1996A&A...313..405B


Query : 1996A&A...313..405B

1996A&A...313..405B - Astronomy and Astrophysics, volume 313, 405-416 (1996/9-2)

On the nature of the UV turnup in early-type galaxies.

BICA E., BONATTO C., PASTORIZA M.G. and ALLOIN D.

Abstract (from CDS):

We study the UV turnup in early-type galaxies from coadded IUE spectra reaching an unprecedented signal to noise ratio. Some spectral groups resulted with strong or moderate UV turnup, while in others it is very weak or absent. We study the relationships of the UV turnup intensity with absolute magnitude, X-ray and Hα luminosities. Galaxies in the strong UV turnup groups are systematically bright, and have high X-ray and Hα emission luminosities; however, some other galaxies with the latter properties do not exhibit a significant UV turnup. The spectral groups with an important intermediate age component are far-UV weak. The contribution from an intermediate age population with varying strength might explain why some red stellar population early-type galaxies present the UV turnup while others do not. The available spectral groups have been further coadded into one with strong UV turnup and another one without it, and we analyse their difference. We compare the spectral slope of the isolated UV turnup with IUE spectra of various hot sources which had been proposed in previous studies to explain it. We conclude that only very hot stars like sdO and sdB subdwarfs, some nuclei of planetary nebulae or DO white dwarfs, have the proper slope to explain the UV turnup. The UV turnup as detected through the IUE aperture is not featureless: it presents absorptions similar to those observed in the galaxies with weak far-UV flux. These features appear to be the λ1400A and λ1600A ones, characteristic of moderately cool white dwarfs (DA5), which indicates that these stars are dominant flux contributors between λ1300-2000A in the far-UV weak groups. The cooling time of DA5 stars together with the evolutionary time since they left the main sequence, imply that they evolved from low-mass stars possibly associated with the initial burst of star formation in early-type galaxies and/or merger events at intermediate ages. On the other hand, two possible scenari are discussed for the origin of the hot component which causes the UV turnup, one related to late stages of normal evolution of low-mass stars, and another related to past nuclear activity events and jets which might have blown away the atmospheres of red giants in the central parts of the galaxies, exposing the hot stellar cores and mimicking a spectral distribution like that of the hottest stars observed.

Abstract Copyright:

Journal keyword(s): galaxies: elliptical and lenticular, cD - galaxies: general - galaxies: stellar content - ultraviolet: galaxies

