Spectroscopic Distance Estimates Research Articles

A Simple Unified Spectroscopic Indicator of Stellar Luminosity: The Extended Flux-weighted Gravity–Luminosity Relationship

Abstract We show that for a wide range of stellar masses, from 0.3 to 20 M ⊙, and for evolutionary phases from the main sequence to the beginning of the red giant stage, the stellar flux-weighted gravity, g F ≡ g/ , is tightly correlated with absolute bolometric magnitude . Such a correlation is predicted by stellar evolution theory. We confirm this relation observationally, using a sample of 445 stars with precise stellar parameters. It holds over 17 stellar magnitudes from = 9.0 to −8.0 mag with a scatter of 0.17 mag above = −3.0 and 0.29 mag below this value. We then test the relation with 2.2 million stars with 6.5 mag ≥ ≥ 0.5 mag, where “mass-produced” but robust , and from LAMOST DR5 and Gaia DR2 are available. We find that the same relation holds with a scatter of ∼0.2 mag for single stars offering a simple spectroscopic distance estimate good to ∼10%.

Spectroscopic Mass and Host-star Metallicity Measurements for Newly Discovered Microlensing Planet OGLE-2018-BLG-0740Lb

Abstract We report the discovery of the microlensing planet OGLE-2018-BLG-0740Lb. The planet is detected with a very strong signal of Δχ 2 ∼ 4630, but the interpretation of the signal suffers from two types of degeneracies. One type is caused by the previously known close/wide degeneracy, and the other is caused by an ambiguity between two solutions, in which one solution requires the incorporation of finite-source effects, while the other solution is consistent with a point-source interpretation. Although difficult to be firmly resolved based on only the photometric data, the degeneracy is resolved in strong favor of the point-source solution with the additional external information obtained from astrometric and spectroscopic observations. The small astrometric offset between the source and baseline object supports that the blend is the lens and this interpretation is further secured by the consistency of the spectroscopic distance estimate of the blend with the lensing parameters of the point-source solution. The estimated mass of the host is 1.0 ± 0.1 M ⊙ and the mass of the planet is 4.5 ± 0.6 M J (close solution) or 4.8 ± 0.6 M J (wide solution) and the lens is located at a distance of 3.2 ± 0.5 kpc. The bright nature of the lens, with I ∼ 17.1 (V ∼ 18.2), combined with its dominance of the observed flux suggest that radial-velocity (RV) follow-up observations of the lens can be done using high-resolution spectrometers mounted on large telescopes, e.g., Very Large Telescope/ESPRESSO, and this can potentially not only measure the period and eccentricity of the planet but also probe for close-in planets. We estimate that the expected RV amplitude would be .

UPPER LIMITS FROM FIVE YEARS OF BLAZAR OBSERVATIONS WITH THE VERITAS CHERENKOV TELESCOPES

ABSTRACT Between the beginning of its full-scale scientific operations in 2007 and 2012, the VERITAS Cherenkov telescope array observed more than 130 blazars; of these, 26 were detected as very-high-energy (VHE; E > 100 GeV) γ-ray sources. In this work, we present the analysis results of a sample of 114 undetected objects. The observations constitute a total live-time of ∼570 hr. The sample includes several unidentified Fermi-Large Area Telescope (LAT) sources (located at high Galactic latitude) as well as all the sources from the second Fermi-LAT catalog that are contained within the field of view of the VERITAS observations. We have also performed optical spectroscopy measurements in order to estimate the redshift of some of these blazars that do not have spectroscopic distance estimates. We present new optical spectra from the Kast instrument on the Shane telescope at the Lick observatory for 18 blazars included in this work, which allowed for the successful measurement or constraint on the redshift of four of them. For each of the blazars included in our sample, we provide the flux upper limit in the VERITAS energy band. We also study the properties of the significance distributions and we present the result of a stacked analysis of the data set, which shows a 4σ excess.

