2009ApJ...698.1437K

Query : 2009ApJ...698.1437K

2009ApJ...698.1437K - Astrophys. J., 698, 1437-1455 (2009/June-3)

The Hα galaxy survey. VIII. Close companions and interactions, and the definition of starbursts.

KNAPEN J.H. and JAMES P.A.

Abstract (from CDS):

We consider the massive star formation properties, radial profiles, and atomic gas masses of those galaxies in our Hα Galaxy Survey that have close companion galaxies, in comparison with a matched control sample of galaxies without companions. Our analysis is based on Hα and continuum images of 327 disk galaxies that form a representative sample of the local universe. We find that the presence of a close companion raises the star formation rate by a factor of just below two, while hardly at all increasing the equivalent width of the Hα emission. This means that although statistically galaxies with close companions form stars at a higher rate, they do this over extended periods of time and not as bursts. We find no significant increase in the central concentration of the star formation as a result of the presence of a close companion. The fraction of truly interacting or merging galaxies is very small in the local universe, at around 2%, and possibly 4% of bright galaxies. Most of these interacting galaxies currently have unremarkable star formation properties. We also study the properties of the galaxies in the survey with the most extreme values for star formation indicators such as rate, equivalent width, star formation rate per area, and gas-depletion timescale. We find that each of these indicators favors a different subset of galaxies, and use this information to discuss critically the possible definitions of the term starburst to describe galaxies with enhanced star formation activity. We conclude that no one starburst definition can be devised that is objective and generally discriminant. Unless one restricts the use of the term "starburst" to a very small number of galaxies indeed, the term will continue to be used for a heterogeneous and wide-ranging collection of objects with no physical basis for their classification as starburst. Our overall conclusions are that (1) whereas the rare interacting and merging galaxies may have enhanced star formation, and vice versa, those galaxies with the highest star formation are often interacting or merging, the influence of the presence of a close companion on the star formation in galaxies is in general very small, and long lasting; and (2) the term "starburst" cannot be easily defined objectively and generally in physical terms.

Abstract Copyright: ∼

Journal keyword(s): galaxies: general - galaxies: interactions - galaxies: irregular - galaxies: spiral - galaxies: starburst