Simbad objects: 77

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Number of rows : 77
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 M 32 IG 00 42 41.825 +40 51 54.61 9.51 9.03 8.08     ~ 2098 2
2 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11941 1
3 HD 4539 HS* 00 47 29.2193758344 +09 58 55.690280832 9.17 10.12 10.24     sdB 82 0
4 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10381 1
5 Feige 11 HS* 01 04 21.6747168600 +04 13 37.054495956 10.847 11.826 12.065 12.183 12.324 sdB2VIHe4 117 0
6 NGC 584 GiP 01 31 20.7231919800 -06 52 04.770287472 11.93 11.44 10.48     ~ 382 2
7 M 33 GiG 01 33 50.8965749232 +30 39 36.630403128 6.17 6.27 5.72     ~ 5541 1
8 NGC 1052 GiP 02 41 04.7997864552 -08 15 20.761481016 11.84 11.41 10.47 10.71   ~ 1241 2
9 NGC 1316 GiP 03 22 41.789 -37 12 29.52 9.81 9.15 8.53 7.66   ~ 1302 1
10 NGC 1399 BiC 03 38 29.083 -35 27 02.67 11.05 9.74 9.59 8.12   ~ 1519 1
11 NGC 1404 GiP 03 38 51.917 -35 35 39.81 11.53 10.69 10.00 9.03   ~ 718 1
12 NGC 1407 GiG 03 40 11.904 -18 34 49.36   10.64 9.67 9.13   ~ 556 1
13 NGC 1553 GiP 04 16 10.4697802536 -55 46 48.072797400 10.76 10.10 9.40 8.74   ~ 366 2
14 NAME NGC 1553 Group GrG 04 16 17 -56 10.8           ~ 4 0
15 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16265 1
16 X LMC X-3 HXB 05 38 56.6323605504 -64 05 03.317937504   17 17.2     B2.5Ve 649 0
17 V* U Gem CV* 07 55 05.2324414746 +22 00 05.044127985   15.3 14.54     DA 1081 0
18 V* HK Cnc HS* 08 59 02.6445309720 +11 56 27.841260300   13.47 13.480     sdB3VIIHe0 31 0
19 NGC 2768 SyG 09 11 37.504 +60 02 13.95 11.30 10.84 9.87     ~ 486 2
20 NGC 2865 GiG 09 23 30.205 -23 09 41.37   12.39 11.43 11.06   ~ 233 0
21 NGC 3115 GiG 10 05 13.9270507008 -07 43 06.982712292   11   9.37   ~ 977 2
22 NGC 3311 BiC 10 36 42.821 -27 31 42.02   11.93 10.93 10.00 9.67 ~ 286 2
23 M 105 LIN 10 47 49.600 +12 34 53.87   10.56 9.76 9.12 8.18 ~ 1426 0
24 Feige 38 HS* 11 16 49.3630906272 +06 59 33.203109948   12.77 13.03     sdB1.5VIIHe3 34 1
25 NGC 3998 SyG 11 57 56.1334044408 +55 27 12.922443432   11.64 12.10 10.09   ~ 610 2
26 V* GW Vir WD* 12 01 45.9731868264 -03 45 40.628670300   14.87 15.04     DOQZ1 476 0
27 NGC 4111 GiP 12 07 03.1334091672 +43 03 56.345868252 12.07 11.63 10.74     ~ 324 1
28 NGC 4125 GiP 12 08 06.017 +65 10 26.88 11.14 10.65 9.72     ~ 413 2
29 NGC 4151 Sy1 12 10 32.5759813872 +39 24 21.063527532   12.18 11.48     ~ 3546 2
30 NGC 4278 LIN 12 20 06.8253868 +29 16 50.713486 11.54 11.09 10.16     ~ 917 2
31 NGC 4350 GiP 12 23 57.814 +16 41 36.08   11.5 11.08     ~ 305 0
32 M 84 Sy2 12 25 03.74333 +12 53 13.1393 12.67 12.09 10.49     ~ 1708 2
33 M 85 GiP 12 25 24.053 +18 11 27.89   10.2       ~ 627 0
34 M 86 GiG 12 26 11.814 +12 56 45.49 10.32 9.83 8.90   7.50 ~ 1051 1
35 IC 3370 LIN 12 27 37.3278534168 -39 20 16.247588712   11.99 12.12 10.39   ~ 145 0
36 NAME Vir B GrG 12 29.8 +08 00           ~ 126 0
37 M 49 Sy2 12 29 46.798 +08 00 01.48   13.21 12.17     ~ 2034 2
38 M 87 BiC 12 30 49.42338230 +12 23 28.0438581 10.16 9.59 8.63   7.49 ~ 6738 3