AUTOMATED IDENTIFICATION OF 2612 LATE-K AND M DWARFS IN THE LAMOST COMMISSIONING DATA USING CLASSIFICATION TEMPLATE FITS

We develop a template-fit method to automatically identify and classify late-type K and M dwarfs in spectra from the LAMOST. A search of the commissioning data, acquired in 2009-2010, yields the identification of 2612 late-K and M dwarfs. The template fit method also provides spectral classification to half a subtype, classifies the stars along the dwarf-subdwarf metallicity sequence, and provides improved metallicity/gravity information on a finer scale. The automated search and classification is performed using a set of cool star templates assembled from the Sloan Digital Sky Survey spectroscopic database. We show that the stars can be efficiently classified despite shortcomings in the LAMOST commissioning data which include bright sky lines in the red. In particular we find that the absolute and relative strengths of the critical TiO and CaH molecular bands around 7000A are cleanly measured, which provides accurate spectral typing from late-K to mid-M, and makes it possible to estimate metallicities in a way that is more efficient and reliable than with the use of spectral indices or spectral-index based parameters such as zeta. Most of the cool dwarfs observed by LAMOST are found to be metal-rich dwarfs. We use a calibration of spectral type to absolute magnitude and estimate spectroscopic distances for all the stars; we also recover proper motions from the SUPERBLINK and PPMXL catalogs. Our analysis of the estimated transverse motions suggests a mean velocity and standard deviation for the UVW components of velocity to be: U=-9.8 km/s; V=-22.8 km/s; W=-7.9 km/s. The resulting values are general agreement with previous reported results, which yields confidence in our spectral classification and spectroscopic distance estimates, and illustrates the potential for using LAMOST spectra of K and M dwarfs for investigating the chemo-kinematics of the local Galactic disk and halo.

2MASS J154043.42−510135.7: a new addition to the 5 pc population

The aim of the project is to find the stars nearest to the Sun and to contribute to the completion of the stellar and substellar census of the solar neighbourhood. We identified a new late-M dwarf within 5 pc, looking for high proper motion sources in the 2MASS-WISE cross-match. We collected astrometric and photometric data available from public large-scale surveys. We complemented this information with low-resolution optical and near-infrared spectroscopy with instrumentation on the ESO NTT to confirm the nature of our candidate. We also present a high-quality medium-resolution VLT/X-shooter spectrum covering the 400 to 2500 nm wavelength range. We classify this new neighbour as an M7.0$\pm$0.5 dwarf using spectral templates from the Sloan Digital Sky Survey and spectral indices. Lithium absorption at 670.8 nm is not detected in the X-shooter spectrum, indicating that the M7 dwarf is older than 600 Myr and more massive than 0.06 M$_{\odot}$. We also derive a trigonometric distance of 4.4 pc, in agreement with the spectroscopic distance estimate, making 2MASS\,J154043.42$-$510135.7 the nearest M7 dwarf to the Sun. This trigonometric distance is somewhat closer than the $\sim$6 pc distance reported by the ALLWISE team, who independently identified this object recently. This discovery represents an increase of 25\% in the number of M7--M8 dwarfs already known at distances closer than 8\,pc from our Sun. We derive a density of $\rho$\,=\,1.9$\pm$0.9$\times$10$^{-3}$\,pc$^{-3}$ for M7 dwarfs in the 8 pc volume, a value similar to those quoted in the literature. This new ultracool dwarf is among the 50 nearest systems to the Sun, demonstrating that our current knowledge of the stellar census within the 5 pc sample remains incomplete. 2M1540 represents a unique opportunity to search for extrasolar planets around ultracool dwarfs due to its proximity and brightness.

WISEA J064750.85-154616.4: a new nearby L/T transition dwarf

Aims: Our aim is to detect and classify previously overlooked brown dwarfs in the solar neighbourhood. Methods: We performed a proper motion search among bright sources observed with the Wide-field Infrared Survey Explorer (WISE) that are also seen in the Two Micron All Sky Survey (2MASS). Our candidates appear according to their red $J$$-$$K_s$ colours as nearby late-L dwarf candidates. Low-resolution near-infrared (NIR) classification spectroscopy in the $HK$ band allowed us to get spectroscopic distance and tangential velocity estimates. Results: We have discovered a new L9.5 dwarf, WISEA J064750.85-154616.4, at a spectroscopic distance of about 14 pc and with a tangential velocity of about 11 km/s, typical of the Galactic thin disc population. We have confirmed another recently found L/T transition object at about 10 pc, WISEA J140533.13+835030.7, which we classified as L8 (NIR).

