of 7 and 76 nm, the EUVE was the first satellite mission especially for the short-wave ultraviolet range."

A browser search of this article with "X-ray" indicates that the article does not discuss X-rays. This suggests but does not confirm that "UV radiation between wavelengths of 7 and 76 nm" is not considered X-rays.

Together with UV in the 'Other object types:' list at SIMBAD may be the entry "UV(EUVE,TD1)". Entering TD1 into the Wikipedia search takes you to the disambiguation page with an entry "TD1 Catalog of Stellar Ultraviolet Fluxes, a star catalogue". This entry in turn has in its "References" section "TD1 - TD1 Stellar Ultraviolet Fluxes Catalog" at url=http://heasarc.gsfc.nasa.gov/W3Browse/td1/td1.html. From going to and reading this external link, are the wavelength ranges shorter or longer, higher or lower in energy than those of the Extreme Ultraviolet Explorer?

X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz (3×1016 Hz to 3×1019 Hz) and energies in the range 120 eV to 120 keV. X-rays from about 0.12 to 12 keV (10 to 0.10 nm wavelength) are classified as "soft" X-rays, and from about 12 to 120 keV (0.10 to 0.01 nm wavelength) as "hard" X-rays, due to their penetrating abilities.[1]

Is NASA a 'primary source'?

Primary sourcesEdit

From the SIMBAD entry for Alpheratz referring to TD1 (an ultraviolet observatory satellite) and the NASA secondary source, it seems that Alpheratz either is not an X-ray source or has not been studied at shorter wavelengths that may be considered X-rays.


Both SIMBAD and NASA seem to be in agreement that electromagnetic radiation around 10 nm is the somewhat arbitrary cutoff between extreme ultraviolet and super soft X-rays.

An initial question to answer is "What is the wavelength range of soft or super soft X-rays per a primary source?"

In the external links below is "Google Advanced Scholar Search". In your second window, click on this link.

The second box from the top has "with the exact phrase". Try "soft X-ray range". Read the top entries to see if anyone states a range.

When I did this, the second entry had "the soft x-ray spectral range (∼100 eV to ∼2 keV)"[2]. To convert ~100 eV to wavelength, try using proportions and the Wikipedia article electronvolt.

Is the proportion that's usable: wavelength = (532 nm * 2.33 eV)/100 eV?

This gives ~100 eV to be ~12 nm or 120 eV to be 10.3 nm. So the somewhat arbitrary cut off between extreme ultraviolet and super soft X-rays at 10 nm seems okay. Do you agree?

Astronomical sourcesEdit

From your second window, try "Alpheratz" and "X-rays" on "Google Advanced Scholar Search" from the "External links" below.

Do any of the entries have "Alpheratz" juxtaposed near "X-rays"?

Sometimes primary sources do not use names for stars. Use the "External links" below and your second window to see if SIMBAD has other identifiers for Alpheratz (you may have to scroll down the page).

Try several of these, for example, "BD+28 4", "EUVE J0008+29.0", "Sirrah", or "TD1 31", with "X-ray" or "X-rays". Is there even one primary source that has detected X-rays from alpha Andromeda?

Changing an entryEdit

From your analysis of Alpheratz so far, is it an X-ray source?

If you like and the answer to the above question is "no", you can delete the entry from the "X-ray source in Andromeda" section below or annotate the entry to indicate that you checked at least a couple primary sources and so far the star(s) are not X-ray sources. Or, you can leave the entries as is and try another star.

X-ray sources in AndromedaEdit

Here the center of M31 is imaged by the Chandra X-ray Observatory. Credit: S. Murray, M. Garcia, et al., Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA) NASA Technical Rep.: Jay Norris.
  1. Alpheratz 2012.01.04CET18:42:34 SIMBAD article "V* alf And", EUVE, TD1. Marshallsumter 18:12, 4 January 2012 (UTC)
  2. Andromeda Galaxy 10 May 2012 at 15:37 Wikipedia article. Marshallsumter (talk) 00:05, 11 May 2012 (UTC). The Andromeda Galaxy is also known as M31, NGC 224, UGC 454, PGC 2557, 2C 56 (Core), LEDA 2557.
  3. Andromeda Galaxy NASA Astronomy Picture of the Day for January 21, 2000.[3] Marshallsumter (talk) 00:05, 11 May 2012 (UTC).
  4. Using "Andromeda Galaxy" and "X-rays" on Google Advance search: "We have observed 69 unresolved X-ray sources and seven diffuse or confused source regions in M31 with the Einstein Observatory."[4] "We used the Einstein Observatory (Giacconi et al. 1979) on 1979 January 11-14 to study three fields in M31 with the imaging proportional counter detector (IPC), and one field with the high-resolution imaging detector (HRI)."[4] --Marshallsumter (talk) 17:48, 16 January 2013 (UTC).
  5. "It [M31] has been detected previously as an aggregate source in X-rays; for example, it is listed in the 4th Uhuru catalog by Forman et al. (1978) and in the Ariel catalog by Cooke et al. (1978), and was detected in soft X-rays by Margon et al. (1974)."[4] --Marshallsumter (talk) 17:55, 16 January 2013 (UTC).
  6. The early Uhuru catalog contains three astronomical X-ray sources within the constellation Andromeda: 2U 0022+42, 2U 0033+24, and 2U 0043+32.[5] Each of these was confirmed later: 2U 0022+42 at 3U 0021+42, 2U 0033+24 at 3U 0032+24, and 2U 0043+32 at 3U 0042+32. Any of these three may be the first X-ray source in Andromeda, Andromeda X-1. According to the NASA/IPAC Extragalactic Database, 2U 0022+42, 2U 0033+24, and 2U 0043+32 do not correspond nor are they close to any detected X-ray source in Messier 31 (M31), the Andromeda Galaxy.[6] So it is unlikely that M31 was Andromeda X-1. SIMBAD places 4U 0037+39 which is apparently the 4U equivalent of 2U 0022+42 in M31. The earliest apparent detection of X-rays from Andromeda occurred in 1971 at equatorial coordinates right ascension (RA) 00h 21m declination (Dec) +42° 00', 2U 0022+42, and is claimed from M31.[5] However, the last position for 2U 0022+42 listed in the fourth Uhuru catalog[7] at 4U 0037+39 is in M31. 4U 0037+39 is ~4.8° from 2U 0022+42. The error box for 2U 0022+42 has the corners: B1950.0 RA 00h 20m 48s Dec +43° 00' 00", RA 00h 20m 48s Dec +41° 00' 00", RA 01h 08m 00s Dec +43° 00' 00", and RA 01h 08m 00s Dec +41° 00' 00".[5] The more precise position for catalog entry 2U 022+42 is RA 00h 22m 05s Dec +42° 00' 00".[5] 4U 0037+39 is outside the error box for 2U 0022+42, although most of M31 is inside. --Marshallsumter (discusscontribs) 16:06, 11 January 2016 (UTC)