39 NAME Virgo A Cluster ClG 12 30.8 +12 23           ~ 128 0
40 NGC 4494 GiP 12 31 24.0391348536 +25 46 30.071664120   10.55 9.74     ~ 462 0
41 PG 1230+052 HS* 12 33 12.5632632624 +04 57 37.603907964   13.26       sdB 22 0
42 M 89 LIN 12 35 39.8073444 +12 33 22.830809 11.29 10.73 9.75     ~ 962 2
43 NGC 4564 GiG 12 36 26.9869512504 +11 26 21.204472848 12.51 12.05 11.12     ~ 578 1
44 M 104 LIN 12 39 59.4302501832 -11 37 22.988264808 9.51 9.55 8.00 8.05   ~ 1338 3
45 M 59 GiG 12 42 02.2581375168 +11 38 48.909507756   11.0       ~ 675 0
46 M 60 GiP 12 43 39.9708251928 +11 33 09.688174056   10.3       ~ 1308 1
47 NGC 4697 GiG 12 48 35.8981498824 -05 48 02.482374564   10.97   9.83   ~ 835 0
48 NGC 4696 BiC 12 48 49.2724775784 -41 18 39.304053252   11.21   10.7   ~ 471 3
49 NGC 4742 GiG 12 51 48.0416784480 -10 27 17.196625800   12   11.55   ~ 216 1
50 NGC 4762 LIN 12 52 56.049 +11 13 50.88   11.1       ~ 348 0
51 NGC 4853 AGN 12 58 35.1979266912 +27 35 46.930900632 13.96 14.68 13.00 13.24   ~ 136 1
52 NGC 4874 LIN 12 59 35.7093764280 +27 57 33.293892204 13.01 13.7 11.40 12.122 11.386 ~ 758 3
53 NGC 4889 EmG 13 00 08.097 +27 58 37.29 12.93 13.0 11.30 11.652 10.906 ~ 677 1
54 NGC 5044 BiC 13 15 23.9607836592 -16 23 07.547751744   11.9   10.74   ~ 479 0
55 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2738 2
56 NGC 5670 GiG 14 35 36.0507300624 -45 58 01.018744572   12.96   11.35   ~ 44 0
57 IC 1065 Sy2 14 49 21.5927137128 +63 16 13.799495280   17.30 16.39     ~ 348 1
58 NGC 5846 BiC 15 06 29.253 +01 36 20.29   11.9   9.74   ~ 817 1
59 3C 338.0 QSO 16 28 38.2446374616 +39 33 04.235250060   12.78 11.78     ~ 731 5
60 PG 1707+427 WD* 17 08 47.6869215528 +42 41 00.558430656   16.18       PG1159 112 0
61 NGC 6388 GlC 17 36 17.461 -44 44 08.34   7.40       ~ 868 1
62 NGC 6441 GlC 17 50 13.06 -37 03 05.2   9.26 8.00     ~ 836 0
63 V* AM Her CV* 18 16 13.2546725112 +49 52 04.759613544   15.124 14.808 13.525   M4.5-5Ve 938 0
64 PN K 1-16 PN 18 21 52.1086837968 +64 21 53.406292104   14.44 14.96 15.26   PG1159 243 0
65 NGC 6624 GlC 18 23 40.51 -30 21 39.7           ~ 834 1
66 M 69 GlC 18 31 23.10 -32 20 53.1   9.32 8.31     ~ 440 1
67 HD 226868 HXB 19 58 21.6757355952 +35 12 05.784512688 9.38 9.72 8.91 8.42   O9.7Iabpvar 4138 0
68 NGC 6868 GiP 20 09 54.082 -48 22 46.25   11.58 9.22 10.01 7.91 ~ 214 1
69 PG 2110+127 HS* 21 13 21.0605578368 +12 57 09.221687280   13.12 12.96 12.98   sdB 20 0
70 V* IR Peg WD* 21 34 08.2124719240 +06 50 57.662044329   16.15       PG1159 115 0
71 NGC 7196 G 22 05 54.8107967352 -50 07 09.868854000   12.43 11.54 10.89   ~ 110 0
72 NGC 7293 PN 22 29 38.5454047152 -20 50 13.747242408 11.894 13.158 13.524 13.689 13.898 DAO.5 926 0
73 4C 11.71 QSO 22 49 54.5839920312 +11 36 30.818995056   14.4 13.01     ~ 171 2
74 NAME NGC 3998 Group GrG ~ ~           ~ 1 0
75 NAME NGC 221 Group GrG ~ ~           ~ 1 0
76 NAME NGC 3115 Group GrG ~ ~           ~ 10 0
77 NAME NGC 4853 Group GrG ~ ~           ~ 1 0

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2022.10.01-04:16:09

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