NEAR-INFRARED METALLICITIES, RADIAL VELOCITIES, AND SPECTRAL TYPES FOR 447 NEARBY M DWARFS

We present metallicities, radial velocities and near-infrared spectral types for 447 M dwarfs determined from moderate resolution (R~2000) near-infrared (NIR) spectra obtained with IRTF/SpeX. These M dwarfs are targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33pc. We present NIR spectral types and new IRTF spectral templates in the Z, J, H and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F, G or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2um as the sole indicator for metallicity. It has an accuracy of 0.12dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for -1.0<[Fe/H]<+0.35dex. We present a new metallicity relation using J-H and J-K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2um. We measured radial velocities by modeling telluric features to determine the absolute wavelength calibration of our spectra, and used M dwarf binaries, observations at different epochs, and comparison to precisely measured radial velocities to demonstrate 4.4km/s accuracy.

A halo blue straggler on a highly eccentric retrograde orbit

Blue straggler, which are stars that appear to be younger than they should be, are an important population of unusual stars in both stellar clusters and the halo field of the Galaxy. Most formation scenarios evoke either stellar collisions or binary stars that transfer mass or merge. We investigate high-velocity stars in the Galactic halo and perform a spectral and kinematical analysis to shed light on their nature and origin. Here we report that SDSSJ130005.62+042201.6 (J1300+0422 for short) is an A-type star of unusually large radial velocity (504.6 $\pm$ 5 \kms). From a quantitative NLTE (and LTE) spectral analysis of medium-resolution optical spectra, the elemental composition is derived. Proper motion measurements combined with a spectroscopic distance estimate allow us to determine its present space velocity. Its kinematical properties are derived by integrating the equation of motion in the Galactic potential. We find J1300+0422 to be metal poor ([M/H]=$-1.2$) and exhibit an $\alpha$-element enrichment ($0.3-0.4$~dex) that is characteristic of the halo population, as confirmed by a kinematical analysis of its 3D space motions, which places it on a highly eccentric retrograde Galactic orbit. The mass of J1300+0422 (1.15 $\pm$ 0.10 M$_\odot$) is higher than the globular cluster turn-off masses indicating that it is a halo blue straggler star. At a Galactic rest-frame velocity of $\approx$467~\kms, the star travels faster than any known blue straggler but is still bound to the Galaxy.

