J/ApJ/941/49 SPYGLASS. II. Cepheus Far North candidate members (Kerr+, 2022)
SPYGLASS.
II. The multigenerational and multiorigin star formation history of
Cepheus Far North.
Kerr R., Kraus A.L., Murphy S.J., Krolikowski D.M., Offner S.S.R.,
Tofflemire B.M., Rizzuto A.C.
<Astrophys. J., 941, 49 (2022)>
=2022ApJ...941...49K 2022ApJ...941...49K
ADC_Keywords: YSOs ; Associations, stellar ; Spectra, optical ;
Photometry ; Radial velocities ; Equivalent widths ; Magnitudes ;
Parallaxes, trigonometric ; Binaries, spectroscopic ;
Stars, pre-main sequence
Keywords: Stellar associations ; Stellar ages ; Star formation ;
Pre-main sequence stars
Abstract:
Young stellar populations provide a record of past star formation, and
by establishing their members' dynamics and ages, it is possible to
reconstruct the full history of star formation events. Gaia has
greatly expanded the number of accessible stellar populations, with
one of the most notable recently discovered associations being Cepheus
Far North (CFN), a population containing hundreds of members spanning
over 100pc. With its proximity (d≲200pc), apparent substructure, and
relatively small population, CFN represents a manageable population to
study in depth, with enough evidence of internal complexity to produce
a compelling star formation story. Using Gaia astrometry and
photometry combined with additional spectroscopic observations, we
identify over 500 candidate CFN members spread across seven subgroups.
Combining ages from isochrones, asteroseismology, dynamics, and
lithium depletion, we produce well-constrained ages for all seven
subgroups, revealing a largely continuous 10Myr star formation history
in the association. By tracing back the present-day populations to the
time of their formation, we identify two spatially and dynamically
distinct nodes in which stars form, one associated with β Cephei,
which shows mostly co-spatial formation, and one associated with EE
Draconis with a more dispersed star formation history. This detailed
view of star formation demonstrates the complexity of the star
formation process, even in the smallest of regions.
Description:
We employ observations from two different spectrographs to obtain
improved radial velocity measurements.
Most observations used the TS23 configuration of the Robert G. Tull
Coude spectrograph at the McDonald Observatory's 2.7m Harlan J. Smith
Telescope (HJST), which provides high-resolution spectra with R=60000
for a spectral range between 3400 and 10900Å. Our observations
spanned two programs. The first program targeted stars with Gmag<12 and
a clustering proximity of D>0.25, while the second observed a broader
selection (D>0.05) of later-type stars on the pre-main sequence with
magnitudes 12<Gmag<14, a section of the CMD that reliably produces
high-quality RV measurements alongside clear spectral youth indicators
In total, 97 spectra were taken over the course of 14 nights covering
94 targets, with a few duplicate observations in cases where an
initial observation was made under poor conditions. Our exposure times
ranged from 5 to 30 minutes depending on the stellar magnitude, aiming
for signal-to-noise ratios of at least 30 around the Li 6708Å line,
which enables both radial velocity measurements with sub-km/s and the
robust detection and measurement of Li equivalent widths.
The remaining observations used the Network of Robotic Echelle
Spectrographs (NRES) spectrographs at the 1m nodes of the Las Cumbres
Observatory (LCO) network, which provide high-resolution spectra with
R=53000 for a spectral range between 3800 and 8600Å. These
observations primarily targeted brighter targets at lower D values not
reached during the first allocation at the HJST. Exposure times ranged
from 8 minutes for the brightest targets to 30 minutes for the
faintest. Due to the near complete spectral coverage of NRES within
its advertised wavelength range, Hα was covered in all
observations at the LCO, as was Hβ.
A total of 19 targets were observed using NRES, spread between the
Wise Observatory (TLV) and McDonald Observatory (ELP) nodes.
See Section 3.2.
We add to our observations radial velocities from Gaia DR3 and
additional sources from SIMBAD and Vizier.
See section 3.1.
