J/AJ/152/2 Photometry and spectroscopy of NP Per (Lacy+, 2016)
Absolute properties of the pre-main-sequence eclipsing binary star NP Persei.
Lacy C.H.S., Fekel F.C., Pavlovski K., Torres G., Muterspaugh M.W.
<Astron. J., 152, 2-2 (2016)>
=2016AJ....152....2L 2016AJ....152....2L (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, eclipsing ; Radial velocities ; Photometry
Keywords: binaries: eclipsing - binaries: spectroscopic -
stars: fundamental parameters - stars: individual (NP Per)
Abstract:
NP Per is a well-detached, 2.2 day eclipsing binary whose components
are both pre-main-sequence stars that are still contracting toward the
main-sequence phase of evolution. We report extensive photometric and
spectroscopic observations with which we have determined their
properties accurately. Their surface temperatures are quite different:
6420±90K for the larger F5 primary star and 4540±160K for the
smaller K5e star. Their masses and radii are 1.3207±0.0087 solar
masses and 1.372±0.013 solar radii for the primary, and
1.0456±0.0046 solar masses and 1.229±0.013 solar radii for the
secondary. The orbital period is variable over long periods of time. A
comparison of the observations with current stellar evolution models
from MESA indicates that the stars cannot be fit at a single age: the
secondary appears significantly younger than the primary. If the stars
are assumed to be coeval and to have the age of the primary (17Myr),
then the secondary is larger and cooler than predicted by current
models. The Hα spectral line of the secondary component is
completely filled by, presumably, chromospheric emission due to a
magnetic activity cycle.
Description:
From 2011 November through 2014 November, we acquired 56 high-quality
spectra of NP Per with the Tennessee State University 2m Automatic
Spectroscopic Telescope (AST) and a fiber-fed echelle spectrograph at
Fairborn Observatory in southeast Arizona. Of these spectra, 55 were
suitable for radial velocity measurements (see Table1). The detector
for these observations was a Fairchild 486 CCD, having 4096*4096
15µ pixels. While the spectrograms have 48 orders ranging from 3800
to 8260Å, we have used just the orders that cover the wavelength
region from 4920 to 7100Å. We made our observations with a fiber
that produced a spectral resolution of 0.4Å, corresponding to a
resolving power of 15000 at 6000Å. Our spectra have typical
signal-to-noise ratios (S/Ns) of 40 at 6000Å.
We began V-band photometric observations of NP Per with the URSA
WebScope on 2003 December 2. URSA is a 10inch Schmidt-Cassegrain
telescope made by Meade Instruments Corp., equipped with a V-band
filter and a Santa Barbara Instruments Group ST8 CCD camera, housed in
a Technical Innovations RoboDome, all controlled by a Macintosh
computer in a control room under the observing deck of Kimpel Hall on
the University of Arkansas campus at Fayetteville. A larger telescope,
the NFO WebScope, was brought to bear on 2005 February 27. Nearly all
the observations after this date were obtained with the NFO, which is
a robotic 24inch Cassegrain reflector located near Silver City, NM,
USA. Both telescopes used Bessel V filters consisting of 2.0mm of
GG495 and 3.0mm of BG 39. Exposures were 120 seconds long for both
telescopes, and the cadence was typically 150 seconds per image. The
images contained the variable star (TYC 2371-0390-1=BD +31 0729) and 2
comparison stars (TYC 2371-156-1 and TYC 2371-1034-1) of approximately
the same brightness and color as the variable star. The observations
are given in Table6 for the URSA WebScope and in Table7 for the NFO
WebScope.
Dates of eclipses obtained from the literature are given in Table8.
