Runaway M Dwarf Candidates From the Sloan Digital Sky Survey

Favia, Andrej; West, Andrew A.; Theissen, Christopher A.

doi:10.1088/0004-637x/813/1/26

Cited by 12 publications

(11 citation statements)

References 74 publications

(148 reference statements)

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“…However, in Favia et al (2015) CA297 (= SDSS J140921.10+370542.6) is listed as a runaway M dwarf candidate. Its SDSS spectrum is of higher S/N than our CAFOS spectrum and clearly rules out a WD.…”

Section: Other Spectroscopically Rejected (Candidate) Wdsmentioning

confidence: 99%

Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars

Scholz

Meusinger

Schwope

et al. 2018

A&A

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Aims. With our low-resolution spectroscopic observing program for selected blue proper motion stars, we tried to find new white dwarfs (WDs) in the solar neighbourhood. Methods. We used the Lépine & Shara Proper Motion (LSPM) catalogue with a lower proper motion limit of 150 mas/yr and the Second US Naval Observatory CCD Astrograph Catalog (UCAC2) for proper motions down to about 90 mas/yr. The LSPM and UCAC2 photometry was combined with Two Micron All Sky Survey (2MASS) near-infrared (NIR) photometry. Targets selected according to their blue optical-to-NIR and NIR colours were observed mainly at Calar Alto. The spectra were classified by comparison with a large number of already known comparison objects, including WDs, simultaneously observed within our program. Gaia DR2 parallaxes and colours were used to confirm or reject spectroscopic WD candidates and to derive improved effective temperatures. Results. We found ten new WDs at distances between 24.4 pc and 79.8 pc, including six hot DA WDs: GD 221 (DA2.0), HD 166435 B (DA2.2), GD 277 (DA2.2), 2MASS J19293865+1117523 (DA2.4), 2MASS J05280449+4105253 (DA3.6), and 2MASS J05005185-0930549 (DA4.2). The latter is rather bright (G ≈ 12.6) and with its Gaia DR2 parallax of ≈ 14 mas it appears overluminous by about 3 mag compared to the WD sequence in the Gaia DR2 colour-magnitude diagram. It may be the closest extremely low mass (ELM) WD to the Sun. We further classified 2MASS J07035743+2534184 as DB4.1. With its distance of 25.6 pc it is the second nearest known representative of its class. With GD 28 (DA6.1), LP 740-47 (DA7.5), and LSPM J1919+4527 (DC10.3) three additional cool WDs were found. Gaia DR2 parallaxes showed us that four of our candidates but also two previously supposed WDs (WD 1004+665 and LSPM J1445+2527) are in fact distant Galactic halo stars with high tangential velocities. Among our rejected WD candidates, we identified a bright (G = 13.4 mag) G-type carbon dwarf, LSPM J0937+2803, at a distance of 272 pc.

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Section: Other Spectroscopically Rejected (Candidate) Wdsmentioning

confidence: 99%

Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars

Scholz

Meusinger

Schwope

et al. 2018

A&A

View full text Add to dashboard Cite

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“…Subsequent surveys have discovered dozens of further candidates. The recent review paper of Brown (2015) gives a summary, while there are subsequent papers by Savcheva et al (2014), Theissen & West (2014), Favia et al (2015), Hawkins et al (2015), Kunder et al (2015), Li et al (2015), and Vickers et al (2015). It was noticed early on that the candidate HVSs exhibited significant spatial anisotropy on the sky with 8 out of the 14 HVSs at that time being located in two constellations despite a fifth of the sky having been surveyed (Brown et al 2009b).…”

Section: Introductionmentioning

confidence: 99%

A Dipole on the Sky: Predictions for Hypervelocity Stars From the Large Magellanic Cloud

Boubert

Evans

2016

ApJL

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We predict the distribution of hypervelocity stars (HVSs) ejected from the Large Magellanic Cloud (LMC), under the assumption that the dwarf galaxy hosts a central massive black hole (MBH). For the majority of stars ejected from the LMC, the orbital velocity of the LMC has contributed a significant fraction of their galactic rest-frame velocity, leading to a dipole density distribution on the sky. We quantify the dipole using spherical harmonic analysis and contrast with the monopole expected for HVSs ejected from the Galactic center (GC). There is a tendril in the density distribution that leads the LMC, which is coincident with the well-known and unexplained clustering of HVSs in the constellations of Leo and Sextans. Our model is falsifiable since it predicts that Gaia will reveal a large density of HVSs in the southern hemisphere.

