Understanding A-Type Supergiants. I, Ultraviolet and Visible Spectral Atlas

ASTRONOMY & ASTROPHYSICS JUNE I 1999, PAGE 351 SUPPLEMENT SERIES Astron. Astrophys. Suppl. Ser. 137, 351–362 (1999) Understanding A-type supergiants I. Ultraviolet and visible spectral atlas? of A-type supergiants,?? E. Verdugo1,A.Talavera2,andA.I.Gómez de Castro3 1 ISO Data Centre, P.O. Box 50727, E-28080-Madrid, Spain e-mail: [email protected] 2 LAEFF/INTA, P.O. Box 50727, E-28080-Madrid, Spain e-mail: ati@laeff.esa.es 3 Instituto de Astronom´ıa y Geodesia (CSIC-UCM), Fac. cc. Matemáticas, Universidad Complutense, Av. Complutense s/n, E-28040-Madrid, Spain e-mail: [email protected] Received October 14, 1997; accepted April 12, 1999 Abstract. This paper is the first of a series whose aim is number and the quality of the observational studies of stel- to perform a systematic study of A-type supergiant atmo- lar winds. At the same time the theory of stellar winds has spheres and winds. Here we present a spectral atlas of 41 been improved dramatically. However most of this work A-supergiants observed by us in high and medium reso- has been limited to O and B stars. To date, very few stud- lution in the visible and ultraviolet. The atlas consists of ies have been devoted to A-type supergiants. These stars profiles of the Hα,Hβ,Hγ,Hδ,H,CaII (H and K), Na I occupy a region of the HR diagram where evolution is (D1 and D2), Mg II4481,MgII [uv1] and Fe II [uv1, uv2, rapid and therefore they are few in number. Furthermore, uv3, uv62, uv63, uv161] lines for 41 stars with spectral the indicators of stellar winds are significantly weaker in types ranging from B9 to A9 and luminosity classes Ia, A-supergiants than in OB supergiants. Nevertheless it is Iab and Ib, and provides the basic data for a thoughtful known from the few A supergiants studied that the struc- study of these stars. The overall characteristics of the sam- ture of their stellar wind is unique in some way that is not ple as well as the data reduction procedures are described. yet understood. We also present some examples of spectral variability. There are no comprehensive studies of the line profiles formed in the winds of these stars, of which only a few Key words: atlases — line: profiles — stars: supergiants — have been studied in detail. In the optical, a photographic ultraviolet: stars survey of Hα emission in luminous O9 to A5 stars was undertaken by Rosendhal (1973) showing the strong influ- ence of luminosity upon the Hα profile in late-B and A supergiants. The emission at Hα disappears for stars fainter 1. Introduction than absolute visual magnitude −6.8to−7.0, while at the highest luminosities emission dominates over absorption. Mass loss is ubiquitous among highly luminous OBA stars. In the ultraviolet, where most of the indicators of mass UV The last decade has seen an enormous increase in the loss are observed, the P Cygni profiles for O and early B stars have been studied by a large number of authors. Send offprint requests to: E. Verdugo However the UV spectra of A-supergiants have scarcely ? Figures 1-3 are only available in electronic form at the been examined (e.g. Lamers et al. 1995; Lamers et al. 1978; http://www.edpsciences.com ?? Praderie et al. 1980; Underhill & Doazan 1982; Hensberge Based on observations made with the INT and JKT tele- et al. 1982); the most extensive study was performed scopes operated on the island of La Palma by the RGO in by Talavera & Gómez de Castro (1987) from the high the Spanish Observatorio del Roque de Los Muchachos of the Instituto de Astrofisica de Canarias, with the 2.2 m telescope resolution data available in the International Ultraviolet at Calar Alto Observatory, Spain, with