Sh 2-104

Coordinates: (74.74°, 0.61°)

Lahulla identifies two potential ionising stars: the O5 V [L85] S104 4 = [CGG78] S104 Anon 3 and the B0 V [L85] S104 3.

Avedisova gives a slightly cooler O6V class for the main ionising star. She places Sh 2-104 in the star forming region SFR 74.74+0.61 with the star cluster Dolidze 4 and the HII region DWB 14.

You can see a good image of this nebula here. Sh 2-104 is prominent in infrared as can be seen in this MSX 8μm image.

A 2003 study concludes that about 450 solar masses of gas form a shell around an ionising O6V star at a distance of 4000 +/- 500 parsecs. The abstract also adds "We present millimetre-line imaging of the Galactic H II region Sh 104. We show that it is surrounded by a ring of molecular gas and dust. Four large molecular condensations are regularly spaced around the ring. These condensations are themselves fragmented and contain several massive dense cores. A deeply embedded cluster is observed in the near IR towards the largest condensation. It contains at least one massive star ionizing an ultra-compact H II region. The Sh 104 region is a good illustration of the ``collect and collapse' model for star formation triggered by the expansion of an H II region." [1]

Identifies two potential ionising stars: the O5 V [L85] S104 4 and the B0 V [L85] S104 3 and gives a distance estimate of 4800 parsecs for Sh 2-104.[2]

Notes

1. ^ Deharveng, L., Lefloch, B., Zavagno, A., et al. (2003). "Triggered massive-star formation at the border of the H II Region Sh 104", Astronomy and Astrophysics, Vol. 408, L25-L28. [2003A&A...408L..25D]

2. ^ Lahulla, J. F. (1985). "UBVRI photometry of stars in several H II regions", Astronomy and Astrophysics Supplement Series, Vol. 61, 537-545. [1985A&AS...61..537L]

Distance estimates

4400 pc [1982ApJS...49..183B]
4800 pc [1985A&AS...61..537L]
4000 pc +/- 500 [2003A&A...408L..25D]
3480 pc +/- 800 [1984NInfo..56...59A]

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Sh 2-104

Most of the sources used to create these nebula descriptions are listed in the notes section for each description. In some cases, for example the Avedisova, Humphreys and Reed catalogs, the source is used extensively and is not listed in the individual nebula descriptions. See this catalog overview for more information on the catalogs and the general sources used to create these descriptions and this introduction to HII regions on the general history of this area of astronomy.

This image was created using the POSS-II/UKSTU data of the Digitized Sky Survey and SuperCOSMOS using the process described here.

According to my correspondence with the Royal Observatory Edinburgh and the Space Telescope Science Institute, I am allowed to use the POSS-II/UKSTU data to create and display images for non-commercial purposes so long as I include this fine print for the SuperCOSMOS data:

Use of these images is courtesy of the UK Schmidt Telescope (copyright in which is owned by the Particle Physics and Astronomy Research Council of the UK and the Anglo-Australian Telescope Board) and the Southern Sky Survey as created by the SuperCOSMOS measuring machine and are reproduced here with permission from the Royal Observatory Edinburgh.

and this acknowledgement taken from the DSS site:

The Digitized Sky Surveys were produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.

The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation.

The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt.

The "Second Epoch Survey" of the southern sky was made by the Anglo-Australian Observatory (AAO) with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1993-5 by the Anglo-Australian Observatory Board, and are distributed herein by agreement.

The "Equatorial Red Atlas" of the southern sky was made with the UK Schmidt Telescope. Plates from this survey have been digitized and compressed by the ST ScI. The digitized images are copyright ? 1992-5, jointly by the UK SERC/PPARC (Particle Physics and Astronomy Research Council, formerly Science and Engineering Research Council) and the Anglo-Australian Telescope Board, and are distributed herein by agreement.

The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement. The compressed files of the "Palomar Observatory - Space Telescope Science Institute Digital Sky Survey" of the northern sky, based on scans of the Second Palomar Sky Survey are copyright ? 1993-1995 by the California Institute of Technology and are distributed herein by agreement.