J/MNRAS/468/931 Orion Nebula Cluster members VRI photometry (Messina+, 2017)
Impact of photometric variability on age and mass determination in young stellar
objects: the case of the Orion Nebula Cluster.
Messina S., Parihar P., Distefano E.
<Mon. Not. R. Astron. Soc., 468, 931-945 (2017)>
=2017MNRAS.468..931M 2017MNRAS.468..931M (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; YSOs ; Photometry, VRI
Keywords: stars: activity - Hertzsprung-Russell and colour-magnitude diagrams -
stars: individual: Orion Nebula Cluster - stars: pre-main-sequence -
stars: rotation
Abstract:
Very young stars, like the Orion Nebula Cluster (ONC) members analysed
in the present study, exhibit photometric variability with a wide
range of amplitudes. Such a prominent variability reflects in the
inferred values of stellar colours and luminosities and, in turn, in
the inferred stellar ages and masses. In this study, we measure the
amplitudes of the photometric variability in V, R and I optical bands
of a sample of 346 ONC members. We use these measurements to
investigate how this variability affects the inferred masses and ages
and whether it alone can account for the age spread among ONC members
reported by earlier studies. We make use of colour-magnitude and
Hertzprung-Russell (HR) diagrams. We find that members that show
periodic and smooth photometric rotational modulation have masses and
ages that are unaffected by variability when theoretical isochrones
and evolutionary mass tracks are used in either colour-magnitude or HR
diagrams. On the other hand, members with periodic but very scattered
photometric rotational modulation and non-periodic members have masses
and ages that are significantly affected. Moreover, using HR diagrams,
we find that the observed I-band photometric variability can take
account of only a fraction (∼50 per cent) of the inferred age
spread, whereas the V-band photometric variability is large enough to
mask any age spread.
Description:
We have been monitoring a sample of 346 members of the ONC in the V, R
and I bands for five consecutive years, from 2002-2003 to
2007-2008. Analysing the multi-band photometric time series, we
detected magnitude and colour variability in all stars and with a wide
range of amplitudes. We measured the magnitude and colour maximum and
minimum values and the amplitude of variation of each star in each
observation season and in the full 5-yr time series.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 58 346 Summary of V-band photometry of ONC members
table2.dat 60 346 Summary of I-band photometry of ONC members
table3.dat 51 346 Summary of V-I photometry of ONC members
table4.dat 87 1620 Summary of slopes and correlation coefficients
of magnitude and color variation among
different photometric bands
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [PMD2009] Star identification number
5- 7 I3 --- Nobs Number of observations
9 I1 --- Nout Number of outliers
11 I1 --- Nseas [0/5] Season number
13- 19 F7.4 mag Vmagmean Average V magnitude
21- 25 F5.3 mag e_Vmagmean rms uncertainty on Vmagmean
27- 31 F5.3 mag sVmagtot Standard deviation computed for the complete
5-yr time series
33- 37 F5.3 mag sVmagseas Average seasonal standard deviation
39- 44 F6.3 mag b_Vmag Faintest V magnitude in the complete time series
46- 51 F6.3 mag B_Vmag Brightest V magnitude in the complete time series
53- 58 F6.4 mag e_Vmag Photometric precision
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [PMD2009] Star identification number
5- 7 I3 --- Nobs Number of observations
9- 10 I2 --- Nout Number of outliers
12 I1 --- Nseas [0/5] Season number
14- 19 F6.3 mag Imagmean Average I magnitude
21- 25 F5.3 mag e_Imagmean rms uncertainty on Imagmean
27- 32 F6.4 mag sImagtot Standard deviation computed for the complete
5-yr time series
34- 39 F6.4 mag sImagseas Average seasonal standard deviation
41- 46 F6.3 mag b_Imag Faintest I magnitude in the complete time series
48- 53 F6.3 mag B_Imag Brightest I magnitude in the complete time series
55- 60 F6.4 mag e_Imag Photometric precision
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [PMD2009] Star identification number
5- 7 I3 --- Nobs Number of observations
9 I1 --- Nout Number of outliers
11 I1 --- Nseas [0/5] Season number
13- 18 F6.3 mag V-Imean Average V-I colour index
20- 24 F5.3 mag e_V-Imean rms uncertainty on V-Imean
26- 28 F3.1 mag sV-Itot Standard deviation computed for the complete
5-yr time series
30- 32 F3.1 mag sV-Iseas Average seasonal standard deviation
34- 38 F5.3 mag b_V-I Faintest V-I colour in the complete time series
40- 45 F6.3 mag B_V-I Brightest V-I colour in the complete time series
47- 51 F5.3 mag e_V-I Photometric precision
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- [PMD2009] Star identification number
5- 9 A5 --- Season Season
11- 22 F12.4 d HJD Mean heliocentric Julian date
24- 25 I2 --- NI Number of observation in I band
27- 28 I2 --- NR Number of observation in R band
30- 31 I2 --- NV Number of observation in V band
33- 38 F6.3 --- bV-VI ?=99.999 Slope for V, V-I
40- 45 F6.3 --- rV-VI ?=99.999 Correlation coefficient for V, V-I
47- 52 F6.3 --- bR-RI ?=99.999 Slope for R, R-I
54- 59 F6.3 --- rR-RI ?=99.999 Correlation coefficient for R, R-I
61- 66 F6.3 --- bV-VR ?=99.999 Slope for V, V-R
68- 73 F6.3 --- rV-VR ?=99.999 Correlation coefficient for V, V-R
75- 80 F6.3 --- bRI-VR ?=99.999 Slope for R-I, V-R
82- 87 F6.3 --- rRI-VR ?=99.999 Correlation coefficient for R-I, V-R
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 04-Dec-2019