IDENTIFYING THE YOUNG LOW-MASS STARS WITHIN 25 PC. I. SPECTROSCOPIC OBSERVATIONS

By E. Shkolnik, Michael C. Liu, I. Neill Reid. 2009

143 citations recorded by the source corpus.

We have completed a high-resolution (R ≈ 60,000) optical spectroscopic survey of 185 nearby M dwarfs identified using ROSAT data to select active, young objects with fractional X-ray luminosities comparable to or greater than Pleiades members. Our targets are drawn from the NStars 20 pc census and the Moving-M sample with distances determined from parallaxes or spectrophotometric relations. We limited our sample to 25 pc from the Sun, prior to correcting for pre-main-sequence overluminosity or binarity. Nearly half of the resulting M dwarfs are not present in the Gliese catalog and have no previously published spectral types. We identified 30 spectroscopic binaries (SBs) from the sample, which have strong X-ray emission due to tidal spin-up rather than youth. This is equivalent to a 16% SB fraction, with at most a handful of undiscovered SBs. We estimate upper limits on the age of the remaining M dwarfs using spectroscopic youth indicators such as surface gravity-sensitive indices (CaH and K i). We find that for a sample of field stars with no metallicity measurements, a single CaH gravity index may not be sufficient, as higher metallicities mimic lower gravity. This is demonstrated in a subsample of metal-rich radial velocity (RV) standards, which appear to have low surface gravity as measured by the CaH index, yet show no other evidence of youth. We also use additional youth diagnostics such as lithium absorption and strong Hα emission to set more stringent age limits. Eleven M dwarfs with no Hα emission or absorption are likely old (>400 Myr) and were caught during an X-ray flare. We estimate that our final sample of the 144 youngest and nearest low-mass objects in the field is less than 300 Myr old, with 30% of them being younger than 150 Myr and four very young (⪅10 Myr), representing a generally untapped and well-characterized resource of M dwarfs for intensive planet and disk searches.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/4b99780da8dbfb95fdaa324138128ae042c3aafa

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Michael C. Liu
2. T. Dupuy
3. B. Bowler
4. E. Gaidos
5. A. Mann
6. K. Allers
7. Kelle Cruz
8. A. Kraus