Objects:
--------------------------------------------------------------------
RA (ICRS) DE Designation(s) (Period)
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04 14 57.76 +31 26 44.0 NP Per = TYC 2371-390-1 (P=2.22857242)
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 39 55 Heliocentric radial velocities for NP Per
table4.dat 16 14131 Disentangled spectrum of the primary component
of NP Per
table5.dat 16 14131 Disentangled spectrum of the secondary of NP Per
table6.dat 17 740 V-band differential photometry of NP Per from
the URSA WebScope
table7.dat 17 7126 V-band differential photometry of NP Per from
the NFO WebScope
table8.dat 31 50 Observed dates of minimum light for NP Per
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See also:
J/AJ/147/148 : Spectroscopy and photometry of AP And (Lacy+, 2014)
J/AJ/142/185 : Properties of the eclipsing binary stars HY Vir (Lacy+, 2011)
J/AJ/130/2838 : Velocity and light curves of RW Lac (Lacy+, 2005)
J/A+A/384/145 : Compiled catalog of Per OB2 star forming complex
(Belikov+, 2002)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 F10.4 d HJD [55888/56978] Heliocentric Julian Date (HJD-2400000)
12- 16 F5.3 --- Phase [0/1] Phase in the inner orbit
18- 22 F5.1 km/s HRVA [-77.4/113.5] Star A heliocentric radial velocity
24- 27 F4.1 km/s O-CA [-1.4/1.9] Star A (O-C) residual
29- 34 F6.1 km/s HRVB [-105.9/134.2] Star B heliocentric radial velocity
36- 39 F4.1 km/s O-CB [-3.9/3.5] Star B (O-C) residual
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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- 8 F8.3 0.1nm lambda [5033/6805] Spectrum wavelength (in Å) (1)
10- 16 F7.5 --- Flux [0.464/1.017] Spectrum flux (normalized units) (1)
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Note (1): The primary star (table4) is the hotter, and the secondary star
(table5) is the cooler.
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Byte-by-byte Description of file: table[67].dat
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Bytes Format Units Label Explanations
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1- 11 F11.5 d HJD Heliocentric Julian Date (HJD-2400000) (1)
13- 17 F5.3 mag dVmag [0.772/1.7] The ΔV-band magnitude (2)
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Note (1): The orbital phase can be computed from the equation:
HJD(MinI)=2453386.71481(16)+2.22857242(12)E.
Note (2): The variable star magnitudes were relative to the sum of the fluxes of
the comparison stars (TYC 2371-156-1 and TYC 2371-1034-1).
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1 I1 --- Type [1/2] Eclipse type (1=deep, or 2=shallow eclipse)
3- 12 F10.4 d HJD [18275/56956] Heliocentric Julian Date (HJD-2400000)
14- 19 F6.4 d e_HJD [0.0001/0.03] Uncertainty in HJD of eclipse date
21- 28 F8.5 d O-C [-0.34/0.014] Eclipse O-C residual
30- 31 I2 --- Ref [1/18] Reference (1)
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Note (1): Literature references for eclipses are defined as follows:
1 = Kholopov (1975PZP.....2..241K 1975PZP.....2..241K);
2 = Diethelm R. (1975, BBSAG Bulletin, No. 21 1);
3 = BRNO Contr. N. Copernicus Obs. & Planetarium, No. 31;
4 = Diethelm (1999BBSAG.119....1. 1999BBSAG.119....1.);
5 = Lacy (2006IBVS.5670....1L 2006IBVS.5670....1L);
6 = Lacy (2007IBVS.5764....1L 2007IBVS.5764....1L);
7 = Hubscher & Walter 2007 (Cat. J/other/IBVS/5761);
8 = Agerer F. (2009, BAVM, No. 201);
9 = Diethelm (2009IBVS.5894....1D 2009IBVS.5894....1D);
10 = Diethelm (2010IBVS.5945....1D 2010IBVS.5945....1D);
11 = Lacy (2011IBVS.5972....1L 2011IBVS.5972....1L);
12 = Diethelm (2011IBVS.5960....1D 2011IBVS.5960....1D);
13 = Honkova et al. (2013OEJV..160....1H 2013OEJV..160....1H);
14 = Lacy (2012IBVS.6014....1L 2012IBVS.6014....1L);
15 = Diethelm (2012IBVS.6029....1D 2012IBVS.6029....1D);
16 = Lacy (2013IBVS.6046....1L 2013IBVS.6046....1L);
17 = Lacy (2014IBVS.6098....1L 2014IBVS.6098....1L);
18 = Lacy (2015IBVS.6130....1L 2015IBVS.6130....1L).
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 12-Sep-2016