Catalog of Galactic OB Stars

Catalog of Galactic OB Stars

B. Cameron Reed

Department of Physics

Alma College

Alma, Michigan 48801

e-mail:

(989) 463–7266

Last Update:2 March 2011

Contents

1.Introduction

2.Strategy

2.1 UBV Photometry

2.2Spectroscopy

2.3uvby Photometry

3. Format information for Catalog and Databases

4.Remarks On Individual Stars

5.References in Numerical Order

6.References in Alphabetical Order

Acknowledgements

Much of the spectroscopic data for the southern Case-Hamburg stars were checked and keypunched by Amy Beatty. This research has made use of the Simbad database, operated at CDS, Strasbourg, France, and of the WEBDA database. I am grateful to the inter-library loan staff at Alma College for tracking down a number of references, and to the Office of the Provost of Alma College for support of publication costs. Special thanks are due Brian Skiff of Lowell Observatory for forwarding me coordinates and cross-identifications for a number of objects. This research was supported at various times by awards from Research Corporation and the RUI program of the National Science Foundation (AST-9731179).

1. Introduction

This project originated in the summer of 1991 when I began compiling a cross-reference “catalog” and tabulation of published UBV photometry for stars listed in Stephenson and Sanduleak’s Luminous Stars in the Southern Milky Way [Publ. Warner & Swasey Obs., Vol. 1, no. 1 (1971)]. This database was published in July 1993 [ApJS 87, 367 (1993)] and was subsequently expanded to include compilations of published MK classifications [ApJS 97, 189 (1995)], 4-color photometry [AAS 117, 313 (1996)] and radial velocities [AJ 113, 823 (1997)] for these objects. In mid-1997 the project was again expanded to include UBV photometry for stars listed in the northern-hemisphere volumes of the “Case-Hamburg” surveys [ApJS 115, 271 (1998)]; MK classifications for the northern stars were similarly compiled and made electronically available to interested parties though were not formally published. Work on the radial velocity compilation has since been discontinued but interested readers may still obtain those (for the LS-South stars) from the author. As of this writing (December 2005), 4-color (Stromgren b-y, m1, c1) data have not been systematically searched for, but essentially all 4-color data available from (over 1100) references compiled for the UBV and MK databases has been incorporated. However, as 4-color and Hphotometry are often done together this should capture much of the Stromgren photometry available for OB stars.

The “Case-Hamburg” (CH) surveys comprise a seven-volume listing of intrinsically luminous stars within about ten degrees of the plane of the Milky Way. These objects are hereafter referred to as “LS” objects. The seven volumes were published between 1959 and 1971 by the Hamburg and Warner and Swasey Observatories. Most of the LS objects are OB stars, but there are as well a number of A, F, and G supergiants and a few white dwarfs and Wolf Rayet stars. These surveys reached a limiting photographic magnitude of approximately 13.5, and were based on objective-prism surveys of dispersion 580 Angstrom per millimeter at H. Six of the LS volumes cover the northern Milky Way:

Hardorp, J., Rohlfs, K., Slettebak, A. and Stock, J. 1959, Luminous Stars in the Northern Milky Way I. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

Stock, J., Nassau, J. J. and Stephenson, C. B. 1960, Luminous Stars in the Northern Milky Way II. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

Hardorp, J., Theile, I. and Voigt, H. H. 1964, Luminous Stars in the Northern Milky Way III. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

Nassau, J. J., and Stephenson, C. B. 1963, Luminous Stars in the Northern Milky Way IV. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

Hardorp, J., Theile, I. and Voigt, H. H. 1965, Luminous Stars in the Northern Milky Way V. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

Nassau, J. J., Stephenson, C. B. and MacConnell, D. J. 1965, Luminous Stars in the Northern Milky Way VI. (Hamburg-Bergedorf: Hamburger Sternwarte and Warner and Swasey Observatory).

The southern survey was published in a single volume:

Stephenson, C.B., and Sanduleak, N. 1971, Luminous Stars in the Southern Milky Way, Publ. Warner & Swasey Obs., Vol. 1, no. 1.

By the end of the year 2000 the author’s databases had grown to incorporate over 33,000 observations (lines of data) on just over 8500 CH stars drawn from 680 references. The strategy and procedures used in compiling these databases of LS-star data are detailed in section 2 below. The remainder of this introduction describes further expansion of the catalog and databases.