In Education

1. Michael C. Liu
2. B. Bowler
3. Kelle Cruz
4. K. Allers
5. Andrew A. West
6. K. Covey
7. E. Shkolnik
8. T. Dupuy

In Instrumentation

1. Michael C. Liu
2. T. Dupuy
3. E. Gaidos
4. A. Mann
5. K. Allers
6. B. Bowler
7. Kelle Cruz
8. A. Kraus

Citations in the corpus

• Imaging Extrasolar Giant Planets (2016, background): “…low-mass stars and brown dwarfs in young moving groups has been increasingly uncovered as a result of large all-sky dedicated searches (Figure 4; Shkolnik et al. 2009; Lépine & Simon 2009; Schlieder et al. 2010; Kiss et al. 2010; Rodriguez et al. 2011a; Schlieder et al. 2012a; Schlieder et…”
• BANYAN. II. VERY LOW MASS AND SUBSTELLAR CANDIDATE MEMBERS TO NEARBY, YOUNG KINEMATIC GROUPS WITH PREVIOUSLY KNOWN SIGNS OF YOUTH (2013, background): “Shkolnik et al. (2009) estimated its age to be comprised between 40 and 300 Myr, and then Shkolnik et al. (2009) proposed it as a candidate member to THA.”
• FUNDAMENTAL PARAMETERS AND SPECTRAL ENERGY DISTRIBUTIONS OF YOUNG AND FIELD AGE OBJECTS WITH MASSES SPANNING THE STELLAR TO PLANETARY REGIME (2015, methodology): “…Program (Dupuy & Liu 2012), and the literature (Dahn et al. 2002; Monet et al. 2003; Tinney et al. 2003; Vrba et al. 2004; Ducourant et al. 2008; Shkolnik et al. 2009; Kirkpatrick et al. 2011; Weinberger et al. 2012; Liu et al. 2013; Marocco et al. 2013; Zapatero Osorio et al. 2014) with…”
• HAZMAT. I. THE EVOLUTION OF FAR-UV AND NEAR-UV EMISSION FROM EARLY M STARS (2014, background): “…velocities) to one of these YMGs (e.g., Zuckerman & Song 2004; Torres et al. 2008; Shkolnik et al. 2011, 2012; Kraus et al. 2014), and also exhibits independent youth indicators such as elevated stellar activity levels, low gravity, and possibly lithium absorption (e.g., Shkolnik et al. 2009).”
• THE HAWAII INFRARED PARALLAX PROGRAM. II. YOUNG ULTRACOOL FIELD DWARFS (2016, background): “…et al. (2003a); (73) Reid et al. (2008); (74) Reiners & Basri (2009); (75) Rice et al. (2010b); (76) Salim et al. (2003); (77) Schmidt et al. (2007); (78) Scholz et al. (2005); (79) Shkolnik et al. (2009); (80) Torres et al. (2003); (81) Wahhaj et al. (2011); (82) Zapatero Osorio et al. (2010).”
• PLANETS AROUND LOW-MASS STARS (PALMS). IV. THE OUTER ARCHITECTURE OF M DWARF PLANETARY SYSTEMS (2014, methodology): “For this work we adopt conservative age ranges of 10–300Myr similar to Shkolnik et al. (2009) for the 21 targets without age estimates in the literature.”
• A STELLAR CENSUS OF THE TUCANA–HOROLOGIUM MOVING GROUP (2014, background): “We ultimately trace this paucity of identified candidates to their choice of input samples, which were based on ROSAT or GALEX.”
• CARMENES input catalogue of M dwarfs. I. Low-resolution spectroscopy with CAFOS (2015, background): “…Simon 2008; Jah08: Jahreiß et al. 2008; Law08: Law et al. 2008; LC08: López-Corredoira et al. 2008; Sce08: Scelsi et al. 2008; Cab09: Caballero 2009; Shk09: Shkolnik et al. 2009; Cab10: Caballero et al. 2010; Shk10: Shkolnik et al. 2010; LG11: Lépine & Gaidos 2011; Jan12: Janson et al. 2012;…”
• A CATALOG OF ROTATION AND ACTIVITY IN EARLY-M STARS (2012, background): “Shkolnik et al. (2009) estimate an age of 15− 150 Myrs.”
• A NEAR-INFRARED SPECTROSCOPIC STUDY OF YOUNG FIELD ULTRACOOL DWARFS (2013, result): “Shkolnik et al. (2009) detected strong Li I absorption in the optical spectra of 2M 0557-13 (M7 vl-g) and 2M 0335+23 (M7 vl-g) and determined upper limits to their ages of 10 Myr, consistent with our near-IR classification.”
• BAYESIAN ANALYSIS TO IDENTIFY NEW STAR CANDIDATES IN NEARBY YOUNG STELLAR KINEMATIC GROUPS (2012, background): “…Looper et al. 2010; (cc) Salim & Gould 2003; (dd) Zickgraf et al. 2005; (ee)Shkolnik et al. 2011; (ff) Kiss et al. 2011; (gg) Herbig & Bell1988; (hh) Shkolnik et al. 2009; (ii) da Silva et al. 2009; (jj) Kharchenko et al. 2007; (kk) RAVE; Zwitter et al. 2008; (ll) Gizis et al. 2002; (mm)…”
• A NEARBY M STAR WITH THREE TRANSITING SUPER-EARTHS DISCOVERED BY K2 (2015, background): “Its 6- dimensional UVWXY Z position is inconsistent with the well-known nearby young (≈10–100 Myr) groups summarized by Gagné et al. (2014), as well as other sparser or slightly older groups (Shkolnik et al. 2009; Zuckerman et al. 2013).”