Objects:
---------------------------------------------------------------------
RA (ICRS) DE Designation(s)
---------------------------------------------------------------------
21 12 00 +75 00 Cepheus Far North = NAME Cepheus Far North
---------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 105 169 *Spectroscopic properties acquired for stars in
Cepheus Far North (CFN) association
table2.dat 79 549 All stars identified as credible candidate members
of the Cepheus Far North association
table6.dat 56 163 *Catalog of binaries in CFN
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Note on table1.dat: Three stars failed the ΣPmem<1 cut but are included
in Table 1 for HJST and LCO observation completeness.
See Section 4.4.
Note on table6.dat: In Table 6 we provide a complete catalog of binary and
multiple systems identified in Cepheus Far North (CFN), covering all
objects within 10000au of each star in the plane of the sky at the
star's distance, provided that they have parallaxes within 20% and
proper motions within 5km/s. When other CFN members were included in
the search radius around a star, the results of a search were only
recorded if the star being searched was brighter than all other CFN
members. This choice avoids duplicates in the list and focuses the
search around the primary, which is typically more central in the
system. All systems are assigned a system ID, which tracks the parent
system of each component. Our resulting catalog contains 163 stars
associated with a binary or multiple system, including 21 stars not in
our candidate member catalog, likely left out due to their high
internal velocity produced from interaction with the companion.
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See also:
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
V/136 : Teff and metallicities for Tycho-2 stars (Ammons+, 2006)
III/254 : 2nd Cat. Radial Velocities with Astrometric Data (Kharchenko+, 2007)
II/328 : AllWISE Data Release (Cutri+ 2013)
I/349 : StarHorse, Gaia DR2 photo-astrometric distances (Anders+, 2019)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/289/101 : Orion OB1 association. I. (Brown+, 1994)
J/ApJ/469/355 : Teff, B-V and BC relation (Flower, 1996)
J/AJ/117/354 : OB associations from Hipparcos (de Zeeuw+, 1999)
J/AJ/124/1670 : Post-T Tauri Stars in Sco-Cen Association (Mamajek+, 2002)
J/AN/328/889 : Mean Radial Velocities of open clusters (Kharchenko+, 2007)
J/A+A/508/833 : SACY III. Li abundances (da Silva+, 2009)
J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)
J/ApJ/731/8 : Multiple star formation in Taurus-Auriga (Kraus+, 2011)
J/AJ/147/146 : Spectroscopy of Tuc-Hor candidate members (Kraus+, 2014)
J/MNRAS/454/593 : Young moving groups in solar neighbourhood (Bell+, 2015)
J/A+A/584/A67 : IRDC18223 images (Beuther+, 2015)
J/A+A/575/A120 : DANCe study of M35 (NGC 2168) (Bouy+, 2015)
J/MNRAS/450/2764 : Spectroscopic survey of Kepler stars. I. (Niemczura+, 2015)
J/MNRAS/448/2737 : New PMS K/M Stars in Upper Scorpius (Rizzuto+, 2015)
J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)
J/AJ/153/128 : WOCS. LXXV. Hyades&Praesepe lithium data (Cummings+, 2017)
J/ApJ/846/144 : Virial analysis of the dense cores in Orion A (Kirk+, 2017)
J/ApJ/838/150 : The Taurus-Auriga ecosystem. I. (Kraus+, 2017)
J/AJ/153/257 : Comoving stars in Gaia DR1 (Oh+, 2017)
J/AJ/154/69 : ACRONYM II. β Pictoris Moving Group (Shkolnik+, 2017)
J/A+A/612/A96 : Sp. survey of youngest field stars II (Frasca+, 2018)
J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)
J/A+A/620/A172 : Solar neighbourhood young stars 3D mapping (Zari+, 2018)