While engaged in the LS-star compilations I became aware that there exist many galactic OB stars not listed in the CH surveys. There are a number of reasons for this: many lie outside the sky coverage of those volumes or reside in crowded clusters and associations, while yet others are fainter than the CH limiting magnitude.

Motivated by encouragement from various colleagues, I decided in early 2001 to undertake supplementing my database to include identifications, UBV photometry, MK classifications, and some uvby photometry for “non CH” galactic OB stars.

The definition of an OB star is somewhat loose. Since the original LS catalogs were based on spectroscopic criteria my initial inclination was to only incorporate as so-called “supplemental OB stars” objects known to be such on the basis of their spectra. However, I quickly came to realize that such a criterion would discriminate against many likely OB stars. Thus I decided to relax my definition to include both spectroscopically-detected OB stars and stars whose UBV-based Q-values are indicative of an early type. My working definition(s) of an OB star can be summarized as:

(i)“Apparently normal” main sequence stars down to and including temperature class B2.

(ii)“Apparently normal” stars of luminosity class I-IV down to and including temperature class B9.

(iii)If spectral information is not available, “apparently normal” stars with Q –0.667. This Q-value corresponds to approximately type B2 on the main sequence and will catch supergiant B stars down to about temperature type B6.

To keep the work tractable and to avoid incorporating as few non-OB stars as possible, I as a rule incorporated as supplemental OB stars only objects for which photometry and/or MK-type classifications have been published, although this rule was not always rigidly followed. That is, suspected OB stars (for example, based on low-dispersion objective prism spectra or photographic photometry) are not as a rule included.

My search for supplemental OB stars went along the following general lines.

I began by examining the approximately 680 papers I had on hand that contained data for CH stars, beginning with particular ones that were expected to be rich in supplemental objects. The first of these were those papers giving photometry and classifications for objects appearing in the “Heidelberg” survey of galactic OB stars: Klare & Neckel [AAS 27, 215 (1977)]; Schild, Garrison & Hiltner [ApJS 51, 321 (1983)]; Garrison, Hiltner & Schild [ApJS 35, 111 (1976)]. While many Heidelberg (Hbg) and LS objects are in common, the Hbg catalog records some 560 early-type objects not appearing in the LS catalog. The general procedure was that as supplemental OB stars were recognized I added them to my master catalog of LS objects. Each star is assigned an internal “Alma LS” (ALS) number, a source name, cross-references to the BD, CPD, CD, SAO, HD and HR catalogs as appropriate, 2000-epoch right ascension and declination, and galactic coordinates. ALS numbers run from 1-5132 for CH southern stars, 6001-13390 for CH northern stars, and 14001 and up for “supplemental” OB stars. (ALS numbers 5133-6000 and 13391-14000 are not used.) Each supplemental star was queried on SIMBAD to locate any other published photometry or classifications; this often lead to new references to be examined.

After the Heidelberg objects I examined some historically “classic” papers: Hiltner’s tabulation of photometry, polarization measurements, and classifications for over 1200 O and B stars [ApJS 2, 389 (1956)], and Morgan, Code, & Whitford’s classifications for 1270 blue giants [ApJS 2, 41 (1955)] (see also Morgan, Whitford & Code [ApJ 118, 318 (1953)]). Hiltner et. al. [ApJ 157, 313 (1969)] published classifications for HR-numbered southern OB stars. Another major source of objects was Deutschman, et. al’s photometry of Celescope objects [ApJS 30, 97 (1976)]. More recently, Philip Massey and his various collaborators have uncovered numerous previously undetected OB stars in rich clusters and associations (such as Eta Car) via deep CCD photometry [e.g., AJ 105, 980 (1993); ApJ 454, 151 (1995); AJ 101, 1408 (1991); AJ 106, 1906 (1993); AJ 121, 1050 (2001)].

