J/MNRAS/488/3238 Search for PN candidates with machine learning (Akras+, 2019)
Compact planetary nebulae:
improved IR diagnostic criteria based on classification tree modelling.
Akras S., Guzman-Ramirez L., Goncalves D.R.
<Mon. Not. R. Astron. Soc., 488, 3238-3250 (2019)>
=2019MNRAS.488.3238A 2019MNRAS.488.3238A (SIMBAD/NED BibCode)
ADC_Keywords: Planetary nebulae ; Photometry, infrared ; Positional data
Keywords: methods: data analysis - methods: statistical - catalogues -
surveys - (ISM:) planetary nebulae: general
Abstract:
Planetary nebulae (PNe) are strong Hα line emitters and a lot of
new PNe discoveries have been made by the SuperCOSMOS AAO/UKST
Hα Survey (SHS) and the Isaac Newton Telescope Photometric
Hα Survey (IPHAS). However, their resulting list of candidates
turned out to be heavily contaminated from Hα-line mimics like
young stellar objects (YSOs) and/or HII regions. The aim of this work
is to find new infrared criteria that can better distinguish compact
PNe from their mimics using a machine learning approach and the
photometric data from the Two-Micron All-Sky Survey and Wide-field
Infrared Survey Explorer. Three classification tree models have been
developed with the following colour criteria: W1-W4≥7.87 and
J-H<1.10; H-W2≥2.24 and J-H<0.50; and Ks-W3≥6.42 and J-H<1.31
providing a list of candidates, characterized by a high probability to
be genuine PNe. The contamination of this list of candidates from
Hα mimics is low but not negligible. By applying these criteria
to the IPHAS list of PN candidates and the entire IPHAS and VPHAS+ DR2
catalogues, we find 141 sources, from which 92 are known PNe, 39 are
new very likely compact PNe (without an available classification or
uncertain) and 10 are classified as HII regions, Wolf-Rayet stars,
AeBe stars, and YSOs. The occurrence of false-positive identifications
in this technique is between 10 and 15 per cent.
Description:
A machine learning technique was devised to search for PN candidates
in the IPHAS and VPHAS+ photometric catalogues. For this study, the
2MASS and AllWISE photometric data were combined with the
classification tree algorithm in order to find suitable infrared
criteria robust enough to distinguish PNe from other classes of
Hα emitters.
Three different classification tree models were found that identify
PNe in the best possible way: W1-W4≥7.87 and J-H<1.10 (M1);
H-W2≥2.24 and J-H<0.50 (M2); and Ks-W3≥6.42 and J-H<1.31 (M3).
Before applying these criteria to the IPHAS and VPHAS+ catalogues, the
distribution of genuine PNe from the HASH catalogue in the IPHAS
(r'-Hα) versus (r'-i') DCCD was explored for different angular
radii up to 8arcsec. PNe with smaller angular sizes have higher
r'-Hα colour index and they belong to zone 1.
The application of our criteria to the list of IPHAS PNe candidates
(Viironen et al. 2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291) provided a
list of 99 sources, from which 81 are genuine PNe (82 per cent) and 11
are likely compact PNe (Table A1). Repeating the same technique for
the entire IPHAS DR2 catalogue, 21 new candidates, not included in
Viironen's list, were recovered and seven of them turned out to be
known PNe (33 per cent) and 13 likely compact PNe (Table A2). Finally,
21 VPHAS+ sources were also found to pass our criteria and only four
of them are known PNe, while 15 of them are likely compact PNe (Table
A3).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 50 99 List of known and candidates PNe that satisfy
our IR criteria obtained from Viironen et al.
(2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291)
tablea2.dat 52 21 List of known and candidates PNe that satisfy
our IR criteria obtained from the IPHAS DR2
catalogue
tablea3.dat 50 21 List of known and candidates PNe that satisfy
our IR criteria obtained from the VPHAS+ DR2
catalogue
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See also:
J/A+A/504/291 : Candidate Planetary Nebulae in IPHAS catalog (Viironen+, 2009)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 35 A11 --- SClass Simbad class (G1)
37 A1 --- f_SClass [ab] Flag on Sclass (1)
39 A1 --- Mod1 [yn] Object classified as PNe by Model 1 (2)
41 A1 --- Mod2 [yn] Object classified as PNe by Model 2 (3)
43 A1 --- Mod3 [yn] Object classified as PNe by Model 3 (4)
45- 50 A6 --- Zone Zone (1 or 2) defined by Viironen et al.
(2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291)
(G2)
--------------------------------------------------------------------------------
Note (1): Flag as follows:
a = No classification is provided for this sources by Viironen et al.
(2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291)
b = Not a SySt according to the criteria from Akras et al.