Non-X-ray sources in AndromedaEdit

  1. Alpheratz 14 December 2011 at 17:04 Wikipedia article "Alpha Andromedae". Marshallsumter 18:06, 4 January 2012 (UTC).
  2. Mirach Beta Andromedae on WikiSky: X-Ray 5 February 2012 at 05:33. Marshallsumter 18:05, 17 February 2012 (UTC). Mirach 2012.02.17CET19:07:40 SIMBAD article "NAME MIRACH", UV (TD1). Marshallsumter 18:13, 17 February 2012 (UTC)
  3. Almach γ1 Andromedae 12 October 2012 at 07:51 Wikipedia article "Gamma Andromedae". Almach 2013.01.16CET18:18:19 SIMBAD article "NAME ALMACH", K3IIb. --Marshallsumter (talk) 17:27, 16 January 2013 (UTC).

Oldest recordsEdit

The earliest apparent detection of X-rays from Andromeda occurred in 1971 at equatorial coordinates right ascension (RA) 00h 21m declination (Dec) +42° 00', 2U 0022+42, and is claimed from M31.[5]

The more precise position for catalog entry 2U 022+42 is RA 00h 22m 05s Dec +42° 00' 00".[5]

The error box for 2U 0022+42 has the corners: B1950.0 RA 00h 20m 48s Dec +43° 00' 00", RA 00h 20m 48s Dec +41° 00' 00", RA 01h 08m 00s Dec +43° 00' 00", and RA 01h 08m 00s Dec +41° 00' 00".[5] Most of M31 is inside the error box.


  1. The first X-ray source in Andromeda may have been the Andromeda Galaxy.

See alsoEdit


  1. Gordon Holman; Sarah Benedict (1996-09-23). Hard X-Rays, In: Solar Flare Theory Educational Web Pages. Goddard Space Flight Center. http://hesperia.gsfc.nasa.gov/sftheory/xray.htm. Retrieved 2011-03-09. 
  2. Steven Trent Manson; John W. Cooper (January 1968). "Photo-Ionization in the Soft x-Ray Range: 1Z Dependence in a Central-Potential Model". Physical Review 165 (1): 126-38. doi:10.1103/PhysRev.165.126. http://prola.aps.org/abstract/PR/v165/i1/p126_1. Retrieved 2012-01-04. 
  3. Robert Nemiroff; Jerry Bonnell; Jay Norris (January 21, 2000). Astronomy Picture of the Day. Greenbelt, Maryland: NASA Goddard Space Flight Center. http://apod.nasa.gov/apod/ap000121.html. Retrieved 2012-05-10. 
  4. 4.0 4.1 4.2 L. Speybroeck; A. Epstein; W. Forman; R. Giacconi; C. Jones; W. Liller; L. Smarr (November 15, 1979). "Observations of X-ray Sources in M31". The Astrophysical Journal 234 (11): L45-9. 
  5. 5.0 5.1 5.2 5.3 5.4 5.5 5.6 R. Giacconi; S. Murray; H. Gursky; E. Kellogg; E. Schreier; T. Tananbaum (1 December 1972). "The Uhuru catalog of X-ray sources". The Astrophysical Journal 178 (12): 261-308. doi:10.1086/151790. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1972ApJ...178..281G&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf. Retrieved 2016-01-10. 
  6. NED results for object MESSIER 031. Pasadena, California USA: Caltech. 11 January 2016. http://ned.ipac.caltech.edu/cgi-bin/objsearch?objname=M31&extend=no&hconst=73&omegam=0.27&omegav=0.73&corr_z=1&out_csys=Equatorial&out_equinox=J2000.0&obj_sort=RA+or+Longitude&of=pre_text&zv_breaker=30000.0&list_limit=5&img_stamp=YES. Retrieved 2016-01-11. 
  7. W Forman; C Jones; L Cominsky; P Julien; S Murray; G Peters (December 1978). "The fourth Uhuru catalog of X-ray sources". The Astrophysical Journal Supplemental Series 38 (12): 357-412. doi:10.1086/190561. http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1978ApJS...38..357F&link_type=ARTICLE&db_key=AST&high=555927d52a08280. Retrieved 2016-01-11. 

Further readingEdit

External linksEdit

{{Radiation astronomy resources}}

{{Principles of radiation astronomy}}