Less synoptic but still valuable surveys for OB stars have been carried out by a number of groups. Lynga [Lund. Medd. Astron. Obs. Ser. II, 141, 1 (1964)] published coordinates for some 400 putative OB stars, about 90 of which are new to my catalog. The La Plata, Argentina, group has been very active along these lines: Muzzio [AJ 79, 959 (1974)] and Orsatti [AJ 104, 590 (1992)] have published surveys for OB stars for which some follow-up photoelectric photometry has been published [Muzzio & Forte AJ 80, 1037 (1975)]. In such cases I incorporated no stars whose identification as early types would have been based only on photographic Q-values. Lanning and his collaborators [PASP 85, 70 (1973); PASP 106, 38 (1994); PASP 107, 751 (1995); PASP 110, 586 (1998)] have identified 351 UV-bright objects in the galactic plane, including a number of LS stars. However, many of these are white dwarfs, planetaries, dwarf novae and the like, so I did not as a rule incorporate these objects into my catalog unless information gleaned from SIMBAD indicated that they could reasonably be construed to be OB stars; likewise for Stephenson and Sanduleak’s [ApJS 33, 459 (1977)] listing of 455 H-alpha emission stars in the Milky Way. Drilling and Bergeron [PASP 107, 846 (1995)] published a list of 234 stars as an “extension” to the CH surveys, which prompted me to include those not previously picked up even though their list probably includes some non-OB types.

Beyond “survey-type” papers, OB stars appear in a number of papers dealing with individual clusters. In some cases where stars were identified only via finding charts I was able to determine coordinates from the RealSky set of CDs; in a few cases of ambiguity or extreme nebulosity I opted not to include objects. Ultimately, every one of the approximately 650 papers in my possession that had contributed CH-star data were examined for supplemental OB stars.

Two previous catalogs deserve mention here. Goy [AAS 26, 273 (1976)] prepared a catalog of 763 O-type stars, listing UBV photometry, polarizations, associated HII regions, and spectral types. Similarly, Garmany, Conti, and Chiosi [ApJ 263, 777 (1982)] compiled a listing of 765 O stars for which spectral types, luminosity class, and UBV photometry existed at that time. All but a handful of objects appearing in those catalogs appear in my catalog.

A difficult issue was whether or not to include as supplemental stars those objects for which Houk has given classifications in her Michigan Spectral Survey volumes. A search of those volumes revealed ~9300 stars that meet the criteria for “OB stars” given above but which I did not otherwise pick up. The majority of these are late B-type (B8-B9) giants. Given that Houk has a tendency to classify as too luminous, I opted not to include these objects.

In the text that follows, references to “LS” stars should be understood to generally mean “original Case-Hamburg LS stars plus supplemental OB stars” except where obvious from context. When it is necessary to distinguish between stars listed in the Northern/Southern CH volumes I refer to objects listed in the former (latter) as LSN (LSS) stars, respectively; otherwise, the generic label “LS” (luminous star) is used in reference to either CH or “supplemental” objects.

A few comments of a general nature are appropriate here. This catalog doubtlessly fails to include some legitimate OB stars even while it will no doubt prove to include a number of objects that it should not: the difference between a classification of B9 IV and A0 V is not great. In some cases judgment calls were made based on the source of a classification, the spectral dispersion, etc.

In December 2006, coordinates for LS-North Volume I stars were replaced with more accurate figures from Brian Skiff, who also pointed out a few new BD and HD cross-references.

2. Strategy

The primary criteria applied for incorporation of data into this compilation are originality and adherence to the UBV and MK systems.

In a compilation of this size, complete consistency is impossible to achieve: readers interested in any particular star are urged to treat this work as a sourcebook and consult original references whenever possible.
Various of the LSN volumes overlap in sky coverage, leading to duplicate entries for 153 stars. In addition, there is also some overlap between the LSS and LSN catalogs, leading to 151 stars in common. Note is made of these duplicates in the catalog, and care taken to assign data consistently to one star of a duplicate pair. In fields where the LSS and LSN volumes overlap in sky coverage, stars in close proximity to each other may appear in either a northern volume or in the Stephenson/Sanduleak volume; particular examples in this regard are stars in the open clusters NGC 6604 and 6611. Ordering the catalog by 2000-epoch right ascension alleviates some of this confusion but at the price of permuting the ordering of some LSS stars, whose numbers were originally assigned according as increasing 1900 right ascension.
It is also worth noting that in declination zone +54 of LSN Volume III, running numbers 1 through 15 are used twice, designating two different sets of stars. In these cases one looks to magnitudes, coordinates, and cross-identifications that appear in the original literature to establish what star is involved.