(2019MNRAS.483.5077A 2019MNRAS.483.5077A, Cat. J/MNRAS/483/5077)
Note (2): Model 1 uses W1-W4≥7.87 and J-H<1.10 to distinguish PNe.
91/99 objects classified as PNe.
Note (3): Model 2 uses H-W2≥2.24 and J-H<0.503 to distinguish PNe.
43/99 objects classified as PNe.
Note (4): Model 3 uses J-H<1.31 and Ks-W3≥6.42 to distinguish PNe.
89/99 objects classified as PNe.
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Byte-by-byte Description of file: tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 35 A11 --- SClass Simbad class (G1)
37 A1 --- f_SClass [a] Flag on Sclass (1)
39 A1 --- Mod1 [yn] Object classified as PNe by Model 1 (2)
41 A1 --- Mod2 [yn] Object classified as PNe by Model 2 (3)
43 A1 --- Mod3 [yn] Object classified as PNe by Model 3 (4)
45- 50 A6 --- Zone Zone (1 or 2) defined by Viironen et al.
(2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291)
(G2)
52 A1 --- f_Zone Flag on Zone (5)
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Note (1): Flag as follows:
a = It is included in the IPHAS list of SySt candidates (Corradi et al.
2008A&A...480..409C 2008A&A...480..409C, Cat. J/A+A/480/409) but it does not satisfy the
criteria of being a SySt proposed by Akras et al. (2019MNRAS.483.5077A 2019MNRAS.483.5077A,
Cat. J/MNRAS/483/5077).
Note (2): Model 1 uses W1-W4≥7.87 and J-H<1.10 to distinguish PNe.
15/21 objects classified as PNe.
Note (3): Model 2 uses H-W2≥2.24 and J-H<0.503 to distinguish PNe.
5/21 objects classified as PNe.
Note (4): Model 3 uses J-H<1.31 and Ks-W3≥6.42 to distinguish PNe.
16/21 objects classified as PNe.
Note (5): Flag as follows:
a = The 2MASS criterion used by Viironen et al. (2009A&A...504..291V 2009A&A...504..291V,
Cat. J/A+A/504/291) is violated
b = The 2MASS criterion used by Viironen et al. (2009A&A...504..291V 2009A&A...504..291V,
Cat. J/A+A/504/291) is not violated but Hα, r', and/or i' is
saturated
c = The 2MASS criterion used by Viironen et al. (2009A&A...504..291V 2009A&A...504..291V,
Cat. J/A+A/504/291) is not violated, Hα, r', and/or i' are not
saturated; hence, these sources should be included in the list of
Viironen's, except they are located at the borders of the CCDs or they
were not detected at least twice
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 h RAh Right ascension (J2000)
4- 5 I2 min RAm Right ascension (J2000)
7- 11 F5.2 s RAs Right ascension (J2000)
13 A1 --- DE- Declination sign (J2000)
14- 15 I2 deg DEd Declination (J2000)
17- 18 I2 arcmin DEm Declination (J2000)
20- 23 F4.1 arcsec DEs Declination (J2000)
25- 35 A11 --- SClass Simbad class (G1)
37 A1 --- f_SClass [ab] Flag on SClass (1)
39 A1 --- Mod1 [yn] Object classified as PNe by Model 1 (2)
41 A1 --- Mod2 [yn] Object classified as PNe by Model 2 (3)
43 A1 --- Mod3 [yn] Object classified as PNe by Model 3 (4)
45- 50 A6 --- Zone Zone (1 or 2) defined by Viironen et al.
(2009A&A...504..291V 2009A&A...504..291V, Cat. J/A+A/504/291)
(G2)
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Note (1): Flag as follows:
a = Not PN according to Frew et al. (2014MNRAS.440.1080F 2014MNRAS.440.1080F,
Cat. J/MNRAS/440/1080)
b = Not a SySt according to the criteria from Akras et al.
(2019MNRAS.483.5077A 2019MNRAS.483.5077A, Cat. J/MNRAS/483/5077)
Note (2): Model 1 uses W1-W4≥7.87 and J-H<1.10 to distinguish PNe.
9/21 objects classified as PNe.
Note (3): Model 2 uses H-W2≥2.24 and J-H<0.503 to distinguish PNe.
6/21 objects classified as PNe.
Note (4): Model 3 uses J-H<1.31 and Ks-W3≥6.42 to distinguish PNe.
16/21 objects classified as PNe.
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Global Notes:
Note (G1): Abbreviation p PN: possible PN, ELS: emission line star,
SySt: symbiotic star
Note (G2): Zone 1 is defined by r'-Hα>0.25(r'-i')+1.9 and zone 2 is
defined by 0.25(r'-i')+0.87)<r'-Hα<0.25(r'-i')+1.9
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 14-Dec-2022