J/A+A/627/A4 Praesepe (NGC 2632) and its tidal tails (Roeser+, 2019)
Praesepe (NGC 2632) and its tidal tails.
Roeser S., Schilbach E.
<Astron. Astrophys. 627, A4 (2019)>
=2019A&A...627A...4R 2019A&A...627A...4R (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Populations, stellar
Keywords: open clusters and associations: individual: Praesepe
Abstract:
Within a 400pc sphere around the Sun, we search for Praesepe's tidal
tails in the Gaia Data Release 2 (DR2) data set. We used a modified
convergent-point method to find stars with space velocities close to
the space velocity of the Praesepe cluster. We find a clear indication
for the existence of Praesepe's tidal tails, both extending up to
165pc from the centre of the cluster. A total of 1393 stars populate
the cluster and its tails, giving a total mass of 794M☉. We
determined a tidal radius of 10.77pc for the cluster and a tidal mass
of 483M☉. The corresponding half-mass radius is 4.8pc. We also
found a clear indication for mass segregation in the cluster. The
tidal tails outside 2 tidal radii are populated by 389 stars. The
total contamination of our sample by field stars lies between 50 and
100 stars or 3.6-7.2%. We used an astrometrically and photometrically
clean subsample of Gaia DR2, which makes our Praesepe sample
incomplete beyond M∼12.0mag; this corresponds to about 0.25M☉. A
comparison with an N-body model of the cluster and its tails shows
remarkably good coincidence. Three new white dwarfs are found in the
tails.
Description:
All parameters based on or derived from Gaia DR2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stars.dat 80 1393 All the stars shown in Figures 2 and 3
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: stars.dat
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Bytes Format Units Label Explanations
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3- 21 I19 --- Source Gaia DR2 source id (source_id)
23- 34 F12.8 deg RAdeg Gaia DR2 right ascension (ICRS at Ep=2015.5)
rounded to 10-8 degrees
36- 47 F12.8 deg DEdeg Gaia DR2 declination (ICRS at Ep=2015.5)
rounded to 10-8 degrees
49- 56 F8.4 mag Gmag G-band mean magnitude (Vega) (photgmean_mag)
58- 63 F6.2 km/s dvpar Velocity parallel to the convergent point (1)
65- 70 F6.2 km/s vpero Velocity perpendicular to the convergent point (2)
72- 80 E9.3 --- pcont Probability of being contaminated (3)
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Note (1): dvtan is the difference between the observed velocity and the
predicted velocity parallel to the convergent point in the tangential plane
(see paper).
Note (2): vpero is the observed velocity perpendicular to the convergent point
in the tangential plane (see paper).
Note (3): pcont is the probability that the star belongs to the background
population (see paper).
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Acknowledgements:
Siegfried Roeser, roeser(at)ari.uni-heidelberg.de
(End) Siegfried Roeser [Heidelberg], Patricia Vannier [CDS] 18-Jun-2019