Knowing Our Neighbors: Fundamental Properties of Nearby Stars

The stars within 25 pc constitute the sample that we aspire to know thoroughly. A well-understood, volume-limited sample of nearby stars is an essential input for the stellar luminosity function, the mass-luminosity relationship, the stellar velocity distribution, and the stellar multiplicity fraction, including substellar companions. Such samples help define stellar populations and estimate the amount mass contributed by local stars. In addition, the stars in this volume provide insight into stellar evolution and the history of star formation in the disk. These physical relationships and subsamples describe the makeup of our Galaxy and, by extension, more distant galaxies (Kuiper 1942; Reid & Cruz 2002). However, models are being developed from an incomplete catalog with limited parameters. Although trigonometric parallaxes establish both sample membership and the cosmic distance scale, many objects within reach of ground-based telescopes remain unmeasured. To advance the solar neighborhood census, observations of 56 nearby stars are presented, including astrometric companion search results, along with a possible a new infrared parallax program. Among these nearby stars, Barnard’s star is a fascinating M dwarf, not only because of its nearness and high proper motion, but also because of van de Kamp’s (1963) announcement that it had a planet. However, PDS scans and analyses of 900 Leander McCormick Observatory photographic plates failed to detect any planets. This time-series analysis using Lomb-Scargle periodograms (Press et al. 1996) would have detected planets with 2.2 Jupiter masses (MJ) or greater. Prior to the timeseries analysis, the relative parallax, proper motion, and secular acceleration of Barnard’s star were measured to be 546 1 mas, 10.3612 0.0002 yr 1 in 355.905 0.001 , and 1.25 0.04 mas yr , respectively. The available photometry and spectroscopy of the 12 reference stars used indicate a correction to absolute of 6 7 mas would be necessary, resulting in an absolute parallax of 552 7 mas, corresponding to a distance of 1.81 0.02 pc and a transverse velocity of 89 km s . These results are comparable to those obtained with more modern equipment. An additional search for potential nearby planets was undertaken through similar time-series analyses of stars in the University of Virginia Southern Parallax Program (SPP; Ianna 1993). For 12 stars (LHS 34, 271, 337, 532, 1134, 1565, 2310, 2739, 2813, 3064, 3242, and 3418), no indication of any unseen companions was detected. However, LHS 288 shows trends suggestive of a 2.4MJ planet in a 7 yr orbit. These high proper motion stars all lie within the solar neighborhood. With the exception of the white dwarf LHS 34, these stars are M dwarfs. After a minimum of 50 observations spread over at least 3 years, the relative parallax solutions have errors of less than 3 mas. An upper limit to the mass of companions remaining undetected was established for each star individually; for longperiod orbits, these range from 1.7MJ to 18MJ. The lack of any clear signal due to a companion may suggest that gas giants are less common around M dwarfs than solar-type stars. Before astrometric companions are investigated, trigonometric parallaxes are obtained that can establish membership in the solar neighborhood. A subsample of 43 potential nearby stars was included in the Cerro Tololo Inter-American Observatory Parallax Investigation (CTIOPI), based on less accurate photometric and spectroscopic distance estimates. Astrometric, photometric, and spectroscopic observations began in 2003 December. Although at least another year of observations is anticipated to finalize these measurements, preliminary results based on observations through mid-2006 are available. According to preliminary parallaxes from this CTIOPI subsample, 28 of the stars are probable members of the solar neighborhood, including three stars (LP 991-84, LHS 6167, and LP 876-10) that apparently lie within 10 pc. Three more stars lie near the 25 pc boundary, and their final parallaxes may still qualify them as members. In addition, LP 869-26 is an apparent binary with newly resolved components separated by approximately 0.7 0.3 . The nearest stars tend to display large proper motions. As expected, high proper motion stars predominate in this subsample. Preliminary proper motions indicate that nine stars have proper motions greater than 0.5 yr , with 2MASS 02511490 0352459 and 23062928 0502285 moving more than 1.0 yr . For this subsample, the proper motions convert to tangential velocities that range from about 10 to 129 km s . Previously unidentified members of the solar neighborhood are anticipated to be so cool, red, and dim that they were missed in previous studies. Preliminary photometry (VC, RC, and IC) is available for 16 stars in this CTIOPI subsample. These stars range from approximately 10th to 20th magnitude in VC. In

LSR 0602+3910: Discovery of a Bright Nearby L-Type Brown Dwarf

We report the discovery of LSR 0602+3910, an L dwarf of class L1. The object was initially identified by Lepine et al. as a new high proper motion star lying close to the Galactic plane. Its Two Micron All Sky Survey value of J-Ks = 1.43 is consistent with an L dwarf, which we now confirm spectroscopically. In addition, we see a signature of Li I absorption, making LSR 0602+3910 a brown dwarf, one of the brightest known (Ks = 10.86). Among L dwarfs, it is second in brightness to the combined light of 2MASS 0746+20, a close binary system. We see no indication that LSR 0602+3910 is a binary, although high-resolution imaging will be required to confirm this. Spectroscopic and photometric distance estimates agree very well, placing LSR 0602+3910 at d = 10.6 ± 0.8 pc. LSR 0602+3910 was most likely missed in previous searches because of its proximity to the plane, the region that most searches avoided. We estimate that some 40% of bright L dwarfs are missed because of this selection effect.

Search for nearby stars among proper motion stars selected by optical-to-infrared photometry

We have identified two late M dwarfs within 10 parsecs of the Sun, by cross-correlating the Luyten NLTT catalogue of stars with proper motions larger than 0.18 arcsec/yr, with objects lacking optical identification in the 2MASS data base. The 2MASS photometry was then combined with improved optical photometry obtained from the SuperCOSMOS Sky Surveys. The two objects (LP775-31 and LP655-48) have extremely red optical-to-infrared colours ((R-K)~7) and very bright infrared magnitudes (K_s<10): follow-up optical spectroscopy with the ESO 3.6-m telescope gave spectral types of M8.0 and M7.5 dwarfs, respectively. Comparison of their near-infrared magnitudes with the absolute magnitudes of known M8 and M7.5 dwarfs with measured trigonometric parallaxes yields spectroscopic distance estimates of 6.4+/-1.4 parsecs and 8.0+/-1.6 parsecs for LP775-31 and LP655-48, respectively. In contrast, Cruz & Reid (2002) recently determined spectral types of M6 for both objects, and commensurately larger distances of 11.3+/-1.3 parsecs and 15.3+/-2.6 parsecs. LP655-48 is also a bright X-ray source (1RXS J044022.8-053020). With only a few late M dwarfs previously known within 10 parsecs, these two objects represent an important addition to the census of the Solar neighbourhood.