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“…Finally, two subdwarfs in our sample with SDSS spectra (ID = 8 and 29) appear to have very high Galactic motions with velocities slightly above ∼450 km s −1 , which is the accepted escape velocity threshold in the halo (Favia et al 2015;Kenyon et al 2008). Whether these stars are runaway candidates is to be confirmed.…”

Section: Space Motionsmentioning

confidence: 66%

New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools

Lodieu

Contreras

Osorio

et al. 2017

A&A

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Aims. We aim at developing an efficient method to search for late-type subdwarfs (metal-depleted dwarfs with spectral types ≥ M5) to improve the current statistics. Our objectives are: improve our knowledge of metal-poor low-mass dwarfs, bridge the gap between the late-M and L types, determine their surface density, and understand the impact of metallicity on the stellar and substellar mass function. Methods. We carried out a search cross-matching the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) and the Two Micron All Sky Survey (2MASS), and different releases of SDSS and the United Kingdom InfraRed Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) using STILTS, Aladin, and Topcat developed as part of the Virtual Observatory tools. We considered different photometric and proper motion criteria for our selection. We identified 29 and 71 late-type subdwarf candidates in each crosscorrelation over 8826 and 3679 square degrees, respectively (2312 square degrees overlap). We obtained our own low-resolution optical spectra for 71 of our candidates. : 26 were observed with the Gran Telescopio de Canarias (GTC; R ∼ 350, λλ5000-10000 Å), six with the Nordic Optical Telescope (NOT; R ∼ 450, λλ5000-10700 Å), and 39 with the Very Large Telescope (VLT; R ∼ 350, λλ6000-11000 Å). We also retrieved spectra for 30 of our candidates from the SDSS spectroscopic database (R ∼ 2000 and λλ 3800-9400 Å), nine of these 30 candidates with an independent spectrum in our follow-up. We classified 92 candidates based on 101 optical spectra using two methods: spectral indices and comparison with templates of known subdwarfs. Results. We developed an efficient photometric and proper motion search methodology to identify metal-poor M dwarfs. We confirmed 86% and 94% of the candidates as late-type subdwarfs from the SDSS vs 2MASS and SDSS vs UKIDSS cross-matches, respectively. These subdwarfs have spectral types ranging between M5 and L0.5 and SDSS magnitudes in the r = 19.4-23.3 mag range. Our new late-type M discoveries include 49 subdwarfs, 25 extreme subdwarfs, six ultrasubdwarfs, one subdwarf/extreme subdwarf, and two dwarfs/subdwarfs. In addition, we discovered three early-L subdwarfs to add to the current compendium of L-type subdwarfs known to date. We doubled the numbers of cool subdwarfs (11 new from SDSS vs 2MASS and 50 new from SDSS vs UKIDSS). We derived a surface density of late-type subdwarfs of 0.040 +0.012 −0.007 per square degree in the SDSS DR7 vs UKIDSS LAS DR10 cross-match (J = 15.9-18.8 mag) after correcting for incompleteness. The density of M dwarfs decreases with decreasing metallicity. We also checked the Wide Field Survey Explorer (AllWISE) photometry of known and new subdwarfs and found that midinfrared colours of M subdwarfs do not appear to differ from their solar-metallicity counterparts of similar spectral types. However, the near-to-mid-infrared colours J − W2 and J − W1 are bluer for lower metallicity dwarfs, results that may be used as a criterion to look for late-type subdwarfs in future sea...

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Runaway M Dwarf Candidates From the Sloan Digital Sky Survey

Cited by 12 publications

References 74 publications

Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars

Spectroscopic classification and Gaia DR2 parallaxes of new nearby white dwarfs among selected blue proper motion stars

A Dipole on the Sky: Predictions for Hypervelocity Stars From the Large Magellanic Cloud

New ultracool subdwarfs identified in large-scale surveys using Virtual Observatory tools

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