FORTRAN format codes for reading the catalog and UBV and MK databases are given in section 3 below. This is followed by detailed notes for some stars, and by a complete list of references.

2.1 UBV Photometry
Excepting a very few values representing averaged observations, only photoelectric data reported in the original research literature have been incorporated. Care was taken to exclude any results adopted from or that derived from averaging or homogenizing data from different sources: what appears here is, as much as possible, unadulterated. V magnitudes deriving from uvby photometry have not been incorporated. A chronic problem area was the number of measurements reported for each star: while most authors state this explicitly, some give only a minimum number and others no details at all. If no information along these lines could be gleaned, the number of measurements was taken to be one.
2.2Spectroscopy
The general precepts used in assembling the photometric compilation are retained here: only original data from references directly available to the author have been incorporated. Most classifications derive from grating, prism, or objective-prism spectra; in a few instances they derive from equivalent widths, microphotometer tracings or the like.
Two particular complications arise when dealing with spectra. The first is that notations used to designate peculiarities (uncertain classification, emission, broadening, interstellar lines, double lines, etc.) differ from source to source and continue to evolve. Within the limits imposed in producing a printable collation I have attempted to remain faithful to original notations. The second is that there is an element of subjectivity to classification: two credible sources may legitimately assign different classifications to the same star; this is particularly so for luminosity classifications where low-dispersion spectra are involved. Except for resolving obvious cases of misidentification (a star classified as both B and K, for example), no attempt has been made to scan the compilation for such differences.
An important exception was made to the “original data only” precept in compiling spectral data: the catalog of L. F. Smith [reference 301; MNRAS 138, 109 (1968)] was used in its entirety, even though not all data therein is original to her. Her paper introduced a new classification system for the Wolf-Rayet stars and included re-classification of previous material on the new system. No supplemental stars appear in this reference.

Given that a wide variety of instruments and techniques underlie these classifications, a 20-character “dispersion record” is given for those classifications taken from papers where instrumental details were given. If no details were given, the dispersion record is left blank. These records follow a format where up to three items are detailed: (1) type of instrument used, (2) dispersion in Å/mm, and (3) the wavelength at which the dispersion applies. These dispersion records incorporate a number of abbreviations as follows:

A or ÅÅngstrom

dHydrogen delta

gHydrogen gamma

m/Amicrons per Ångstrom

CassCassegrain spectrum

1P1-prism

2P2-prism

3P3-prism

CCoude spectrum

GGrating spectrum (reflection or transmission not specified)

ITImage tube spectrum

OPObjective-prism

PPrism

RGReflection grating

SSlit

TG Transmission grating

TPThin prism

Examples: “126” in the dispersion record indicates that the original reference reported only a dispersion of 126 Å/mm. “OP 77g” would indicate an objective-prism spectrum of dispersion 77 Å/mm at H-gamma. “3P 36g” indicates a 3-prism spectrum of dispersion 36 Å/mm at H-gamma. “S 20” designates a slit spectrum of dispersion 20 Å/mm. The appearance of a question mark in parentheses indicates that the instrumental configuration was inferred from the original paper.

2.3uvby Photometry

See comments in the first paragraph under Introduction above. The author’s long-term intention is to undertake a systematic survey for uvby photometry as time permits.

3. Format information for Catalog and Databases

The tables below detail the various columns of data in the electronically-distributed versions of the galactic OB-star catalog and the UBV and MK databases.

The Catalog

Note that BD numbers are in the format +dd nnnn while CPD and CD numbers are in the format +dd nnnnn.

If a star does not have a given cross-identification, the entry for that column will appear blank.

I5Alma LS (ALS) number

A25Source name

A8BD number

A9CPD number

A9CD number

A6SAO number

A6HD number

A4HR number

A10Notes

F5.1Magnitude (dummy value = 99.9)

A1Source for magnitude: V = pe, P = pg, N = none

I2RA hours

I2RA minutes

F4.1RA seconds

A1Sign of declination

I2Declination degrees

I2Declination minutes

I2Declination seconds

F8.2Galactic longitude, degrees