J/AJ/158/93 : Regression of stellar Teff in GaiaDR2 (Bai+, 2019)
J/A+A/626/A17 : Young population in Vela-Puppis (Cantat-Gaudin+, 2019)
J/AJ/158/122 : Local structure & SFH of the MW (Kounkel+, 2019)
J/ApJ/870/32 : Kinematics in young Cl* & associations (Kuhn+, 2019)
J/A+A/625/A135 : Gal. interstellar dust Gaia-2MASS 3D maps (Lallement+, 2019)
J/A+A/637/A43 : Membership in the Cepheus association (Klutsch+, 2020)
J/A+A/642/A179 : beta Pic moving group RV of 81 stars (Miret-Roig+, 2020)
J/AJ/159/273 : Taurus members & nonmembers with K2 data (Rebull+, 2020)
J/ApJ/898/27 : Ages For Field LowEr-mass Stars (Stanford-Moore+, 2020)
J/ApJ/917/23 : SPYGLASS. I. Mapping young stellar structures (Kerr+, 2021)
J/AJ/162/110 : Gaia EDR3 census of Taurus-Auriga (Krolikowski+, 2021)
J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)
J/MNRAS/505/5164 : The Gaia view of the Cepheus flare (Szilagyi+, 2021)
J/AJ/164/215 : Candidate members of Cep-Her, RSG-5 and CH-2 (Bouma+, 2022)
J/ApJ/933/77 : Teff & luminosity of Gaia EDR3 Serpens members (Zhou+, 2022)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaEDR3 Gaia EDR3 identifier
21- 28 F8.4 deg RAdeg Gaia EDR3 Right Ascension (ICRS) at
Epoch=2016.0
30- 36 F7.4 deg DEdeg Gaia EDR3 Declination (ICRS) at Epoch=2016.0
38- 43 F6.2 km/s RV [-64.59/117.4] Radial velocity
45- 49 F5.2 km/s e_RV [0.02/23] Uncertainty in RV
51- 71 A21 --- r_RV Source of RV (1)
73- 77 F5.3 0.1nm EWLi [0/0.7]? Equivalent width, Li (2)
79- 83 F5.3 0.1nm e_EWLi [0/0.2]? Uncertainty in EWLi (2)
85- 89 F5.2 0.1nm EWHb [0/27.3]? Equivalent width, Hβ (2)
91- 97 F7.2 0.1nm e_EWHb [0/1120]? Uncertainty in EWHb (2)
99-105 A7 --- r_EW Spectrum Source (3)
--------------------------------------------------------------------------------
Note (1): RV references as follows:
HJST = This work: Tull Coude spectrograph at the 2.7m Harlan
J. Smith Telescope, at McDonald Observatory
(82 occurences)
I/355/gaiadr3 = Gaia DR3 (2022yCat.1355....0G 2022yCat.1355....0G), Cat. I/355
(66 occurences)
LCO-TLV = This work: NRES spectrograph on 1m telescope at
Wise Observatory (9 occurences)
LCO-ELP = This work: NRES spectrograph on 1m telescope at
McDonald Observatory (5 occurences)
III/252/table8 = 2006PAZh...32..844G 2006PAZh...32..844G , Cat. III/252 (3 occurences)
III/254/crvad2 = 2007AN....328..889K 2007AN....328..889K , Cat. III/254 (2 occurences)
J/A+A/612/A96/tablea1 = 2018A&A...612A..96F 2018A&A...612A..96F , Cat J/A+A/612/A96 (1 occurence)
J/AZh/83/821/osaca = 2006AZh....83..821B 2006AZh....83..821B , Cat. J/AZh/83/821 (1 occurence)
Note (2): For equivalent widths, null (blank) values correspond to a lack of a
spectrum; values of "0.00" correspond to non-detections.
Note (3): Spectrum source as follows:
HJST = Tull Coude spectrograph at the 2.7m Harlan J. Smith
Telescope, at McDonald Observatory (94 occurences)
LCO-TLV = NRES spectrograph on 1m telescope at Wise Observatory
(12 occurences)
LCO-ELP = NRES spectrograph on 1m telescope at McDonald Observatory
(7 occurences)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaEDR3 Gaia EDR3 identifier
21- 21 I1 --- SG [1/7] ID of the subgroup the star is
assigned to (see Tables 3 and 4)
23- 30 F8.4 deg RAdeg Gaia EDR3 Right Ascension (ICRS) at
Epoch=2016.0
32- 38 F7.4 deg DEdeg Gaia EDR3 Declination (ICRS) at Epoch=2016.0
40- 44 F5.2 mag Gmag [6.4/21] Observed Gaia EDR3 G-band magnitude
46- 50 F5.2 mag BP-RP [-0.2/4.34]? Observed Gaia EDR3 BP-RP color
52- 55 F4.2 mas Plx [3.92/7.83] Gaia EDR3 parallax
57- 60 F4.2 Msun Mass [0.09/3.84] Estimated stellar mass
62- 62 I1 --- Disk Presence of a circumstellar disk?
