J/AJ/150/129 Swift UVOT stars survey. II. RR Lyrae in M3 and M15 (Siegel+, 2015)
The Swift UVOT stars survey. II. RR Lyrae stars in M3 and M15.
Siegel M.H., Porterfield B.L., Balzer B.G., Hagen L.M.Z.
<Astron. J., 150, 129 (2015)>
=2015AJ....150..129S 2015AJ....150..129S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, variable ; Photometry, ultraviolet
Keywords: globular clusters: individual: (M3,M15) - stars: variables: RR Lyrae -
ultraviolet: stars
Abstract:
We present the first results of a Near-UltraViolet (NUV) survey of RR
Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the
Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae
stars have large amplitudes in the far- and near-ultraviolet. We have
used UVOT's unique wide-field NUV imaging capability to perform the
first systematic NUV survey of variable stars in the Galactic globular
clusters M3 and M15. We identify 280 variable stars, comprised of 275
RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis
star, and 1 possible long-period or irregular variable. Only two of
these are new discoveries. We compare our results to previous
investigations and find excellent agreement in the periods with
significantly larger amplitudes in the NUV. We map out, for the first
time, an NUV Bailey diagram from globular clusters, showing the usual
loci for fundamental mode RRab and first overtone RRc pulsators. We
show the unique sensitivity of NUV photometry to both the temperatures
and the surface gravities of RR Lyrae stars. Finally, we show evidence
of an NUV period-metallicity-luminosity relationship. Future
investigations will further examine the dependence of NUV pulsation
parameters on metallicity and Oosterhoff classification.
Description:
The data presented in this analysis are entirely from the Ultraviolet
Optical Telescope (UVOT) on board the Swift mission. UVOT is a
modified Richey-Chretien 30cm telescope that has a wide (17'*17')
field of view and a microchannel plate intensified CCD operating in
photon counting mode. The instrument is equipped with a filter wheel
that includes a clear white filter; u, b, and v optical filters; uvw1,
uvm2, and uvw2 ultraviolet filters; a magnifier; two grisms; and a
blocked filter.
Our light curves are derived from observations taken with UVOT's uvm2
filter, which has a central wavelength of 2246Å and a red leak from
optical light of less than 0.19%. M3 was observed on 2011 August 31 as
part of a Swift team fill-in program. It was then observed 2012 March
11 through 2012 May 31 approximately every 4-8 days as part of MHS's
team fill-in program, then again from 2013 April 4 to 2014 March 29 as
part of MHS's approved Guest Investigator program. M15 was observed
from 2011 May 18 to August 22 as a Target Of Opportunity, every four
days from 2013 April 11 to 2014 March 31 as part of MHS's approved
Guest Investigator program, and then again on 2014 October 16 as a
team fill-in.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 66 219 Parameters of variable stars in M3
table3.dat 66 86 Parameters of variable stars in M15
table4.dat 31 17924 Photometry of variable stars in M3
table5.dat 31 4037 Photometry of variable stars in M15
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See also:
VII/202 : Globular Clusters in the Milky Way (Harris, 1997)
J/AJ/135/1459 : Period of M15 variable stars (Corwin+, 2008)
J/ApJ/670/379 : UV photometry of M15 (Dieball+, 2007)
J/MNRAS/372/1657 : BVI(c) light curves of variables in M3 (Benko+, 2006)
J/AJ/129/1596 : BVI photometric variability survey of M3 (Hartman+, 2005)
J/AJ/129/267 : RR Lyrae variables in NGC 5272 (Cacciari+, 2005)
J/AcA/50/221 : Astrometry of variable stars in M3 (Bakos+, 2000)
J/AJ/110/704 : RR Lyrae Variables in M15 (Silbermann+ 1995)
J/AJ/108/1786 : Blue stragglers and variables in M3 (Guhathakurta+, 1994)
J/AJ/106/154 : HST Observations in inner region of M15 (Ferraro+ 1993)
Byte-by-byte Description of file: table[23].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name Stellar identifier (G1)
5 A1 --- f_Name [*] Star has a SHARP value greater than 0.5 (G2)
7- 8 I2 h RAh Hour of Right Ascension (J2000)
10- 11 I2 min RAm Minute of Right Ascension (J2000)
13- 17 F5.2 s RAs Second of Right Ascension (J2000)
19 A1 --- DE- Sign of the Declination (J2000)
20- 21 I2 deg DEd Degree of Declination (J2000)
23- 24 I2 arcmin DEm Arcminute of Declination (J2000)
26- 29 F4.1 arcsec DEs Arcsecond of Declination (J2000)
31- 41 F11.7 d Per [0.07163/253]? Period
43- 48 F6.3 mag [0/21] Mean Swift/UVOT UVM2 band magnitude
50- 54 F5.3 mag Amp [0.2/2.8]? Amplitude of the Swift/UVOT UVM2
band magnitude
56- 60 F5.2 --- Var [0.22/25.96] Variability index from DAOPHOT
62- 66 F5.2 --- SHARP [-0.4/2.1] The SHARP parameter from DAOPHOT
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Byte-by-byte Description of file: table[45].dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name Stellar identifier (G1)
5 A1 --- f_Name [*] Star has a SHARP value greater than 0.5 (G2)
7- 18 F12.4 d JD Julian Date of observation
20- 25 F6.3 mag UVM2 [13.9/22] Swift/UVOT UVM2 band magnitude
27- 31 F5.3 mag e_UVM2 [0.016/0.398] Uncertainty in UVM2
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Global Notes:
Note (G1): Taken from Clement et al. (2001AJ....122.2587C 2001AJ....122.2587C). Where we have
identified new variable stars, we have added new identification numbers
sequential to Clement et al. (2001AJ....122.2587C 2001AJ....122.2587C).
In Table 2, V204 (associated with NGC 5272 390 in SIMBAD) is
very likely a misprint for NGC 5272 1390R; note added by CDS.
Note (G2): These are stars that are mostly in the core of M3 or M15, identified
as potential variable stars from the catalog of Clement et al.
(2001AJ....122.2587C 2001AJ....122.2587C). They are likely blends, with concomitant elevated
magnitudes and dampened pulsational amplitudes.
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History:
From electronic version of the journal
References:
Siegel et al., Paper I, 2014AJ....148..131S 2014AJ....148..131S
Siegel et al., Paper III, 2019AJ....158...35S 2019AJ....158...35S
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 04-Nov-2015