The radial velocity variations of the Na I D lines for the high-latitude supergiant star 89 Her

AbstractA survey of F, G, and W supergiants has been carried out with the DAO radial velocity spectrometer, an efficient instrument for detecting low-amplitude velocity variations in cool stars. Observations of 78 stars over five seasons show generally good agreement with OORAVEL results for spectroscopie binaries. The majority of supergiants show low-amplitude variability, with amplitudes typically 1 to 2 km s−1. The width of the cross-correlation profile has been measured for 58 supergiants. It reveals 14 stars with unusually broad lines, indicative of rotation velocities of 15 to 35 km s−1. Several have short-period binary companions and may be in synchronous rotation. The other broad-lined stars are apparently single or with long orbital periods; they may be making their first transition from the main sequence to become red supergiants.

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Radial Velocities for the Pulsating Subdwarf B Star PG 1605+072

International Astronomical Union Colloquium ◽

10.1017/s0252921100016547 ◽

2002 ◽

Vol 185 ◽

pp. 376-377

Author(s):

V.M. Woolf ◽

C.S. Jeffery ◽

D.L. Pollacco

Keyword(s):

Radial Velocity ◽

Line Shape ◽

High Speed ◽

Radial Velocities ◽

Peak Amplitude ◽

Amplitude Ratios ◽

Time Line ◽

Photometric Observations ◽

Velocity Variations ◽

Over Time

AbstractWe have performed high-speed spectroscopy of the pulsating subdwarf B star PG 1605+072. Its radial velocity variations have frequencies similar to those reported from photometric observations. Peak amplitude ratios are different, probably as a result of power shifting between modes over time. Line-shape variations have also been detected.

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Masers as probes of proto-planetary discs

Symposium - International Astronomical Union ◽

10.1017/s0074180900218263 ◽

2004 ◽

Vol 202 ◽

pp. 362-364

Author(s):

A.M.S. Richards ◽

R. J. Cohen ◽

M. Crocker ◽

E. E. Lekht ◽

V. Samodourov ◽

...

Keyword(s):

Radial Velocity ◽

Radio Telescope ◽

Keplerian Orbit ◽

Proper Motions ◽

Central Mass ◽

Maser Emission ◽

Star Forming ◽

Star Forming Regions ◽

Velocity Variations ◽

Water Maser

Water maser emission from star forming regions has been monitored for several decades using the Puschino radio telescope, showing radial velocity variations consistent with material in Keplerian orbit around protostars. MERLIN and the EVN are now being used to image the 22 GHz emission on au scales and measure proper motions. This will distinguish discs from outflows, and provide an estimate of the central mass and possibly orbiting condensations.

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The Long-term Variation in the RV Tauri Star U Mon

International Astronomical Union Colloquium ◽

10.1017/s025292110003774x ◽

1995 ◽

Vol 155 ◽

pp. 409-410 ◽

Cited By ~ 4

Author(s):

Karen R. Pollard ◽

P. L. Cottrell

Keyword(s):

High Resolution ◽

Light Curve ◽

Radial Velocity ◽

Tauri Star ◽

Short Term ◽

Instability Strip ◽

Term Variation ◽

Velocity Variations

The RV Tauri stars are semiregular pulsating variables located in the brightest part of the Cepheid II instability strip. They have a characteristic light curve of alternating deep and shallow minima. A subset of the RV Tauri stars (the RVb subclass) exhibit long-term (500 to 2600 day) light and radial velocity variations. Although it is well established that the short-term variations are due to pulsations, the long-term behaviour is not well understood.BVRI photometry and high-resolution spectra of U Mon (the brightest member of the RVb subclass) were obtained at the Mt John University Observatory (MJUO) between 1990 Aug and 1994 May. The light and colour curves obtained clearly show the long-term variation in U Mon (Fig. 1(a) and (b)). The reddest colours occur slightly later than the long-term minimum in the light curve. The short-term light and colour variations are ‘damped’ at the long-term minimum.

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Binaries among the WN population in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900211911 ◽

2003 ◽

Vol 212 ◽

pp. 180-181

Author(s):

Cédric Foellmi ◽

Anthony F.J. Moffat ◽

Martín A. Guerrero Roncel

Keyword(s):

Radial Velocity ◽

Magellanic Clouds ◽

Photometric Data ◽

Systematic Search ◽

X Ray ◽

Medium Resolution ◽

Velocity Variations

We have undertaken a large and extensive spectroscopic survey of WNE stars both in the SMC and LMC with various 2m and 4m telescopes, reaching a total of 78 nights, spread over three years, and obtaining over 1500 long-slit spectra of medium resolution. The first goal is a systematic search for binaries via periodic radial-velocity variations. We enlarged our dataset with photometric data from the ogle and macho databases, and with archival X-ray data from the ROSAT and Chandra satellites.

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Precise Radial Velocities

International Astronomical Union Colloquium ◽

10.1017/s025292110000614x ◽

1992 ◽

Vol 135 ◽

pp. 67-72

Author(s):

Gordon A.H. Walker

Keyword(s):

Radial Velocity ◽

Radial Velocities ◽

Velocity Variations ◽

Low Amplitude

AbstractCurrent techniques for the detection of long-term, low-amplitude (<50 m s−1), radial velocity variations are briefly reviewed together with some of their most successful programs. In the era of 8- to 10-m telescopes we must strive for a precision of < 1ms−1.

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