the Bernard Lyot 2 m Explorer (IUE) satellite archive. They found two different telescope at Pic Du Midi Observatory, France and observations groups of A-supergiants: stars showing spectral lines char- collected at the European Southern Observatory at La Silla, acteristic of mass outflow and stars which do not show any Chile. sign of stellar winds in their spectrum. The mass-losing 352 E. Verdugo et al.: Understanding A-type supergiants. I. Table 1. Basic properties of the program stars Star Position (2000.0) mv Mv OB Assoc. Available data HD/BD Other name αδ Visible IUE BD +60 51 SAO 11196 00 26 33.7 +61 24 46 9.23 −4.80 Cas OB4 Y N HD 2928 SAO 11258 00 33 13.3 +62 32 14 8.61 −5.50 Cas OB4 Y Y HD 3940 SAO 11343 00 42 50.0 +64 17 28 7.26 −6.37 Cas OB7 Y Y BD +61 153 SAO 11344 00 42 59.1 +62 14 06 9.32 −4.69 Cas OB7 Y N HD 4717 SAO 11421 00 50 16.1 +63 10 17 8.9 −5.90 Cas OB7 Y N HD 5776 SAO 11519 01 00 32.8 +63 01 44 8.05 −4.97 Cas OB7 Y Y HD 12953 V472 Per 02 08 40.4 +58 25 25 5.67 −7.81 Per OB1 Y Y HD 13476 HR 641 02 13 41.5 +58 33 39 6.44 −7.10 Per OB1 Y Y HD 13744 SAO 23101 02 15 58.5 +58 17 37 7.59 −6.46 Per OB1 Y Y HD 14433 SAO 23243 02 21 55.3 +57 14 34 6.39 −6.89 Per OB1 Y Y HD 14489 i Per 02 22 21.3 +55 50 44 5.20 −7.84 Per OB1 Y Y HD 14535 SAO 23263 02 22 53.4 +57 14 42 7.44 −6.50 Per OB1 Y Y HD 15316 SAO 23374 02 29 58.6 +57 49 15 7.23 −6.48 Per OB1 Y Y HD 16778 SAO 23564 02 43 53.5 +59 49 22 7.71 −6.89 Per OB1 Y Y HD 236995 SAO 23582 02 45 03.4 +58 33 05 8.63 −4.77 Per OB1 Y N HD 17378 V480 Per 02 49 30.6 +57 05 03 6.25 −7.81 Per OB1 Y Y HD 20041 HR 964 03 15 47.9 +57 08 26 5.79 −6.60 Cam OB1 Y Y HD 21389 HR 1040 03 29 54.7 +58 52 43 4.54 −7.10 Cam OB1 Y Y HD 46300 13 Mon 06 32 54.2 +07 19 59 4.50 −4.80 Mon OB1 Y Y HD 59612 HR 2874 07 29 51.4 −23 01 28 4.85 −5.10 - Y Y HD 87737 η Leo 10 07 19.9 +16 45 45 3.52 −5.30 Sco-Cen N Y HD 92207 V370 Car 10 37 27.0 −58 43 60 5.46 −8.00 Car OB1 N Y HD 100198 V809 Cen 11 31 15.0 −61 16 42 6.31 −7.20 Car-Cen N Y HD 100826 SAO 251469 11 35 42.3 −61 17 16 6.29 −5.40 NGC 3766 N Y HD 102878 HR 4541 11 50 27.2 −62 38 57 5.70 −7.00 Cru OB1 Y Y HD 103516 HR 4563 11 54 59.9 −63 16 44 5.90 −4.90 Car-Cen N Y HD 104035 HR 4578 11 58 47.7 −64 20 21 5.61 −5.20 Car-Cen N Y HD 104111 SAO 251670 11 59 25.6 −62 49 51 6.37 - - N Y HD 161912 iot02 Sco 17 50 11.0 −40 05 25 4.81 −4.70 - N Y HD 187983 HR 7573 19 52 01.4 +24 59 32 5.57 −6.50 Vul OB4 Y N HD 197345 α Cyg 20 41 25.8 +45 16 49 1.25 −8.55 Cyg OB7 Y Y HD 207260 ν Cep 21 45 26.9 +61 07 15 4.30 −6.82 Cep OB2 Y Y HD 207673 HR 8345 21 49 40.0 +41 08 56 6.48 −4.97 - Y Y HD 209900 SAO 34034 22 05 13.7 +53 30 37 8.71 −4.85 Cep OB1 Y N HD 210221 HR 8443 22 07 25.5 +53 18 27 6.14 −5.00 Cep OB1 Y Y HD 211971 SAO 34314 22 19 25.6 +60 08 52 6.90 −5.50 Cep OB2 Y Y HD 212593 4 Lac 22 24 30.9 +49 28 35 4.56 −5.86 Lac OB1 Y Y HD 213470 SAO 34531 22 30 18.6 +57 13 32 6.65 −7.09 Cep OB1 Y Y BD +60 2542 SAO 20639 23 27 05.6 +61 22 42 8.82 −5.09 Cas OB2 Y N HD 223385 6 Cas 23 48 50.1 +62 12 52 5.43 −8.22 Cas OB5 Y Y HD 223960 SAO 20923 23 53 49.9 +60 51 13 6.93 −6.90 Cas OB5 Y Y Note: Y ≡ Observed. N ≡ Not observed. stars showed absorption shortward shifted components in to be not applicable to A-supergiants. However, the lat- the Mg II,FeII,CII,SiII and Al II lines. Moreover these est theoretical progress on this point (Achmad et al. 1997; components are variable, as well as the terminal velocity McCarthy et al. 1997; Kudritzki et al. 1997) has begun to measured from the violet edge of the resonance Mg II lines. clarify such discrepancies in the radiatively driven wind Contrary to the relation found by Abbot (1978) for radia- theory frame.

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