J/MNRAS/486/4590 139 high-amplitude variable stars (Contreras+, 2019)
Determining the recurrence time-scale of long-lasting YSO outbursts.
Contreras Pena C., Naylor T., Morrell S.
<Mon. Not. R. Astron. Soc., 486, 4590-4611 (2019)>
=2019MNRAS.486.4590C 2019MNRAS.486.4590C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, pre-main sequence ; Stars, variable ; YSOs ; Optical ;
Magnitudes
Keywords: stars: formation - stars: pre-main-sequence - stars: protostars -
stars: variables: T Tauri, Herbig Ae/Be
Abstract:
We have determined the rate of large accretion events in Class I and
II young stellar objects (YSOs) by comparing the all-sky digitized
photographic plate surveys provided by SuperCOSMOS with the latest
data release from Gaia (DR2). The long mean baseline of 55yr along
with a large sample of Class II YSOs (∼15000) allows us to study
approximately 1 million YSO-years. We find 139 objects with
ΔR≥1mag, most of which are found at amplitudes between 1 and
3mag. The majority of YSOs in this group show irregular variability or
long-lasting fading events, which is best explained as hotspots due to
accretion or by variable extinction. There is a tail of YSOs at
ΔR≥3mag and they seem to represent a different population.
Surprisingly many objects in this group show high-amplitude irregular
variability over time-scales shorter than 10yr, in contrast with the
view that high-amplitude objects always have long outbursts. However,
we find six objects that are consistent with undergoing large,
long-lasting accretion events, three of them previously unknown. This
yields an outburst recurrence time-scale of 112kyr, with a 68 per cent
confidence interval [74-180]kyr. This represents the first robust
determination of the outburst rate in Class II YSOs and shows that
YSOs in their planet-forming stage do in fact undergo large accretion
events, and with time-scales of ∼100000yr. In addition, we find that
outbursts in the Class II stage are ∼10 times less frequent than
during the Class I stage.
Description:
To establish the recurrence rate of accretion related outbursts during
the planet-forming stage, it is important to maximize both the time
baseline and the number of YSOs surveyed (see e.g. Hillenbrand &
Findeisen 2015ApJ...808...68H 2015ApJ...808...68H). In this paper, we achieve both by
comparing the magnitudes of a large sample of Class II YSOs from the
photographic atlases provided by the SuperCOSMOS Sky Survey (hereafter
SSS, Hambly et al. 2001MNRAS.326.1279H 2001MNRAS.326.1279H) with the latest Gaia data
release (DR2) (Gaia Collaboration 2018A&A...616A...1G 2018A&A...616A...1G, Cat. I/345)
We note that the current classification system of eruptive YSOs is a
largely phenomenological one based on photometric and spectroscopic
characteristics, with long-term outbursts falling into the FU Orionis
(FUor) class and short-term, repetitive outbursts classified as EXors.
However, the more recent data show characteristics that have been
difficult to classify into the original subclasses (see e.g. Contreras
Pena et al. 2017MNRAS.465.3039C 2017MNRAS.465.3039C, Cat. J/MNRAS/465/3039). Given this,
during the remainder of the paper, we will not ascribe a class to the
dramatic accretion events that we are searching for, but we will
simply use a physical classification and refer to them as
high-amplitude, long-term accretion events.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 157 139 The 139 high-amplitude variable stars detected
in our analysis
table1.dat 73 15831 Photometry for 139 high-amplitude variable stars
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See also:
I/345 : Gaia DR2 (Gaia Collaboration 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Internal object identifier (VNNN)
6 A1 --- f_ID [*] Flag on ID (1)
8- 9 I2 h RAh Right ascension (J2000)
11- 12 I2 min RAm Right ascension (J2000)
14- 18 F5.2 s RAs Right ascension (J2000)
20 A1 --- DE- Declination sign (J2000)
21- 22 I2 deg DEd Declination (J2000)
24- 25 I2 arcmin DEm Declination (J2000)
27- 31 F5.2 arcsec DEs Declination (J2000)
33- 62 A30 --- SName Simbad name
64- 78 A15 --- Sclass Object type from Simbad