New nearby stars among bright APM high proper motion stars

As part of a new southern sky survey for faint high proper motion stars based on Automatic Plate Measuring (APM) measurements of UK Schmidt Telescope plates, we have found a large number of previously unknown brighter objects. Spectroscopic follow-up observations with the European Southern Observatory New Technology Telescope of 15 of these new, relatively bright (12 0.45 arcsec yr - 1 ) show one-third of them to be nearby (d < 25 pc). Among the nearby stars is an M6 dwarf with strong emission lines at a spectroscopic distance of about 11 pc and an M4 dwarf at about 13 pc. Coupled with earlier South African Astronomical Observatory spectroscopic observations of three similar bright high proper motion stars, the success rate of finding nearby stars (d < 25 pc) is about 45 per cent. All newly discovered nearby stars have disc kinematics confirmed by radial velocity measurements from our spectra. In addition there are several high-velocity stars with halo kinematics in the sample, mainly subdwarfs, at about 60 to 110 pc distance. These high-velocity stars are interesting targets for further study of the Galactic escape velocity. One of the detected nearby high proper motion stars was formerly thought to be an M giant in the Small Magellanic Cloud. The spectrum of one M3 star shows a strong blue continuum, which is likely to signify the presence of a hot companion. Spectroscopic follow-up observations of high proper motion stars are shown to be an effective tool in the search for the missing stars in the Solar neighbourhood. Candidates for more extensive trigonometric parallax determination can be selected on the basis of the spectroscopic distance estimates.

Search for nearby stars among proper motion stars selected by optical-to-infrared photometry

We present the discovery of a previously unknown very nearby star - LHS 2090 at a distance of only d=6 pc. In order to find nearby (i.e. d < 25 pc) red dwarfs, we re-identified high proper motion stars ($\mu >$ 0.18 arcsec/yr) from the NLTT catalogue (Luyten \cite{luyten7980}) in optical Digitized Sky Survey data for two different epochs and in the 2MASS data base. Only proper motion stars with large $R-K_s$ colour index and with relatively bright infrared magnitudes ($K_s<10$) were selected for follow-up spectroscopy. The low-resolution spectrum of LHS 2090 and its large proper motion (0.79 arcsec/yr) classify this star as an M6.5 dwarf. The resulting spectroscopic distance estimate from comparing the infrared $JHK_s$ magnitudes of LHS 2090 with absolute magnitudes of M6.5 dwarfs is $6.0\pm1.1$ pc assuming an uncertainty in absolute magnitude of $\pm$0.4 mag.

Distances to the High Galactic Latitude Molecular Clouds G192−67 and MBM 23–24

We report on distance determinations for two high Galactic latitude cloud complexes, G192-67 and MBM 23-24. No distance determination exists in the literature for either cloud. Thirty-four early type stars were observed towards the two clouds, more than half of which have parallaxes measured by the Hipparcos satellite. For the remaining stars we have made spectroscopic distance estimates. The data consist of high resolution echelle spectra centered on the Na I D lines, and were obtained over six nights at the Coude Feed telescope at Kitt Peak National Observatory. Interstellar absorption lines were detected towards some of the stars, enabling estimates of the distances to the clouds of 109 +/- 14 pc for G192-67, and of 139 +/- 33 pc for MBM 23-24. We discuss the relationship of these clouds to other ISM features such as the Local Hot Bubble and the local cavity in neutral hydrogen.

