J/MNRAS/504/L17 Mon OB4 a new association in Gaia DR2 (Teixeira+, 2021)
Monoceros OB4 a new association in Gaia DR2.
Teixeira P.S., Alves J., Sicilia-Aguilar A., Hacar A., Scholz A.
<Mon. Not. R. Astron. Soc., 504,L17-L21 (2021)>
=2021MNRAS.504L..17T 2021MNRAS.504L..17T (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; YSOs ; Clusters, open ; Molecular clouds ;
Photometry, G band ; Proper motions ; Positional data ; Extinction
Keywords: stars: pre-main-sequence -
Galaxy: open clusters and associations: Monoceros OB1
Abstract:
We use Gaia DR2 data to survey the classic Monoceros OB1 region and
look for the existence of a dispersed young population, co-moving with
the cloud complex. An analysis of the distribution of proper motions
reveals a 20-30 Myr association of young stars, about 300-400 pc away
from the far side of the Mon OB1 complex, along the same general line
of sight. We characterize the new association, Monoceros OB4, and
estimate it contains between 1400 and 2500 stars, assuming a standard
initial mass function, putting it on par in size with NGC 2264. We
find from the internal proper motions that Mon OB4 is unbound and
expanding. Our results seem to unveil a larger and more complex
Monoceros star formation region, suggesting an elongated arrangement
that seems to be at least 300 x 60 pc.
Description:
In order to reveal the list of candidate members of the new cluster
association Mon OB4, we use a sub-sample of the Gaia DR2 filtered data
which is constrained by galactic coordinates, distance,
parallax/parallax error and error in proper motion (as described in
Section 2, and also Lindegren et al. 2018A&A...616A...2L 2018A&A...616A...2L, Cat. I/345).
Then, we identify the new co-moving group by analysing a density map
in the proper motion phase space. Consequently, we only retained
sources whose proper motion fall within the 3σ contour level of
the ellipse that is centered on the higher density number (count in
bin) of density map. Hereafter, we analysed the co-moving group by
building a density map in the transverse velocity phase space
including transverse velocity along right ascension and declination.
We did the 3σ ellipses constrain centered on the higher density
number. We selected sources that satisfied both proper motion and
transverse velocity criteria simultaneously, in order to minimize
contamination (as see in the table 1 summarizes the kinematic
selection criteria parameters, including the rotation angles for the
proper motion and the transverse velocity). Finally, we obtained as
listed in the table2.dat, 242 candidate members representing the new
co-moving group located at a mean distance of 1182 ± 122 pc just
behind the molecular cloud complex Mon OB1.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 43 242 list of candidate members of the new cluster
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 Gaia DR2 Source ID (GaiaDR2Source_ID)
21- 27 F7.3 deg GLON Galactic longitude (l)
29- 34 F6.3 deg GLAT Galactic latitude (b)
36- 39 I4 pc D Source distance in units of parsec (Dist)
41- 43 F3.1 mag Av Extinction (Av)
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 17-Apr-2024