80- 82 F3.1 mag DeltaR Observed R amplitude taking into account only
the SSS and Gaia epochs (2)
84-105 A22 --- LCClass Classification for the behaviour of the light
curve of the YSO
107-133 A27 --- Class Final classification of the light curve
135-139 A5 --- r_Class References for Class (3)
141 A1 --- Known [YN] Indicates whether the object is a known
variable star
143 A1 --- SSS [YN] Indicates whether the SSS versus Gaia
variability relates to the known variability
of the source
145-157 A13 --- YSO Source used to classify the YSOs as being in
the Class II stage (4)
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Note (1): Flag as follows:
* = Objects not included in any subsequent analysis
Note (2): Amplitude computed after transforming the Gaia G-band, and SSS B and
I-band magnitudes into R-band magnitudes
Note (3): References as follows:
1 = Aspin et al. 2009AJ....137..431A 2009AJ....137..431A
2 = Barsunova et al. 2015Ap.....58..193B 2015Ap.....58..193B
3 = Carpenter et al. 2001AJ....121.3160C 2001AJ....121.3160C, Cat. J/AJ/121/3160
5 = Connelley & Reipurth 2018ApJ...861..145C 2018ApJ...861..145C
6 = Davies et al. 2018MNRAS.474.5406D 2018MNRAS.474.5406D
7 = Drake et al. 2009ApJ...696..870D 2009ApJ...696..870D, Cat. J/ApJ/696/870
8 = Findeisen et al. 2013ApJ...768...93F 2013ApJ...768...93F
9 = Frasca et al. 2017A&A...602A..33F 2017A&A...602A..33F, Cat. J/A+A/602/A33
10 = Froebrich et al. 2018MNRAS.478.5091F 2018MNRAS.478.5091F, Cat. J/MNRAS/478/5091
11 = Galan et al. 2016MNRAS.455.1282G 2016MNRAS.455.1282G
12 = Garate et al. 2019ApJ...871...53G 2019ApJ...871...53G
13 = Giannini et al. 2016A&A...588A..20G 2016A&A...588A..20G
14 = Hedges et al. 2018MNRAS.476.2968H 2018MNRAS.476.2968H
15 = Hodgkin et al. 2013RSPTA.37120239H 2013RSPTA.37120239H Gaia19avc
16 = Jayasinghe et al. 2018MNRAS.477.3145J 2018MNRAS.477.3145J, Cat. II/366
17 = Klagyivik et al. 2013ApJ...773...54K 2013ApJ...773...54K, Cat. J/ApJ/773/54
18 = Lee & Chen 2007ApJ...657..884L 2007ApJ...657..884L, Cat. J/ApJ/657/884
19 = Ofek al. 2012PASP..124..854O 2012PASP..124..854O, Cat. II/313
20 = Pettersson 1987A&A...171..101P 1987A&A...171..101P
21 = Pojmanski 2002AcA....52..397P 2002AcA....52..397P, Cat. II/264
22 = Principe et al. 2016MNRAS.459.2097P 2016MNRAS.459.2097P
23 = Rice et al. 2015AJ....150..132R 2015AJ....150..132R, Cat. J/AJ/150/132
24 = Rodriguez et al. 2016ApJ...831...74R 2016ApJ...831...74R
25 = Sicilia-Aguilar et al. 2017A&A...607A.127S 2017A&A...607A.127S, Cat. J/A+A/607/A127
26 = Stecklum & Linz 2013prpl.conf2B062S
27 = Wolk et al. 2013ApJ...773..145W 2013ApJ...773..145W
28 = Wozniak et al. 2004AJ....127.2436W 2004AJ....127.2436W, Cat. II/287
29 = Xue et al. 2019MNRAS.482..658X 2019MNRAS.482..658X, Cat. J/MNRAS/482/658
30 = This work
Note (4): Source as follows:
Marton = Marton et al. (2016MNRAS.458.3479M 2016MNRAS.458.3479M) (68/139)
Megeath alpha = Megeath et al. (2012AJ....144..192M 2012AJ....144..192M) (7/139)
Megeath disk = Megeath et al. (2012AJ....144..192M 2012AJ....144..192M) (1/139)
Megeath mag = Megeath et al. (2012AJ....144..192M 2012AJ....144..192M) (2/139)
gut09 = Gutermuth et al. (2009ApJS..184...18G 2009ApJS..184...18G) (7/139)
C2D = Evans et al. (2003PASP..115..965E 2003PASP..115..965E) (13/139)
WISE slt04 = Cutri et al. (2014yCat.2328....0C 2014yCat.2328....0C) (31/139)
2M AAA = Skrutskie et al. (2006AJ....131.1163S 2006AJ....131.1163S) (9/139)
Mystix = MYStIX, Feigelson et al. (2013ApJS..209...26F 2013ApJS..209...26F) (1/139)
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 A4 --- ID Internal object identifier (VNNN)
6- 14 F9.3 d MJD Modified Julian date of the observations
(JD-2400000.5)
16- 20 F5.2 mag rmag R- or r-band magnitude
22 A1 --- Filter [rR] Filter used to obtain the magnitude
24- 37 A14 --- Survey Survey from which the magnitude was extracted
39- 73 A35 --- n_rmag Note on rmag (1)
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Note (1): Note depending on whether the magnitudes are an upper limit or if
these result from transforming between different filters (marked as
approximate in the table)
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 26-Oct-2022