Echelle spectroscopy of CD -41 deg 13967 - The young central star of a new planetary nebula

view Abstract Citations (12) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Echelle Spectroscopy of CD -41 degrees 13967: The Young Central Star of a New Planetary Nebula McCarthy, James K. ; Rich, R. Michael ; Becker, S. R. ; Butler, K. ; Husfeld, D. ; Groth, H. G. Abstract High-resolution CCD spectra obtained with the Palomar 60 inch (1.5 m) echelle spectrograph and subsequently confirmed and extended using the CTIO 4 m echelle spectrograph have revealed that the hot star CD -41° 13967 is the young central star of a previously unknown low-excitation planetary nebula. Presented in this paper is a detailed analysis of our CCD echelle spectra of CD -41° 13967, which are well fitted by non-LTE model atmosphere line profiles corresponding to Teff = 27,000 K, log (g) = 3.1, and a He abundance 3 times solar. These best-fit model parameters imply a mass of 0.63 Msun and a post-asymptotic giant branch (AGB) age of 1250 yr for the central star, based on a comparison with central star of planetary nebula (CSPN) evolutionary tracks in the distance-independent Teff-log (g) plane. Using recent UBVRI CCD photometry corrected for extinction along with the Eddington flux emerging from the best-fit non-LTE model atmosphere, we derive a spectroscopic distance estimate of 3.5 kpc to CD - 41° 13967. This together with the Galactic coordinates (lII = 359.0; bII = - 33.5) strongly suggests that CD -41° 13967 belongs to the Galactic halo population, a suggestion supported by the results of our stellar abundance analyses for silicon, [Si/H] = -0.20±0.10 and oxygen, [O/H] = -0.43±0.20 as well as by the mean of our stellar radial velocity measurements <Vr>* = -91±2 km s-1; compare also with our result, <Vr>PN = -97±2 km s-1). The surrounding planetary nebula, He 3-1863, shows an angular extent greater than 6" (FWHM) on the E/W slit of our CTIO spectrograms. The excitation class of the nebula is zero, with only Hα, Hβ, Hγ, Hδ, [N II] 5755, 6548, 6584 Å, [O I] 6300, 6364 Å, [O II] 7320, 7330 Å, and [S II] 6717, 6731 Å lines in evidence; lacking is any [O III] 4363, 4959, 5007 Å emission. This is consistent with the low Teff; determined for the central star. Subsequent narrow-band Hα CCD imaging reveals that He 3-1863 is a centrally concentrated elliptical nebula with a total E/W extent ≥17" and N/S extent ≥ 13" on the sky. Publication: The Astrophysical Journal Pub Date: April 1991 DOI: 10.1086/169898 Bibcode: 1991ApJ...371..380M Keywords: Early Stars; Echelle Gratings; Nonequilibrium Thermodynamics; Planetary Nebulae; Stellar Spectra; Charge Coupled Devices; Hot Stars; Stellar Atmospheres; nebulae: planetary; stars: abundances; stars: early-type; stars: individual (CD -41° 13967); Astrophysics full text sources ADS | data products SIMBAD (1)

A quest for the red companion in six cataclysmic binaries

view Abstract Citations (85) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A quest for the red companion in six cataclysmic binaries. Young, P. ; Schneider, D. P. Abstract Near-infrared CCD spectra of six cataclysmic binaries have been obtained in an attempt to detect their red dwarf components. Similar observations of M dwarfs yield a classification scheme, based on TiO bands, which can be used to describe the red dwarfs in cataclysmic binaries. Observations of AM Her while in its low state revealed a red dwarf of type M4(+) V and a distance of 80 pc. The red dwarf in DQ Her was detected in an observation centered on mid-eclipse. The red star in DQ Her has a spectral type of M3(+) V, a mass = 0.32 solar mass, and a radius = 0.45 solar radius. The red star in DQ Her does not lie on the main sequence; although its temperature is correct for its mass, the radius is 25% too large. A spectroscopic distance estimate of 400 pc to the DQ Her binary system was obtained; in four additional systems, the red dwarf defied detection. Lower limits to their distances are given. Publication: The Astrophysical Journal Pub Date: August 1981 DOI: 10.1086/159105 Bibcode: 1981ApJ...247..960Y Keywords: Companion Stars; Dwarf Stars; Infrared Spectra; Novae; Stellar Spectrophotometry; Charge Coupled Devices; Near Infrared Radiation; Stellar Magnitude; Stellar Mass Accretion; Titanium Oxides; Astronomy full text sources ADS | data products SIMBAD (13)