J/A+A/525/A148 Radial velocities in two globular clusters (Scarpa+, 2011)
Testing newtonian gravity with distant globular clusters: NGC 1851 and NGC 1904.
Scarpa R., Marconi G., Carraro G., Falomo R., Villanova S.
<Astron. Astrophys., 525, A148 (2011)>
=2011A&A...525A.148S 2011A&A...525A.148S
ADC_Keywords: Clusters, globular ; Radial velocities
Keywords: gravitation - globular clusters: general
Abstract:
Globular clusters are useful for testing the validity of Newtonian
dynamics in the low acceleration regime typical of galaxies, without
the complications of non-baryonic dark matter. In the absence of
disturbing effects, such as tidal heating, the velocity dispersion of
globular clusters is expected to vanish at large radii. If this is not
observed, and in particular if, as observed in elliptical galaxies,
the dispersion is found to be constant at large radii below a certain
threshold acceleration, this might indicate a breakdown of Newtonian
dynamics.
To minimize the effects of tidal heating that can increase the
velocity dispersion at large radii, we study the velocity dispersion
profile of two distant globular clusters, NGC 1851 and NGC 1904.
The velocity dispersion profile is derived from accurate radial
velocity measurements, obtained at the ESO 8m VLT telescope with the
FLAMES multi-object spectrograph. Reliable data for 184 and 146 bona
fide cluster star members were obtained for NGC 1851 and NGC 1904,
respectively.
Description:
Spectroscopic observations were obtained with FLAMES+GIRAFFE at the
ESO 8-meter VLT telescope. FLAMES is a fiber multi-object
spectrograph, allowing the simultaneous observation of up to 130
objects. For each configuration five separate 3200s exposures were
obtained on different night from November 2007 to March 2008.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 51 199 Radial velocities of stars in NGC 1851
table3.dat 51 173 Radial velocities of stars in NGC 1904
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Byte-by-byte Description of file: table2.dat table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq Sequential number within the table
5- 9 I5 --- ID ID number
11- 12 I2 h RAh Right ascension (J2000)
14- 15 I2 min RAm Right ascension (J2000)
17- 21 F5.2 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 33 F4.1 arcsec DEs Declination (J2000)
35- 39 F5.1 km/s HRV Heliocentric radial velocity
41- 43 F3.1 km/s e_HRV rms uncertainty on HRV
45- 46 I2 --- o_HRV Number of spectra available for this star
48- 51 F4.1 mag Vmag V magnitude
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 16-May-2011