2000AJ....120.1342K


Query : 2000AJ....120.1342K

2000AJ....120.1342K - Astron. J., 120, 1342-1350 (2000/September-0)

An extragalactic H I cloud with no optical counterpart?

KILBORN V.A., STAVELEY-SMITH L., MARQUARDING M., WEBSTER R.L., MALIN D.F., BANKS G.D., BHATAL R., DE BLOK W.J.G., BOYCE P.J., DISNEY M.J., DRINKWATER M.J., EKERS R.D., FREEMAN K.C., GIBSON B.K., HENNING P.A., JERJEN H., KNEZEK P.M., KORIBALSKI B., MINCHIN R.F., MOULD J.R., OOSTERLOO T., PRICE R.M., PUTMAN M.E., RYDER S.D., SADLER E.M., STEWART I., STOOTMAN F. and WRIGHT A.E.

Abstract (from CDS):

We report the discovery, from the H I Parkes All-Sky Survey (HIPASS), of an isolated cloud of neutral hydrogen, which we believe to be extragalactic. The H I mass of the cloud (HIPASS J1712-64) is very low, 1.7x107 M, using an estimated distance of ∼3.2 Mpc. Most significantly, we have found no optical companion to this object to very faint limits [µ(B)∼27 mag.arcsec–2]. HIPASS J1712-64 appears to be a binary system similar to, but much less massive than, H I 1225+01 (the Virgo H I cloud) and has a size of at least 15 kpc. The mean velocity dispersion measured with the Australia Telescope Compact Array (ATCA) is only 4 km.s–1 for the main component and, because of the weak or nonexistent star formation, possibly reflects the thermal line width (T<2000 K) rather than bulk motion or turbulence. The peak column density for HIPASS J1712-64, from the combined Parkes and ATCA data, is only 3.5x1019 cm–2, which is estimated to be a factor of 2 below the critical threshold for star formation. Apart from its significantly higher velocity, the properties of HIPASS J1712-64 are similar to the recently recognized class of compact high-velocity clouds. We therefore consider the evidence for a Local Group or Galactic origin, although a more plausible alternative is that HIPASS J1712-64 was ejected from the interacting Magellanic Cloud-Galaxy system at perigalacticon ∼2x108 yr ago.

Abstract Copyright:

Journal keyword(s): Galaxies: Formation - Galaxies: Irregular - Radio Emission Lines

Nomenclature: [KSM2000] HIPASS JHHMM+DD N=1, [KSM2000] HIPASS JHHMM+DD WW (Nos NE, SW).

Simbad objects: 18

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Number of rows : 18
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 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9998 1
2 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 6087 1
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 15682 1
4 M 105 LIN 10 47 49.600 +12 34 53.87   10.56 9.76 9.12 8.18 ~ 1403 0
5 NAME M96 Group GrG 10 48 +13.3           ~ 288 0
6 NGC 3384 GiG 10 48 16.897 +12 37 45.48   10.0       ~ 561 1
7 NAME HI 1225+01 HI 12 27 19 +01 30.4           ~ 78 1
8 NAME Cen A Group GrG 13 20 33.9 -44 58 51           ~ 242 0
9 LEDA 3097114 G 16 16 49.0 -55 44 57           ~ 10 1
10 [KSM2000] HIPASS J1712-64 SW PoC 17 11 35 -64 45.2           ~ 1 0
11 EQ J1712-64 HI 17 12 13 -64 39.2           ~ 2 1
12 [KSM2000] HIPASS J1712-64 NE PoC 17 12 35 -64 38.2           ~ 1 0
13 LEDA 3097116 G 17 12 35.0 -64 38 11           ~ 15 0
14 ICRF J181935.0-634548 Sy2 18 19 35.00241 -63 45 48.1926   16.80 14.40 13.4   ~ 139 1
15 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 1893 2
16 ICRF J193925.0-634245 Sy2 19 39 25.02671 -63 42 45.6255   18.87 18.37 17.64   ~ 1052 1
17 NAME Leo Ring HI ~ ~           ~ 45 0
18 NAME Local Group GrG ~ ~           ~ 7452 0

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2021.12.09-15:53:19

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