Simbad objects: 56

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Number of rows : 56
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 NGC 470 GiP 01 19 44.8526263032 +03 24 36.027176544 12.63 12.53 11.78     ~ 287 1
2 NGC 474 GiP 01 20 06.6870520512 +03 24 55.861973100 12.75 12.37 11.51 11.42 10.56 ~ 371 1
3 NGC 972 G 02 34 13.3574389680 +29 18 40.604917356   12.1 13.63     ~ 178 2
4 NGC 1056 Sy2 02 42 48.2914236192 +28 34 26.660028468   13.5       ~ 180 0
5 NGC 1156 GiG 02 59 42.8528847264 +25 14 28.352017320 12.13 12.32 11.74     ~ 323 1
6 Z 327-6 H2G 03 48 20.731 +70 07 58.37   14.6       ~ 142 2
7 Z 327-9 GiG 03 50 15.0019023336 +70 05 40.328180844   15.5       ~ 75 1
8 NGC 2146 AGN 06 18 37.710 +78 21 25.27 11.67 11.38 10.59     ~ 765 2
9 NGC 2337 rG 07 10 13.6374445464 +44 27 26.716619844   13.1       ~ 94 1
10 NGC 2276 AG? 07 27 14.485 +85 45 16.20   12.3       ~ 393 0
11 NGC 2363 AG? 07 28 29.59 +69 11 34.3   15.5       ~ 262 1
12 NGC 2363A HII 07 28 42.8 +69 11 21           ~ 588 3
13 NGC 2366 H2G 07 28 52.4529 +69 12 38.859 12.25 11.86 11.39 11.33   ~ 801 0
14 NGC 2648 GiP 08 42 39.8009205504 +14 17 08.220107076   12.80 11.82     ~ 91 0
15 NGC 2681 LIN 08 53 32.7183058512 +51 18 49.159212120 11.40 11.09 10.29     ~ 332 1
16 NAME M 81-82 Group GrG 09 55 +69.1           ~ 758 0
17 NGC 3077 GiP 10 03 19.0965510921 +68 44 01.556166166 11.23 10.85 10.14 9.74   ~ 808 0
18 NGC 3256 Sy2 10 27 51.284 -43 54 13.55   11.83 11.33 10.62 11.9 ~ 920 2
19 NGC 3310 AGN 10 38 45.85707 +53 30 11.8940   12.45 12.15     ~ 809 1
20 NGC 3593 GiG 11 14 36.9731893800 +12 49 05.497790664   11.8       ~ 376 2
21 NGC 3690 IG 11 28 31.0 +58 33 41   13.19 12.86     ~ 1015 4
22 NGC 3690B GiP 11 28 31.02 +58 33 40.7   11.8       ~ 635 4
23 NGC 3690NE AGN 11 28 33.07 +58 33 54.2   11.8       ~ 635 4
24 NGC 3769 GiP 11 37 44.0727836208 +47 53 34.782808956   11.7       ~ 195 0
25 NGC 3893 GiG 11 48 38.207 +48 42 38.84   11.23 10.67     ~ 391 1
26 NGC 3896 GiP 11 48 56.382 +48 40 28.79   14.05 13.57     ~ 94 0
27 NGC 3930 GiG 11 51 46.025 +38 00 54.48   13.5       ~ 89 0
28 NGC 3949 GiC 11 53 41.7311041896 +47 51 31.401451476   10.9       ~ 351 1
29 NGC 4064 GiG 12 04 11.191 +18 26 36.42   12.5       ~ 186 0
30 NGC 4088 AGN 12 05 34.2230093952 +50 32 21.064017876   11.2       ~ 428 1
31 NGC 4102 Sy2 12 06 23.11513 +52 42 39.4160   11.8       ~ 449 1
32 NGC 4237 AGN 12 17 11.4198657984 +15 19 26.557164264   12.3       ~ 266 0
33 NGC 4245 GiG 12 17 36.7836585312 +29 36 28.898544204   12.4       ~ 192 0
34 NGC 4253 Sy1 12 18 26.5163572920 +29 48 46.531535472   14.34 13.57     ~ 1106 1
35 NGC 4293 LIN 12 21 12.891 +18 22 56.64   11.6       ~ 311 2
36 NGC 4299 GiC 12 21 40.548 +11 29 59.74   12.8       ~ 271 0
37 NGC 4394 GiP 12 25 55.6366312872 +18 12 50.110707636   11.9       ~ 379 0
38 APG 277 IG 12 54 49.9 +02 38 57           ~ 59 1
39 NGC 4810 GiP 12 54 51.4796706960 +02 38 16.213538760   14.8       ~ 67 1
40 Mrk 59 rG 12 59 00.288 +34 50 42.45           ~ 319 2
41 NGC 4861 H2G 12 59 02.340 +34 51 33.98   12.90 12.32     ~ 389 2
42 NGC 5253 rG 13 39 55.990 -31 38 24.11 11.48 10.94 10.49 10.33 13.47 ~ 1421 4
43 NGC 5477 AG? 14 05 33.318 +54 27 37.85 13.94 14.36 14.01     ~ 224 1
44 NGC 5774 GiP 14 53 42.46224 +03 34 56.9532   13.9 12.94     ~ 168 1
45 NGC 5775 GiG 14 53 57.653 +03 32 40.10   13.0 11.34     ~ 460 2
46 IC 1127 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 3090 4
47 NGC 5962 GiP 15 36 31.6809457296 +16 36 27.933030504 12.04 11.98 11.34     ~ 258 1
48 NGC 6217 AGN 16 32 39.2100852960 +78 11 53.487076092   14.37 13.88     ~ 320 0
49 NGC 6240 Sy2 16 52 58.9 +02 24 03   14.31 13.37     ~ 1734 2
50 NGC 6951 Sy2 20 37 14.1228088488 +66 06 20.049916392   11.64 10.65     ~ 553 2
51 Z 426-19 AG? 21 12 20.471 +12 36 42.31   15.6       ~ 18 0
52 NGC 7479 Sy2 23 04 56.6432243448 +12 19 22.357387020 11.74 11.60 10.85 10.47 9.66 ~ 783 2
53 NGC 7541 GiG 23 14 43.857 +04 32 02.04   12.7       ~ 333 1
54 NGC 7714 AGN 23 36 14.1257730600 +02 09 18.197422668   14.91 14.36     ~ 788 1
55 APG 284 PaG 23 36 19 +02 09.3   12.6       ~ 608 0
56 NGC 7715 GiP 23 36 21.768 +02 09 25.30   11.81 12.14     ~ 142 0

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