OH/IR stars and the Galactic Centre distance

Using the VLA at 1612 MHz Lindqvist et al. (1992a) have found 134 OH/IR stars close to the Galactic Centre (GC). These stars plus 15 from Habing et al. (1983) have been used as probes of the gravitational potential to derive the mass distribution in the inner galactic bulge between ≈ 5 to ≈ 100 pc from the GC (Lindqvist et al., 1992b). In this paper we present a progress report of a dynamical model which we have applied to the data.

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A Southern Survey of OH Masers at 1612 MHz

Australian Journal of Physics ◽

10.1071/ph810333 ◽

1981 ◽

Vol 34 (3) ◽

pp. 333 ◽

Cited By ~ 22

Author(s):

JL Caswell ◽

RF Haynes ◽

WM Goss ◽

U Mebold

Keyword(s):

Galactic Plane ◽

Galactic Centre ◽

Emission Sources ◽

Classification Schemes ◽

Mira Variables ◽

Population Type ◽

Ir Stars ◽

Kinematic Properties ◽

Line Type

A search for OH at 1612 MHz has been made along the galactic plane from longitude 3400 to the galactic centre, yielding 78 emission sources (mostly new discoveries); a further 5 sources have been found in a less sensitive survey between longitudes 2700 and 3260 Of these 83 sources 55 are masers of the variety showing two intensity peaks spaced in velocity-a characteristic of OH/IR stars. The velocity and spatial distributions of these new OHjIR stars (which are not as yet identified in the optical or infrared) are discussed, with special reference to their kinematic properties and population type; it is still not clear whether they are predominantly late-type giants (Mira variables) or supergiants. The other 28 OH sources detected include 11 of the type lIe variety (extended OH clouds exhibiting 1612 MHz emission with accompanying 1720 MHz absorption) and 4 with accompanying main-line (type 1)OH masers; the remaining 13 sources do not readily fit within existing classification schemes and are discussed individually

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Possible Evidence for a Binary Massive Black Hole in the Galactic Nucleus

Symposium - International Astronomical Union ◽

10.1017/s0074180900229811 ◽

1996 ◽

Vol 169 ◽

pp. 285-286

Author(s):

E.J.A. Meurs

Keyword(s):

Black Hole ◽

Emission Line ◽

Velocity Component ◽

Orbital Motion ◽

Galactic Centre ◽

Line Profiles ◽

Radial Velocity Component ◽

Massive Black Hole ◽

Ir Stars ◽

Sgr A

The Galactic Centre candidate Sgr A∗ may exhibit a 40 km/s radial velocity component, which is not observed for OH/IR stars around the centre. This could be interpreted as orbital motion of one member of a binary massive black hole. In other galaxies such pairs may be inferred from radio jet precession and emission line profiles.

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OH/IR Stars Near the Galactic Centre

Planetary Nebulae ◽

10.1007/978-94-009-7094-6_95 ◽

1983 ◽

pp. 542-543 ◽

Cited By ~ 1

Author(s):

H. J. Habing ◽

F. M. Olnon ◽

A. Winnberg ◽

H. E. Matthews ◽

B. Baud

Keyword(s):

Galactic Centre ◽

Ir Stars

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86-GHz SiO masers in Galactic centre OH/IR stars

Publications of the Astronomical Society of Japan ◽

10.1093/pasj/psaa040 ◽

2020 ◽

Vol 72 (4) ◽

Author(s):

Maria Messineo ◽

Lorant O Sjouwerman ◽

Harm J Habing ◽

Alain Omont

Keyword(s):

Detection Rate ◽

Space Experiment ◽

Galactic Centre ◽

Maser Emission ◽

Circumstellar Material ◽

Spectral Peaks ◽

Ir Stars ◽

Molecular Transition

Abstract We present results on a search for 86.243-GHz SiO (J = 2→1, $v$ = 1) maser emission toward 67 OH/IR stars located near the Galactic centre. We detected 32 spectral peaks, of which 28 correspond to SiO maser lines arising from the envelopes of these OH/IR stars. In OH/IR stars, we obtained an SiO maser detection rate of about $40\%$. We serendipitously detected two other lines from OH/IR stars at ≈86.18 GHz, which could be due to a CCS-molecule transition at 86.181 GHz or probably to an highly excited OH molecular transition at 86.178 GHz. The detection rate of 86-GHz maser emission is found to be about $60\%$ for sources with the Midcourse Space Experiment (MSX) A − E < 2.5 mag; but it drops to $25\%$ for the reddest OH/IR stars with MSX A − E > 2.5 mag. This supports the hypothesis by Messineo (2002, A&A, 393, 115) that the SiO masers are primarily found in relatively thinner circumstellar material.

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OH/IR Stars Near the Galactic Centre

Symposium - International Astronomical Union ◽

10.1017/s0074180900094432 ◽

1983 ◽

Vol 103 ◽

pp. 542-543

Author(s):

H.J. Habing ◽

F.M. Olnon ◽

A. Winnberg ◽

H.E. Matthews ◽

B. Baud

Keyword(s):

Spatial Distribution ◽

High Velocity ◽

Surface Brightness ◽

Velocity Dispersion ◽

Galactic Centre ◽

Galactic Rotation ◽

Red Giants ◽

Large Array ◽

Very Large Array ◽

Ir Stars

We have detected 34 OH/IR stars within 1 degree of the galactic centre by their OH emission line at 1612 MHz (18 cm) using the Effelsberg 100 m telescope and the Very Large Array. The spatial distribution and the distribution of the radial velocities show that practically all stars are within 150 pc from the Galactic centre, and that the number of foreground objects is very small. The projected distribution of the stars is similar to that of the surface brightness at 2.4 μm. Since the 2.4 μm radiation is supposed to be due to red giants, the OH/IR stars are probably members of the same population. The stars have considerable random velocities (velocity dispersion in one coordinate of 150 ± 50 km s−1), but show general Galactic rotation. The high velocity dispersion is remarkable for objects of this population.

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