64- 67 F4.2 --- D [0.05/1.0] Clustering proximity parameter (1)
69- 69 I1 --- A Astrometric quality cut from SPYGLASS-I
(1=pass; 0=fail) (2)
71- 71 I1 --- P Photometric quality cut from SPYGLASS-I (3)
73- 74 I2 --- V Velocity membership cuts (4)
76- 76 I1 --- PY Photometric membership calculation (5)
78- 79 I2 --- F Notable features (6)
--------------------------------------------------------------------------------
Note (1): The clustering proximity parameter, D (previously referred to as
"strength" in SPYGLASS-I), between zero and one, where D = 0 corresponds
to the largest d10 (the distance to the 10th nearest neighbor) for a
photometrically young candidate, and D = 1 corresponds to the smallest.
D behaves similarly to the cube root of density, as it has an inverse
relation to the length scale of a cube that contains a fixed number of
stars.
Note (2): The boolean solution to the Astrometric quality cut from
SPYGLASS-I, which is based on the unit weight error.
Note (3): The boolean solution to the Photometric quality cut from
SPYGLASS-I, which is based on the BP/RP flux excess factor.
1 passes, 0 fails.
Note (4): A flag to represent the results of our velocity membership cuts.
1 passes, -1 fails, and 0 has no RV.
Note (5): A flag to represent our photometric membership calculation. A
value of 1 marks stars with ΣPmem greater than 10% of the
total, which contains 90% of genuine members and excludes most outliers,
and 0 has photometry that is neither conclusively non-young nor likely
young. Stars with failed photometric flags (-1) are not included in this
table.
Note (6): A flag for other notable features. The flags are added in cases
where multiple criteria are true; for example, flag 6 indicates both
flag 2 and 4.
1 = that the star has a resolved companion within 10000 AU in the plane of
the sky;
2 = a bad broadening function solution;
4 = a bimodal line profile likely indicative of spectroscopic binarity;
8 = an RUWE>1.2, indicating likely unresolved binarity;
16 = that the RV recorded was ambiguously attributed to two components of a
binary pair.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaEDR3 Gaia EDR3 identifier
21- 22 I2 --- Sys [0/78] System ID (1)
24- 28 I5 AU Sep [0/10113] Separation (2)
30- 37 F8.4 deg RAdeg Gaia EDR3 Right Ascension (ICRS) at Epoch=2016.0
39- 45 F7.4 deg DEdeg Gaia EDR3 Declination (ICRS) at Epoch=2016.0
47- 51 F5.2 mag Gmag [6.5/20.2] Observed Gaia EDR3 G-band magnitude
53- 56 F4.2 mas Plx [4.1/7.8] Gaia EDR3 parallax
--------------------------------------------------------------------------------
Note (1): Objects identified as members of the same system are given the same
system ID.
Note (2): Separation at the distance of the primary relative to the primary.
Primaries have a separation of zero.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
References:
Kerr et al. SPYGLASS. I. 2021ApJ...917...23K 2021ApJ...917...23K Cat. J/ApJ/917/23
Kerr et al. SPYGLASS. II. 2022ApJ...941...49K 2022ApJ...941...49K This catalog
Kerr et al. SPYGLASS. III. 2022ApJ...941..143K 2022ApJ...941..143K
Kerr et al. SPYGLASS. IV. 2023ApJ...954..134K 2023ApJ...954..134K
Kerr et al. SPYGLASS. V. 2024ApJ...975...99K 2024ApJ...975...99K
Kerr et al. SPYGLASS. VI. 2025ApJ...985..111K 2025ApJ...985..111K
(End) Prepared by [AAS], Katia van der Woerd [CDS] 06-Nov-2024