J/A+A/638/A103 Central stars of planetary nebulae in Gaia DR2 (Chornay+, 2020)
Searching for central stars of planetary nebulae in Gaia DR2.
Chornay N., Walton N.A.
<Astron. Astrophys. 638, A103 (2020)>
=2020A&A...638A.103C 2020A&A...638A.103C (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Photometry ; Optical ;
Parallaxes, trigonometric
Keywords: astrometry - methods: statistical - parallaxes -
planetary nebulae: general
Abstract:
Accurate distance measurements are fundamental to the study of
planetary nebulae (PNe) but they have long been elusive. The most
accurate and model-independent distance measurements for galactic PNe
come from the trigonometric parallaxes of their central stars, which
were only available for a few tens of objects prior to the Gaia
mission.
The accurate identification of PN central stars (CSPNe) in the Gaia
source catalogues is a critical prerequisite for leveraging the
unprecedented scope and precision of the trigonometric parallaxes
measured by Gaia. Our aim is to build a complete sample of PN central
star detections with minimal contamination.
We developed and applied an automated technique based on the
likelihood ratio method to match candidate central stars in Gaia Data
Release 2 (DR2) to known PNe in the Hong Kong/AAO/Strasbourg Hα
(HASH) PN catalogue (Parker et al. 2016, 2016JPhCS.728c2008P 2016JPhCS.728c2008P), taking
into account the BP-RP colours of the Gaia sources as well as their
positional offsets from the nebula centres. These parameter
distributions for both true central stars and background sources were
inferred directly from the data.
We present a catalogue of over 1000 Gaia sources that our method has
automatically identified as likely PN central stars. We demonstrate
how the best matches enable us to trace nebula and central star
evolution and to validate existing statistical distance scales, and we
discuss the prospects for further refinement of the matching based on
additional data. We also compare the accuracy of our catalogue to that
of previous works.
Description:
The full best matches catalogue (Table B.1) is given, containing the
highest reliability matches from Gaia DR2 for all true, likely, and
possible PNe in HASH, for which the reliability is at least 0.2 (our
threshold for a possible match). The catalogue contains, for each PN,
the PN G identifier and name, the Gaia DR2 source ID for the single
best match for that PN, and the reliability of that match determined
by our algorithm. The reliability should be used as a filter to limit
analysis to high confidence matches (e.g. reliability >0.8), with the
particular threshold being dependent on the application. In addition
the table contains selected columns from the Gaia catalogue and from
HASH are that are particularly relevant to the matching and to the
science results presented in this work. From Gaia we include the
position, colour, magnitude, and parallax of the best matching
sources, as well as a derived quantity indicating the astrometric
goodness of fit. From HASH we include PN positions and radii, and
their confirmation status (confirmed, likely, or possible PN). We also
include the separation between the PN and Gaia source positions.
Finally, for convenience, we include cross-match flags with relevant
previous works.
It is important to treat the matches that we provide probabilistically
and appropriately in context. There is a great deal of additional
information not used in our matching, such as source magnitude and
parallax, that can help to disambiguate uncertain cases. For example,
if a candidate source has a precise parallax that strongly disagrees
with other reliable distance measures or leads to an implausible
physical nebula size, that adds weight to the source in fact being
coincidental, especially in the absence of strong evidence from other
non-positional features such as colour. These caveats are, of course,
not unique to our work, though ours is the first to attempt to
quantify the uncertainties involved.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 295 1935 Catalogue of best matches
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See also:
I/345 : Gaia DR2 (Gaia Collaboration,, 2018)
http://202.189.117.101:8999/gpne/index.php : HASH Home Page
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- PNG PN G identifier (from HASH) (1)
13- 43 A31 --- Name ? PN name (from HASH)
45- 63 I19 --- Source Gaia DR2 source identifier
65- 85 F21.17 deg RAdeg Gaia Right ascension (ICRS) at Ep=2015.5
87-108 F22.18 deg DEdeg Gaia Declination (ICRS) at Ep=2015.5
110-128 F19.17 --- Rel [0/1] Reliability of match (2)
130-151 F22.19 arcsec Sep Separation between Gaia and PN position
153-174 F22.19 mag BP-RP ? Gaia (BP-RP) colour
176-193 F18.15 mag Gmag Gaia G magnitude
195-217 F23.19 mas plx ? Gaia parallax
219-238 F20.18 mas e_plx ? Gaia parallax error
240-259 F20.16 --- RUWE Gaia renormalised unit weight error
261-269 F9.5 deg pnRAdeg PN Right ascension (ICRS, J2000) (from HASH)
271-279 F9.5 deg pnDEdeg PN Declination (ICRS, J2000) (from HASH)
281-287 F7.2 arcsec pnRad ? PN radius (from HASH) (3)
289 A1 --- pnStat [TLP] PN confirmation status (from HASH) (4)
291-295 I5 --- XMatch Cross-match flags (5)
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Note (1): Formatted as LLL.l+BB.b with a couple of exceptions. Identifiers taken
from HASH and may differ slightly from galactic coordinates of PN.
Note (2): Probability of match being correct, determined by our method using
source colour and position. We consider candidate sources with
reliability > 0.8 to be good matches and those with reliability
between 0.2 and 0.8 to be uncertain. Only the single highest
reliability candidate match is included for each PN, and candidates
with reliability below 0.2 are excluded altogether.
Note (3): PN radii are taken to be half of the Major Diameter in HASH.
Note (4): PN confirmation status (from HASH):
T = True PN
L = Likely PN
P = Possible PN
Note (5): Numeric code indicating cross matches with previous works. From high
to low order digit (left to right in the code), these works are:
X0000 = List of binary PN central stars compiled by David Jones
http://www.drdjones.net/bcspn/
0X000 = Catalogue of PNe in Stanghellini & Haywood
(2010ApJ...714.1096S 2010ApJ...714.1096S, Cat. J/ApJ/714/1096/table1, SH10 below)
00X00 = Catalogue of CSPNe in Gaia DR2 from Stanghellini et al.
(2020ApJ...889...21S 2020ApJ...889...21S, S+20 below)
000X0 = Catalogue of CSPNe in Gaia DR2 from Gonzalez-Santamaria et
al. (2019A&A...630A.150G 2019A&A...630A.150G, Cat. J/A+A/630/A150, GS19 below)
0000X = Catalogue of CSPNe in Gaia DR2 from Kimeswenger & Barria
(2018A&A...616L...2K 2018A&A...616L...2K, Cat. J/A+A/616/L2, KB18 below)
The digit values represent the following:
0 = PN not included in previous work.
1 = Same Gaia DR2 source match (KB18, GS19, S+20 only) / included
in work (SH10) / known or suspected binary CSPN (Jones).
2 = Different or rejected (reliability <0.2) match (KB18, GS19,
S+20 only).
For example, 10210 indicates a binary, disagreement with the match of
S+20, and agreement with the match of GS19. The PN is not included in
SH10 or KB18. As the code is an integer, leading zeros are suppressed
(e.g. 00010 -> 10).
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Acknowledgements:
Nicholas Chornay, njc89(at)cam.ac.uk
(End) Patricia Vannier [CDS] 06-May-2020